Relative density of urine. Determination of specific gravity of urine. Preparation, analysis

1. Amount of urine

Diuresis is the volume of urine produced over a certain period of time (daily or minute diuresis).

The amount of urine delivered for general analysis (usually 150–200 ml) does not allow any conclusions to be made about disturbances in daily diuresis. The amount of urine delivered for general analysis affects only the ability to determine the specific gravity of urine(relative density).

For example, to determine the specific gravity of urine using a urometer, at least 100 ml of urine is required. When determining specific gravity using test strips, you can get by with a smaller amount of urine, but not less than 15 ml.

2. Urine color

Normal urine is yellow in color..

Saturation yellow color urine depends on the concentration of substances dissolved in it. With polyuria, the dilution is greater, so the urine has a lighter color; with a decrease in diuresis, it acquires a rich yellow tint.

The color changes when taking medications (salicylates, etc.) or eating certain foods (beets, blueberries).

Pathologically changed color of urine occurs with hematuria (the type of meat slop), bilirubinemia (the color of beer), with hemoglobinuria or myoglobinuria (black color), with leukocyturia (milky white color).

3. Transparency of urine

Normally, freshly released urine is completely clear..

Turbidity of urine is due to the presence in it of a large number of cellular formations, salts, mucus, bacteria, and fat.

Cloudy urine may also indicate microhematuria, but in most cases it is a sign of infection (ie, bacteriuria). Note: visual analysis urine can be used as a preliminary test for infection urinary tract in patients without symptoms. In the course of the studies, it turned out that the sensitivity of visual examination of urine samples for diagnosing bacteriuria is 73%.

4. Urine smell

Normally, the smell of urine is mild and nonspecific..

When urine decomposes by bacteria in the air or inside Bladder, for example, in the case of cystitis, an ammonia smell appears.

Rotted urine that contains protein, blood, or pus, such as bladder cancer, causes the urine to smell like rotten meat.

If there are ketone bodies in the urine, the urine has a fruity odor, reminiscent of the smell of rotting apples.

5. Urine reaction

Normal urine reaction is acidic.

Fluctuations in the pH of urine are determined by the composition of the diet: a meat diet causes an acidic urine reaction, a vegetable diet causes an alkaline reaction. With a mixed diet, mainly acidic metabolic products are formed, so it is believed that the urine reaction is normally acidic.

Before carrying out a general analysis, urine should be stored in a cold room and for no more than 1.5 hours. When standing in a warm room for a long time, urine decomposes, ammonia is released and the pH shifts to the alkaline side. The alkaline reaction underestimates the relative density of urine. In addition, white blood cells are quickly destroyed in alkaline urine.

An alkaline reaction of urine is characteristic of chronic urinary tract infection, and is also observed with diarrhea and vomiting.

The acidity of urine increases in feverish conditions, diabetes mellitus, tuberculosis of the kidneys or bladder, and renal failure.

6. Specific gravity of urine (relative density of urine)

Normally, the morning urine sample should have a specific gravity in the range of 1.018-1.024.

Relative density of urine (the density of urine compared with the density of water) reflects the functional ability of the kidneys to concentrate and dilute and can be used as a screening test for mass examinations of the population.

Figures of relative density of morning urine equal to or exceeding 1.018 indicate normal concentrating ability of the kidneys and eliminate the need to study it using special methods. High or low figures for the specific gravity (density) of morning urine necessarily require clarification of the reasons behind these changes.

Analysis transcript

High specific gravity of urine

The relative density of urine depends on the molecular weight of the particles dissolved in it. Protein and glucose increase the specific gravity of urine. For example, diabetes mellitus can be suspected only by one general urine test with relative density figures of 1.030 and above against the background of polyuria.

Low specific gravity of urine

The process of urine formation is regulated by the concentrating mechanism of the kidneys and the antidiuretic hormone (ADH) produced by the pituitary gland. In the presence of antidiuretic hormone, more water is absorbed and as a result, a small amount of concentrated urine. Accordingly, in the absence of antidiuretic hormone, water absorption does not occur and large volumes of diluted urine are released.

There are three main groups of reasons for the decrease in specific gravity in a general urine test:

1. excess water consumption
2. neurogenic diabetes insipidus
3. nephrogenic diabetes insipidus

1. Excessive water intake (polydipsia) causes a decrease in the concentration of blood plasma salts. To protect itself, the body secretes large volumes of diluted urine. There is a disease called involuntary polydipsia, which, as a rule, affects women with unstable mental health. The leading signs of involuntary polydipsia are polyuria and polydipsia, low relative density in a general urine test.

2. Neurogenic diabetes insipidus- insufficient secretion of an adequate amount of antidiuretic hormone. The mechanism of the disease is the inability of the kidneys to retain water through concentrated urine. If the patient is deprived of water, diuresis almost does not decrease and dehydration develops. The relative gravity of urine may drop below 1.005.

The main causes of neurogenic diabetes insipidus:

Hypopituitarism is a failure of the pituitary gland or hypothalamus with a decrease or cessation of production of tropic hormones of the anterior pituitary gland and antidiuretic hormone.

• The most common cause of decreased specific gravity of urine is idiopathic neurogenic diabetes insipidus. Idiopathic neurogenic diabetes insipidus is most often found in adults in at a young age. Most of the underlying disorders leading to neurogenic diabetes insipidus can be identified by associated neurological or endocrinological symptoms (including cephalalgia and visual field impairment or hypopituitarism).
• Other common reason decrease in the specific gravity of urine - damage to the hypothalamic-pituitary region due to head trauma, neurosurgical intervention in the pituitary gland or hypothalamus. Or damage as a result of a brain tumor, thrombosis, leukemia, amyloidosis, sarcoidosis, encephalitis after an acute infection, etc.
• Taking ethyl alcohol is accompanied by reversible suppression of ADH secretion and short-term polyuria. Diuresis occurs 30-60 minutes after taking 25 g of alcohol. The volume of urine depends on the amount of alcohol taken in a single dose. Continuous use does not lead to sustained urination, despite the existence of a constant concentration of alcohol in the blood.

3. Nephrogenic diabetes insipidus- a decrease in the concentrating ability of the kidneys, despite the normal content of antidiuretic hormone in the blood.

The main causes of nephrogenic diabetes insipidus:

• The most numerous subgroup among patients with nephrogenic diabetes insipidus consists of persons with parenchymal kidney diseases (pyelonephritis, different kinds nephropathies, tubulointerstitial nephritis, glomerulonephritis) and chronic renal failure.
• Metabolic disorders:
  • Conn's syndrome- combination of polyuria with arterial hypertension, muscle weakness and hypokalemia. The relative density of urine can range from 1003 to 1012).
  • Hyperparathyroidism- polyuria, muscle weakness, hypercalcemia and nephrocