In the human body, protein is a building material. Molecules of this substance are present in hair, bones, nails, muscles. They are also found in organs (lungs, pancreas, liver, kidneys, etc.). Protein is involved in chemical processes that are of great importance for human life. Therefore, when the blood passes through the kidneys, unnecessary elements are excreted from the body with urine, useful elements remain, including protein. But if it gets into the urine, then you should be examined by specialist doctors, make a detailed analysis, and establish the cause of this problem.
Do not worry if the content of the molecules of the substance is less than 0.03 g / l. Reasons for having physiological protein In urine tests, the following factors may be:- An increase in temperature with ARVI;
- Stress;
- Overheating or cooling;
- The use of certain medications;
- Unbalanced diet, i.e. increased intake of protein-containing foods;
- Great physical overload.
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The imaginary protein is determined when the analysis is incorrectly collected. It is necessary to observe hygiene, to prevent vaginal, menstrual secretions from entering the urine. If proteinuria is found in pregnant women in the urine, then this may be a consequence of toxicosis (in the first or second trimester). On last month in some women in position, the amount of grams of protein per liter of sputum reaches 12%. This happens with a placental disorder. After childbirth, the symptoms disappear. As a result of diseases of the nervous system, acidosis, heavy sweating, delayed milk release in young mothers, a functional protein may be present in the urine. After the above symptoms pass, the tests return to normal. In adolescents who suffer from anemia, eat irregularly, get tired quickly - orthostatic protein is observed. Again, when the causes are eliminated, proteinuria goes away. In summer, spring, some people have an exacerbated allergy, the presence of molecules of this substance in urine is a consequence of the disease. An increased protein content in sputum sometimes warns of the presence of serious diseases:- Malignant neoplasms (cancer) of the kidneys;
- Mechanical damage to the kidneys;
- Diabetes;
- Leukemia, osteosarcoma;
- Glomerulonephritis, nephritis;
- Heart failure.
From what I read, it turned out that the protein in the urine is a warning that there are some inflammatory processes in the human body. There is no cure for proteinuria itself. The root cause should be established, due to which the patient's analysis is not normal. This will require the help of doctors, repeated delivery of all samples, diagnosis and timely treatment.
Protein in the urine (proteinuria, albuminuria) is the presence of a protein detected in the urine test, which should not be in the urine of a healthy person. The presence of protein can be a sign of certain diseases of the body or a consequence of increased stress and poor nutrition, therefore, in order to make a correct diagnosis, it is necessary to take into account the amount of protein detected and the accompanying symptoms.
General information
Protein is a high molecular weight organic substance that serves as a building material for various tissues. Since the presence of protein in urine is a sign of disturbances in the functioning of the body, when passing a general urine test, biochemical studies are carried out to determine the concentration of the protein (in the analysis form it is abbreviated "PRO").
Although normally there should be no protein in urine at all, a protein concentration of up to 0.033 g is considered normal. per litre. This definition of the norm is related to the accuracy laboratory methods, which do not detect protein concentrations below the indicated figures.
When protein is detected in the urine of a healthy person, 70% is uromucoid (a product of kidney tissue).
Proteinuria can be:
- mild, in which the protein concentration does not exceed 0.5 g/l;
- moderate (concentration does not exceed 2 g/l);
- expressed (protein concentration above 2 g/l).
A mild degree of proteinuria is often eliminated on its own, and with a moderate and severe degree, the highest quality diagnostics and a rather long complex treatment are required.
Types of proteinuria
Depending on the factors that cause the appearance of protein in the urine, proteinuria can be:
- Physiological (transient). It occurs in newborns, as well as in healthy people when exposed to provoking factors (increased stress, etc.).
- Pathological. It develops with kidney diseases and some extrarenal pathologies.
- False. It occurs when the biomaterial is not collected correctly for analysis, when the protein enters the urine already in the urinary canal, or when certain antibacterial drugs and radiopaque substances are used.
Focusing on the place of occurrence of the pathology, proteinuria is isolated:
- Prerenal, which is associated with a pronounced breakdown of red blood cells and tissue protein breakdown. Protein molecules with a pathologically low molecular weight resulting from the breakdown can pass through an intact glomerular (kidney) filter into the urine.
- Renal, which occurs with kidney pathology (may be glomerular and tubular).
- Postrenal, which is associated with a lesion urinary tract.
The rate of protein in the urine
The specificity and sensitivity of conventional qualitative and quantitative methods for detecting protein in the urine is not very high, so in the past proteinuria was diagnosed simply by detecting protein in the urine.
After the introduction of more sensitive methods, proteinuria is diagnosed when the level of protein in the urine exceeds the norm (normal includes physiological proteinuria).
At the initial stage of a biochemical study of urine, a qualitative analysis is carried out, which allows you to detect the presence of a protein, but does not determine its concentration.
If a qualitative analysis showed the presence of a protein, the following is performed:
- quantitative analysis using turbidimetric or colorimetric methods;
- semi-quantitative analysis using diagnostic test strips or the Brandberg-Roberts-Stolnikov method.
The most accurate are colorimetric methods.
The features of the methods used, which cover a different range of uroproteins, affect the concept of the norm - if the analysis was carried out using 3% sulfosalicylic acid, the protein norm is up to 0.03 g / l, and when using the pyrogallol method, the limit of the norm is 0.1 g / l .
Due to the fact that laboratories can use different methods, the norm must be indicated in the analysis form.
If a protein is detected in small amounts (usually indicated in the analysis form as traces of protein), it is recommended to retake the analysis.
If the result of the analysis is in doubt, a daily urine test is prescribed.
Since normally the protein filtered through the renal "filters" is contained in daily urine in small quantities, the concentration is from 20 to 50 mg per day for an adult (some authors indicate 100-150 mg and even 150-200 mg).
In the first month of life, the concentration of protein in the urine in the absence of pathology can exceed the indicated values by 4 times.
In the urine of a healthy person, proteins can appear only at their high concentration in the blood and at a protein molecular weight of no more than 100–200 kDa.
Causes of protein in the urine
Normally, protein in the urine of absolutely healthy people should be absent. Permissible concentration is considered to be up to 0.033 gr. per litre. Exceeding the norm in both adults and children means the presence of physiological or pathological problems that require identification and correction or treatment.
Protein in the urine of healthy people
Protein in the urine of healthy people can appear in small concentrations when:
- Physical stress, which is caused by intense physical activity, intense training and long walking (tension proteinuria, work or marching). Protein in the urine is due to stress secretion of adrenaline and norepinephrine, which cause a temporary disruption of glomerular blood flow. Protein is detected in the first portion of urine after loading.
- Taking a cold shower or bath.
- Overheating (albuminuria solaris). It is provoked by a pronounced reaction of the skin to insolation, it can occur when the skin is irritated with iodine and other aggressive substances.
- Increased blood levels of adrenaline and norepinephrine. It is observed in hypertensive crises, pheochromocytoma and psycho-emotional stress.
- Concussion and epilepsy (centrogenic proteinuria).
- The predominance in the diet of foods that are rich in protein (alimentary proteinuria). These products include meat (especially fatty varieties), protein-carbohydrate mixtures and other sports nutrition.
- Violation of renal hemodynamics, which occurs with a long stay in a vertical position (orthostatic or postural proteinuria). It is detected in 12 - 40% of children and adolescents. Protein in the urine in a horizontal position can quickly disappear with a transient variant of orthostatic proteinuria or decrease with a persistent variant. Violation of renal hemodynamics occurs with lordosis and compression of the inferior vena cava in a standing position, or with the release of renin as a result of a change in the volume of circulating plasma.
- Prolonged and vigorous palpation in the region of the kidneys (palpatory proteinuria).
- Dehydration and profuse sweating.
- Acute fever. It is more common in children and the elderly. With a febrile type of proteinuria, the protein should return to normal after the temperature normalizes.
- Heart failure (congestive proteinuria).
Protein in the urine is also increased in newborns in the first month of life, in physically poorly developed children over 7 years old and in adolescence against the background of hormonal changes and intensive growth of the body.
With the elimination of provoking factors, urinalysis returns to normal.
Traces of protein (negligible concentration) can also be detected after infectious diseases or in the breakdown of protein in tissues due to burns, frostbite and hemolytic disease.
With physiological proteinuria, the protein concentration usually does not exceed 1.0 g / day.
Protein in the urine as a sign of pathology
Increased protein in the urine is detected in renal pathologies and extrarenal diseases.
Renal proteinuria
Elevated protein in the urine is a constant symptom of kidney disease.
Renal proteinuria can be:
- Glomerular (glomerular). It develops when the glomerular filter is damaged, accompanies glomerulonephritis and nephropathy associated with vascular or metabolic diseases, amyloidosis, gout, diabetic glomerulosclerosis, renal vein thrombosis, congestive kidney, hypertension, nephrosclerosis. With this type of pathology, plasma proteins in large quantities penetrate from the blood into the urine. Damage to the glomerular filter is observed with the deposition of fibrin, immune complexes and cellular infiltration, with changes in glomerular blood flow, or with a lack of specific glycoproteins and proteoglycans.
- Tubular (canalicular). It is characteristic of acute and chronic pyelonephritis, heavy metal poisoning, acute tubular necrosis, interstitial nephritis, chronic renal transplant rejection, genetic tubulopathies, and potassium penic nephropathy. Occurs when the tubules are unable to absorb proteins that have passed through the unchanged glomerular filter, or when the protein is released by the epithelium of the tubules.
May be observed mixed type pathology that is characteristic of renal failure.
Extrarenal proteinuria
Protein in the urine can occur in the absence of pathology in the kidneys. Extrarenal proteinuria May be:
- Prerenal. This form of pathology is characteristic of multiple myeloma, severe hemolysis (destruction of red blood cells), myopathy and monocytic leukemia, hemolytic anemia and crush syndrome. May occur with electric shock, with heart disease in the stage of decompensation, with ascites abdominal cavity, craniocerebral injuries, hemorrhages, vegetative crises, manic states, an attack of cholelithiasis and severe myocardial infarction.
- Postrenal. It is observed in urolithiasis, kidney tuberculosis, tumors in the kidney or urinary tract, cystitis, pyelitis, prostatitis, urethritis and vulvovaginitis.
Protein in the urine can also be detected in allergic reactions.
Protein in the urine of pregnant women
Protein in the urine of pregnant women can be a variant of the norm and a sign of pathology.
The physiological increase in the concentration of protein in the urine is associated with an increase in the uterus and compression of the veins of the small pelvis.
Normally, in women in the first trimester, the concentration of protein in the urine does not exceed 0.03 g / l (corresponds to the general norm), but the growing uterus gradually increases pressure on the veins of the small pelvis, therefore, in the second and third trimester, protein compounds in greater quantities penetrate through the renal urine filter.
The concentration of protein in the urine of pregnant women in the second trimester can be 0.04 g / l, and in the third trimester - 0.05 g / l.
An increase in protein concentration above the indicated figures can be observed with:
- gestose;
- dehydration;
- metabolic disorders;
- inflammation of the glomeruli of the kidneys;
- increase in the secretion of the genital organs;
- pyelonephritis and cystitis.
Since the indicators in the analyzes in pregnant women can change several times a day, one general urine test cannot be the basis for diagnosing pathology.
Protein in the urine of a child
In children, normal protein in the urine is not detected or is present in small quantities. The limit of the norm is the concentration of 0.036 g / l. In newborns of the first month of life, a fourfold increase in protein concentration is also considered the norm.
Increased protein in the urine in a child can be observed with:
- overfeeding the baby, as the load on the body increases;
- allergic reaction in the acute stage;
- infectious diseases, and protein in the urine can be detected even 2 weeks after recovery;
- rise in temperature;
- hypothermia of the body;
- severe stress that the child has recently suffered;
- poisoning or drug intoxication;
- diseases of the kidneys or urinary tract;
- problems with the processes of hematopoiesis.
Often, an increase in protein in a urine test in a child is associated with improper collection of urine - a special plastic jar is used to collect the analysis, but in young children, urine is often collected in a non-sterile pot, and as a result, traces of protein are detected in the analysis. Before collecting the analysis from the girl, it is recommended for the time of emptying Bladder cover the entrance to the vagina with a cotton swab so that extraneous secretions do not enter the urine.
Symptoms
In most cases, a small amount of protein in the urine and a mild degree of proteinuria are not accompanied by obvious symptoms.
Long-term elevated protein in the urine may be accompanied by:
- bone pain that occurs with large losses of protein (with multiple myeloma, etc.);
- deposition of protein molecules in the fingers of the extremities and their swelling;
- drowsiness and dizziness as a result of an increase in the concentration of calcium in the blood;
- discoloration of urine due to the presence of red blood cells;
- fever and chills with inflammation, as well as other symptoms of the underlying disease.
Which doctor to contact
A urinalysis is usually ordered by a general practitioner or pediatrician. If a significant concentration of protein in the urine is detected, the patient is referred to or to rule out kidney disease.
If necessary, additional tests and examinations are prescribed.
Treatment
An increased concentration of protein in the urine is caused by a number of factors, so treatment is prescribed by a doctor after a thorough diagnosis of the patient.
With proteinuria, which is expressed in a weak form, medications do not apply. Patients are advised:
- normalize the daily routine;
- pick up proper diet nutrition;
- to refuse from bad habits;
- reduce physical activity;
- observe the drinking regime.
With moderate and severe proteinuria and the manifestation of nephrotic syndromes, hospitalization, bed rest and a special diet with a maximum restriction of salt and fluid are indicated.
Depending on the cause of proteinuria, apply:
- immunosuppressants;
- antibacterial drugs;
- corticosteroids;
- ACE inhibitors;
- antihypertensive drugs, etc.
Also, according to indications, blood is purified by hemosorption or plasmapheresis.
To eliminate the increased protein in the urine, it is necessary to treat the disease that caused proteinuria.
A protein appeared in the urine - this is a serious signal that cannot be ignored, since a healthy person should not have this.
The presence of protein in the urine experts call proteinuria, which can be detected using a simple method - a urinalysis.
Considering the importance of such a symptom for the diagnosis of many diseases internal organs, we propose to figure out why protein appears in the urine, which specialist you need to contact and why such a sign is dangerous.
As we have already said, the appearance of protein in the urine is commonly called proteinuria.
Most often, proteinuria indicates a violation of the kidneys, which pass an excessive amount of proteins into the urine.
Proteinuria is usually divided into pathological and physiological. Pathological proteinuria develops against the background of various diseases. Physiological proteinuria can occur in a completely healthy person. We will talk in more detail about the causes of pathological and physiological proteinuria later.
Causes of physiological proteinuria may be the following factors:
After elimination of the causative factor of physiological proteinuria, the indicators in the analysis of urine correspond to the norm. But in the case when the factor that caused the appearance of protein in the urine is not eliminated in a timely manner, the development of pathological proteinuria is possible.
Protein in the urine in men most often appears with inflammation of the prostate gland or urethra. In this case, you need to consult a urologist.
As you can see, there are a lot of reasons why protein appears in the urine. And since proteinuria is just a symptom of a disease, treatment will be selected individually for each patient.
Therefore, having received a urine test in which the protein norm exceeds the permissible value, it is necessary to seek advice from a nephrologist. We categorically do not recommend self-medication, since treatment with folk remedies is not always effective, and sometimes dangerous to health.
Protein in urine: normal
The level of protein in the urine in women should not normally exceed 0.1 g/l, the only exception is the level of protein in the urine during pregnancy, the norm of which in the early lines is up to 0.3 g/l, and in the later lines - up to 0.5 g/l.
Protein in urine in men should normally not be higher than 0.3 g / l. This figure is slightly higher than that of women, since the male sex is more likely to be subjected to excessive physical exertion than the female.
In a child, the level of protein in the urine is considered normal - 0.033 g / l.
The daily loss of protein in the urine ranges from 50 to 140 mg.
Proper preparation for the delivery of a general urine test helps to avoid erroneous research results. Before passing urine, the following rules must be observed:
Urine collection rules:
- urine is collected in the morning after sleep;
- before collecting urine, it is necessary to wash or take a shower;
- a sterile container is used to collect urine, which can be purchased at a pharmacy. In children, urine is collected in urinals, which are sold in pharmacies. It is forbidden to squeeze urine from a diaper or diaper;
- for analysis, you need to use urine collected from an average portion;
- urine for analysis can be stored for no more than two hours (at a temperature of 4-18 ° C).
The result of the study is issued the next day, but in emergency cases - after 2 hours.
Deciphering the general analysis of urine:
- increased protein and leukocytes in the urine - almost always indicate pyelonephritis. In this case, women complain of back pain, fever to high numbers, general weakness, chills, nausea, and sometimes vomiting;
- increased protein and red blood cells in the urine - most often a sign of glomerulonephritis. But in the case when the erythrocytes in the urine are fresh, then one can think of urolithiasis.
Daily urine test for protein: how to collect?
One of the most accurate and simple methods, which allows you to determine the daily proteinuria, is a daily urine test for proteinuria.
Daily protein in the urine is carried out to study the filtration function of the kidneys.
Protein can be detected in daily urine in several ways. The simplest and accessible method is chemical, when a protein is detected using special chemical reagents. During the study, a chemical is added to the test tube with urine, which reacts with the protein and denatures it, forming a white ring.
In modern laboratories, special electronic analyzers are used to determine daily proteinuria, which are more sensitive and more accurate than the method described above.
For the study, daily urine is used, which was collected during the day (24 hours).
Urine collection rules:
- urine is collected in a clean three-liter glass jar;
- the first portion of urine at six in the morning is not collected, but poured into the sewer;
- all subsequent portions of urine are collected until six in the morning of the next day;
- the next day, all collected urine should be shaken slightly, then poured into a sterile container of 10-150 ml and delivered to the laboratory, which will be analyzed for daily proteinuria.
The result of the analysis is issued the next day.
Deciphering the daily urine test for protein
Normally, no more than 140 mg of protein fractions should be determined in daily urine. Depending on the amount of protein, proteinuria is divided into three degrees.
Classification of daily proteinuria, table
Increased protein in the urine of a child: signs and how to reduce?
The causes of proteinuria in children are the same as in adults.
External signs of high protein in the urine in children may be as follows: 
- general weakness;
- drowsiness;
- loss of appetite or complete refusal to eat;
- dizziness;
- nausea, sometimes with vomiting;
- fever;
- chills;
- increased sweating;
- joint and muscle pain.
Also, the clinical picture of the disease that caused proteinuria joins the above symptoms.
You can reduce the protein in the urine only by eliminating the cause of its appearance. For example, with pyelonephritis or nephritis, the child is prescribed antibiotics, anti-inflammatory drugs, diet, bed rest and other therapeutic measures.
In the case when proteinuria occurs against the background of influenza or severe GRVI with high temperature bodies, children must be given antiviral and antipyretic drugs.
The well-known TV doctor Komarovsky believes that the appearance of a protein should not panic parents. Newborns are prone to proteinuria, and this is considered the norm, and infants often react with proteinuria to overfeeding. In addition, at small child it is quite difficult to collect urine correctly, so protein in the urine can be determined erroneously.
If a protein is found in your child’s urine test, seek help from a pediatrician or nephrologist, who will prescribe treatment, and, if necessary, refer you to related specialists, such as an infectious disease specialist, endocrinologist, surgeon, and others.
Increased protein in the urine during pregnancy: causes and how to treat?
Elevated protein in the urine during pregnancy (above 0.1 g / l) may be the first and only sign of a violation of the filtering ability of the kidneys. In this case, the woman must be sent for a consultation with a nephrologist.
The patient may be prescribed a repeated urinalysis, a daily urine test for proteinuria, a Zimnitsky test, an ultrasound examination of the kidneys, and other diagnostic methods that will help make an accurate diagnosis. If the cause of the appearance of protein in the urine has not been established, then the pregnant woman will be under the supervision of a nephrologist, who should regularly monitor urine parameters.
In the later stages of pregnancy, when the fetus is actively gaining weight, the kidneys can be squeezed by the pregnant uterus, as a result of which protein appears in the urine. If a woman, in addition to an increased protein in the urine (up to 0.5 g / l), has no other symptoms, then no therapeutic measures are taken, but only her condition and urine parameters are monitored.
In the case when, in addition to proteinuria, the pregnant woman is concerned about edema, arterial hypertension flickering flies before the eyes, shown hospital treatment. This combination of symptoms may indicate the development of late toxicosis, which is dangerous for both the life of a woman and a child.
Protein in the urine after childbirth in a woman: causes
Most often, proteinuria after childbirth is a symptom of kidney disease, namely pyelonephritis, glomerulonephritis, or nephropathy. Moreover, women rarely notice the symptoms of these diseases, because they are busy caring for a child, or trying to cope with the problem on their own.
Also, proteinuria after childbirth can occur due to the labor activity, because attempts are a colossal physical load on the body.
In women who have had late preeclampsia before childbirth, the protein in the urine should return to normal on the 1st-2nd day after childbirth. But it happens that this process is delayed. In this case, the woman remains in the hospital for observation and additional examination.
In addition, the determination of protein in the urine may be erroneous if the material for the study was not collected correctly.
Bens-Jones protein: what does it mean?
Bence-Jones protein is a protein that consists of immunoglobulins type K and X. This type of protein is produced by plasma cells. Since Bence-Jones protein has a small molecular weight, it is easily excreted in the urine.
Determination of Bence-Jones protein in urine is a pathology that is observed mainly in multiple myeloma.
Bence-Jones protein can be detected by heating the urine and adding 3% sulfosalicylic acid to it. When heated, the urine becomes cloudy, which is explained by protein denaturation, and after adding the reagent, it becomes transparent again.
Protein in urine: treatment
The choice of treatment method depends on the cause that caused proteinuria. Treatment can be started only when an accurate diagnosis is established using laboratory and instrumental studies.
During treatment, patients should observe bed or semi-bed rest, as well as adhere to a diet.
In the treatment of proteinuria, the following groups of drugs can be prescribed:
- glucocorticosteroids;
- non-hormonal anti-inflammatory;
- hypotensive;
- cytostatics;
- antibacterial and others.
Let us recall once again that proteinuria is not an independent nosological form, but a symptom of a disease that only a specialist can determine. This symptom should not be ignored. If you get a urinalysis result that indicates an increase in protein levels, make an appointment with a nephrologist or at least a general practitioner.
One of the deviations in the general analysis of urine is the presence of an increased level of protein.
A more accurate determination of the protein composition of urine allows you to get a biochemical study of urine. This condition is referred to as proteinuria or albuminuria.
In healthy people, protein in the urine should be absent, or found in extremely small quantities. Therefore, upon discovery high level protein in the urine requires immediate additional diagnosis.
Protein in urine - what does it mean?
Most often, increased protein in the urine appears during inflammatory processes in the urinary system. This usually means that the filtration function of the kidneys is impaired as a result of partial destruction of the renal pelvis.
However, this is not always the case. Sometimes proteinuria appears with completely healthy kidneys. It could be increased sweating elevated temperature when a person has the flu or increased physical activity, eating a large amount of protein food on the eve of the test.
Physiological and functional proteinuria
Physiological proteinuria is characterized by an increase in the protein content in morning urine to a level not exceeding 0.033 g/l.
And so, why can there be protein in the urine? This contributing factors:
- heavy physical activity;
- excessive insolation;
- hypothermia;
- increased levels of norepinephrine and adrenaline in the blood;
- excessive consumption of protein foods;
- stressful conditions;
- prolonged palpation examination of the kidneys and abdomen.
A physiological increase in the protein content in the urine of a child or an adult is not a cause for concern and does not require special treatment.
Causes of high protein in the urine
A high amount of protein in the urine is one of the undoubted signs of a violation of the normal functioning of the kidneys caused by any disease. An increase in the amount of protein in the urine may be accompanied by various diseases- it is they who are considered the main reason for the increase in protein in the urine.
Such diseases include:
- polycystic kidney disease;
- glomerulonephritis;
- amyloidosis and tuberculosis of the kidneys.
The kidneys can be affected secondarily in certain pathologies of other organs and body systems. More often renal function is impaired:
- gestosis of pregnant women (nephropathy);
- atherosclerosis of the renal arteries.
Another group of reasons explaining why protein appeared in the urine is inflammatory diseases of the lower urinary tract and genital area:
- inflammation of the ureters;
- , vulvovaginitis in women.
These are the most common causes protein in the urine. Only by conducting a more in-depth diagnosis, you can determine why a lot of protein appeared in the urine, and what this means in your particular case.
The rate of proteins in the urine
If the patient is preparing to take a protein test, he should not take acetazolamide, colistin, aminoglycoside and other drugs the day before. They directly affect the concentration of protein in the urine.
Healthy people should not have it. It happens that only a small amount appears. If the concentration in the body is not more than 0.03 g / l, then this is not scary. But if you deviate from this norm, you should worry.
Proteinuria is the detection of protein in the urine at concentrations exceeding 0.033 grams / liter. Taking into account the daily fluctuations in the excretion (excretion) of protein in the urine ( maximum amount occurs in the daytime), to assess the extent of proteinuria, an analysis of daily urine is performed, which makes it possible to determine daily proteinuria.
Based on world medical standards, proteinuria is divided into several forms:
- 30-300 mg / day of protein - this condition is called microalbuminuria.
- 300 mg - 1 g / day - mild proteinuria.
- 1 g - 3 g / day - the average form.
- Over 3000 mg / day - a severe stage of the disease.
In order for the analyzes to be correct and error-free, urine should be collected correctly. As a rule, the collection is made in the morning, when you just woke up.
Symptoms
A temporary increase in the level of proteins in urine does not give any clinical picture and very often occurs without symptoms.
Pathological proteinuria is a manifestation of the disease that contributed to the formation of protein molecules in the urine. With a prolonged course of this condition in patients, regardless of their age (in children and adolescents, in women, men), the following symptoms are present:
- soreness and aches in the joints and bones;
- swelling, hypertension (signs of developing nephropathy);
- , detection of flakes and white plaque in the urine;
- muscle soreness, cramps (especially at night);
- pallor skin, weakness, apathy (symptoms of anemia);
- sleep disorders, consciousness;
- fever, lack of appetite.
If it showed an increased amount of protein, then it is imperative to perform a second study within one to two weeks.
Protein in urine during pregnancy
Detection of protein in urine early dates Pregnancy may be a sign of a latent kidney pathology that a woman had before pregnancy. In this case, the entire pregnancy should be observed by specialists.
Protein in the urine in the second half of pregnancy in small amounts may appear due to mechanical compression of the kidneys by the growing uterus. But it is necessary to exclude kidney disease and preeclampsia in pregnant women.
Why is high protein in urine dangerous?
Proteinuria can be manifested by the loss of various types of protein, so the symptoms of protein deficiency are also varied. With the loss of albumin, the oncotic pressure of the plasma decreases. This manifests itself in edema, the occurrence of orthostatic hypotension and an increase in lipid concentration, which can be lowered only if the protein composition in the body is corrected.
With excessive loss of proteins that make up the complement system, resistance to infectious agents disappears. With a decrease in the concentration of procoagulant proteins, the coagulation ability of the blood is disturbed. What does it mean? This greatly increases the risk of spontaneous bleeding, which is life-threatening. If proteinuria consists in the loss of thyroxin-binding globulin, then the level of free thyroxine increases and functional hypothyroidism develops.
Since proteins perform many important functions (protective, structural, hormonal, etc.), their loss in proteinuria may have Negative consequences on any organ or system of the body and lead to disruption of homeostasis.
Treatment
So, possible reasons protein in the urine has already been clarified and now the doctor must prescribe the appropriate treatment for the disease. To say that it is necessary to treat protein in the urine is wrong. After all, proteinuria is just a symptom of the disease, and the doctor must deal with the elimination of the cause that caused this symptom.
As soon as effective treatment of the disease begins, the protein in the urine will gradually disappear completely or its amount will decrease sharply. Physiological and orthostatic proteinuria do not require treatment at all.
The term "proteinuria" refers to the appearance of any type of protein in the urine in excess of physiological (normal) values.
Detection of an increased level of protein in the urine is the most studied and significant in the practice of a doctor. pathological symptom indicating a malfunction of the urinary system.
In different patients, the severity of proteinuria can vary significantly, depending on the disease underlying it. In addition, the detection of protein in the urine can be observed in isolation or in combination with other changes in TAM (hematuria, leukocyturia, bacteriuria).
- 1 The inner layer, represented by the endothelium, most of which is covered with pores with a diameter of 40 nm. The pores are covered by a diaphragm, so protein filtration at this stage is determined by both the pore size and the state of this diaphragm;
- 2 Three-layer membrane (basal), located outside of the inner layer. Its permeability to protein molecules is determined by its electrical charge and the arrangement of collagen filaments;
- 3 Epithelial lining (podocyte apparatus) located on the urinary side of the basement membrane. This layer is responsible for the process of active filtration using microfilaments.
- 1 Severe psycho-emotional stress;
- 2 Eating a lot of protein;
- 3 Dehydration, electrolyte disturbances;
- 4 Chronic heart failure, hypertension;
- 5 fever;
- 6 Against the backdrop of debilitating exercise(marching proteinuria);
- 7 Against the background of hypothermia.
- 1 Prerenal, or overload, associated with increased protein breakdown and the appearance of an increased concentration of low molecular weight proteins in the blood plasma.
- 2 Renal, associated with damage to the filtration apparatus of the renal glomerulus and / or tubules of the kidneys, where protein molecules are reabsorbed.
- 3 Postrenal, due to the pathology of the underlying urinary tract. Often due to inflammatory exudation.
- 1 plasmablastic leukemia;
- 2 multiple myeloma;
- 3 Connective tissue diseases;
- 4 Rhabdomyolysis;
- 5 Lymphoma with paraproteinemia;
- 6 Hemolytic anemia;
- 7 Macroglobulinemia.
- 1 Glomerulonephritis (acute or chronic);
- 2 Nephropathy in diabetes;
- 3 Nephropathy of pregnancy;
- 4 Amyloidosis;
- 5 Tumors of the kidneys;
- 6 Hypertensive nephrosclerosis;
- 7 Gout.
- 1 Renal glomerular (glomerular) proteinuria, which develops when the cortical substance of the kidney, in which the nephrons are located, is damaged.
- 2 Renal tubular proteinuria, which develops against the background of problems with reabsorption of proteins in the proximal tubules.
- 1 With the loss of the negative charge of the basement membrane, low molecular weight protein molecules (albumin and transferrin) begin to predominate in the urine.
- 2 In case of violation of the integrity of the pores in the membranes, large molecular weight (immunoglobulin G) are determined in the urine.
- 1 Highly selective - excretion of low molecular weight proteins with a mass of up to 70 kDa (mainly albumin);
- 2 Selective - excretion of both low molecular weight and proteins weighing up to 150 kDa;
- 3 Non-selective - isolation of a protein with a mass of 830 to 930 kDa.
- 1 Interstitial nephritis;
- 2 Urinary infections;
- 3 Urolithiasis;
- 4 Toxic effects;
- 5 Wilson's disease;
- 6 Fanconi syndrome.
- 1 Inflammatory pathology of the urinary tract (cystitis, urethritis, prostatitis);
- 2 Bleeding from the urinary tract;
- 3 Polyps of the bladder;
- 4 Tumors of the urinary tract.
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1. History of the discovery of the syndrome
The first information about the change chemical composition urine for some diseases were obtained as early as the 17th century. So, in 1694, the outstanding Leiden doctor F. Dekker first discovered protein in the urine of patients with proven kidney pathology.
In his research, he was able to demonstrate that urine contains a substance that coagulates and coagulates when heated, which in turn leads to the formation of "turbidity".
Based on the experiments, F. Dekker proposed specific methods for detecting this impurity using acetic acid.
As a pathological syndrome, proteinuria was described by D. Cotugno in 1764, identifying it in a patient with acute pyelonephritis. Finally connected proteinuria and renal pathology R. Bright.
To identify the protein, he used a fairly simple and specific technique - heating a small amount urine in a spoon over a flame (the protein precipitated after denaturation). A number of experiments have used nitric acid to detect protein.
R. Bright reliably established the connection of proteinuria with chronic nephritis, which for some time was called "Bright's disease".
2. Limits of norm and pathology
Often, the question of the presence of protein in the urine of healthy individuals can be answered ambiguously. What is considered a normal range for diagnosing pathological proteinuria? There are conflicting data in the medical literature.
With the protein concentration in a single portion of urine, everything is quite simple, normally it should not exceed 0.03 g / l (in children up to a year up to 0.002 g / l, in children older than a year- 0.036 g/l).
The level of daily loss of protein in the urine should normally not exceed 0.15 g / day (up to 100 mg / day Pushkarev I.A. 1985; 150 mg / day Bergstein J., 1999; 200 mg / day B.M. Brenner, 2007) .
At the same time, the calculated concentrations of the level of daily proteinuria based on the given norms in a healthy person (taking into account diuresis up to 1.5 l / day) show the possibility of excreting up to 0.1 gram of protein.
Such discrepancies are explained by the individual and racial characteristics of protein excretion in the urine.
The vast majority of people are characterized by slight proteinuria (about 40-50 mg per day). In 10-15% of the population, the daily excretion of protein in the urine reaches 0.150 g / day without confirmation of the pathology of the urinary system.
The chosen diagnostic method is of great importance for assessing the degree of daily loss of protein in the urine.
Generally accepted methods, such as a test with sulfosalicylic acid or a biuret reaction, do not detect protein in the urine of a healthy population. When a single increase in the level of protein in the urine is detected, patients are often prescribed.
3. Protein composition of urine
To assess proteinuria correctly, you need to have an idea of the qualitative and quantitative composition of normal urine.
In a portion of the urine of a healthy person, up to 200 different proteins can be detected, filtered from the blood or secreted by the epithelial cells of the urinary system.
Approximately 50-70% of urine protein is uroromucoid (uromodulin) - a product of renal tissue synthesis. In the lumen of the renal tubules, uromodulin forms a specific gel-like structure that is impermeable to water, but permeable to ions.
Uromodulin is found in the renal tissue from the 16th day of embryogenesis. In daily urine, it is detected in the amount of 20-100 mg, and its synthesis increases with high salt intake, taking loop diuretics (furasemide, torasemide).
The appearance of tissue proteins may be the result of normal renal excretion and continuous renewal of kidney tissue.
2nd in specific gravity are plasma proteins. When using high-quality diagnostic systems, about 30 plasma proteins can be detected in urine, the leading position among which is albumin.
In the urine, proteins of the tissues of the heart, pancreas, liver, and transplantation antigens can be detected. Damage to the heart tissue in patients is accompanied by myoglobinuria, and some tumors lead to increased excretion of low molecular weight proteins.
Almost all known human hormones are excreted in the urine. In pregnant women, proteins secreted by placental tissues can be detected in the urine.
4. Mechanism of appearance of protein in urine
Urine formation occurs in the main structural element of the kidney - the renal glomerulus (a network of arterial capillaries enclosed in a capsule).
Blood entering the capillaries of the glomerulus is filtered through a special glomerular membrane with the formation of primary urine. The glomerular filtration membrane has a rather complex structure and includes:
In a healthy person, the glomerular filter can pass proteins of a certain size (no more than 4 nm, weighing no more than 70 kDa). Proteins such as serum albumin, myoglobin, prealbumins, lysozyme, microglobulins, etc. are freely filtered.
In addition to size, the charge of the protein molecule plays an important role in the filtration process. The basement membrane is normally negatively charged and does not allow active filtration of plasma proteins that have the same charge.
Figure 1 - The structure of the nephron
If small plasma proteins manage to pass the renal filter, they are almost completely absorbed in the renal tubules.
Summarizing the above, physiological protein excretion is the result of the interaction of glomerular and tubular mechanisms, and damage to any of the departments of the nephron can lead to proteinuria.
Identification of transient or permanent proteinuria in a person requires a thorough examination. Next, we turn to the study of the main reasons for the increase in the level of protein in the urine.
5. Functional proteinuria
Functional proteinuria is not associated with renal tissue damage. It is based on a transient violation of protein filtration. This condition may occur when:
In infants, dehydration proteinuria is often found, which is based on violations of the feeding regimen, toxicosis, diarrhea, and vomiting. After removal of the provoking factor, such proteinuria stops.
In adolescents, the so-called orthostatic proteinuria can be detected - an increase in the excretion of protein in the urine during the transition to a standing position. Children predisposed to orthostatic proteinuria are diagnosed with active growth, low muscle mass, kyphosis, lumbar lordosis, low blood pressure, and absolutely normal renal function.
Proteinuria occurs when a teenager is standing. Lordosis of the spine leads to the fact that the anterior surface of the liver goes down and slightly presses the inferior vena cava. Stagnation of blood in the renal veins and provokes the release of protein in the urine.
In physiological proteinuria, the largest proportion is low molecular weight proteins (up to 20 kDa), for example, Ig, 40% proteins with a high mass (65 kDa), 40% are uromodulin.
6. Pathological proteinuria
Pathological proteinuria develops when the renal glomeruli, where filtration occurs, or the renal tubules, where reabsorption of protein molecules occurs, are damaged.
Depending on the level of damage, three types of pathological proteinuria can be distinguished:
6.1. prerenal
Prerenal proteinuria is based on the appearance in the patient's blood plasma of proteins with a small molecule size, which can pass through a healthy renal filter and enter the urine in large quantities.
The appearance of such proteins in the plasma is associated either with their increased synthesis or with the breakdown of tissue structures and cells. This condition may occur when:
Most often, this type of proteinuria is due to an increase in the blood of light chains of Ig (Bence-Jones protein), myoglobin, hemoglobin, lysozyme.
Congestive forms of prerenal proteinuria are possible, which occur in decompensated heart disease, metastases, and tumors of the abdominal cavity.
In a separate category, neurogenic prerenal proteinuria can be distinguished, which can be triggered by an epileptic seizure, traumatic brain injury, hemorrhage, autonomic crisis.
6.2. Renal
IN this case an increase in the level of protein in the urine is associated with damage to the renal parenchyma or renal interstitium. This is typical for the following conditions:
Depending on the location of the damage, the composition and volume of proteins excreted in the urine changes, which makes it possible to distinguish between:
6.2.1. Glomerular injury
With damage to the renal glomeruli, changes in the glomerular type are recorded in the urine:
Thus, the nature of damage to the renal filter affects the ability to pass protein molecules of different sizes and masses.
That is why, according to the composition of uroproteins, proteinuria is distinguished:
To determine the degree of selectivity, a special index is used, which is the ratio of isolation of proteins with high mass to low molecular weight (usually the ratio of IgG/albumin).
A ratio of up to 0.1 (selective) indicates a filtration defect associated with a violation of the ability to retain negatively charged molecules. An increase in the index of more than 0.1 indicates the non-selectivity and permeability of the filter pores for macromolecules.
Determination of the degree of selectivity of glomerular proteinuria is important for the development of patient management tactics.
The selective nature of protein loss in the urine indicates minimal damage, therefore, in such patients, the effectiveness of glucocorticosteroids is high.
Non-selectivity is associated with more severe changes in the renal filter (membranous nephropathy, glomerulosclerosis, proliferative glomerulonephritis), in the treatment, as a rule, resistance to steroids is observed.
An increase in glomerular hydrostatic pressure can also lead to increased protein filtration, which is a variant of glomerular proteinuria.
6.2.2. tubular protein loss
It develops against the background of impaired protein reabsorption in the renal tubules and is manifested by the release of low molecular weight proteins (weight below 40 kDa), which are normally completely reabsorbed.
Tubular proteinuria, as a rule, does not exceed 2 g / 1.73 mx2 / day.
Pathologies associated with tubular protein loss include:
Indicators of tubular proteinuria are B2-microglobulin, retinol-binding protein and/or alpha1-microglobulin.
The level of excretion of B2-microglobulin has the greatest diagnostic value. An increase in the level of albumin in the urine with a normal content of B2-microglobulin indicates damage to the glomeruli, while the predominance of B2-microglobulin indicates tubular pathology. However, one should not forget about the possibility of an erroneous result of the analysis.
6.3. Postrenal
Postrenal proteinuria is caused by the ingestion of an inflammatory protein-rich exudate into the urine and is associated with damage to the underlying urinary tract. This condition may occur when:
Figure 1 - Differential diagnosis of proteinuria. Source -V.L. Emanuel. Problems of the pathology of the urogenital system // Journal of laboratory medicine. No. 7, 2015.
7. Gradations of proteinuria
By the amount of protein excretion, it is advisable to distinguish between the variability of proteinuria, which ranges from microproteinuria to a high, nephrotic degree (above 3 g / day).
The term MAU (microalbuminuria) means the excretion of albumin in the urine in an amount higher than physiological norm, but below the sensitivity of standard test systems.
It is customary to talk about MAU with a daily loss of 10 mg to 300 mg of albumin. UIA may be the only one early sign damage to the glomerulus, for example, in diabetic nephropathy.
MAU appears long before the start of a decrease in the level of GFR (glomerular filtration rate). Microalbuminuria also occurs in hypertension, kidney transplant rejection.
Low grade proteinuria (300 mg -1 g/day) can be detected in acute urinary tract infections, urinary tract obstruction, urolithiasis, and nonspecific nephritis.
Moderate loss of proteins (1 g - 3 g / s) develops with acute tubular necrosis, glomerulonephritis, hepatorenal syndrome, amyloidosis.
A large loss of protein in the urine (more than 3 g / s) is actually always associated with a violation of the glomerular filter and a change in the "size-charge ratio" of proteins and membranes.
8. Clinical manifestations
Proteinuria, occurring in a mild form, usually does not have any clinical manifestations or masked by the symptoms of the underlying pathology.
With a significant increase in the concentration of protein in the urine, foaming during urination is observed. Such "foam" remains long enough.
A constant and significant loss of proteins in the urine can lead to the development of edema of the face, limbs, and abdomen.
9. Kidney failure
Proteinuria is one of the most significant risk factors for the formation and progression of CKD (chronic kidney disease). The relationship between the increase in protein loss in the urine and the rate of decline in kidney function has been proven.
In one of the latest meta-analyses (Stoycheff, 2011), the role of proteinuria as an independent risk factor for CKD progression was once again proven.
Proteinuria (including MAU) are risk factors for the development of complications from the cardiovascular system.
In international expert recommendations, a normogram is used to determine the risk of an unfavorable prognosis for the development of CKD and renal failure (Figure 2). The higher the level of proteinuria, the higher the risk of fatal outcomes.
Fig. 2. Nomogram of risk of poor prognosis KDIGO-2012, 2013: green - low risk (if there are no other markers of renal pathology or the pathology itself), yellow - moderate risk, orange - high risk, red - very high risk
10. Treatment tactics
The tactics of managing a patient with proteinuria directly depend on the cause, the risk of an unfavorable outcome, the prognosis, which determines the need for dynamic monitoring by a therapist or a nephrologist.
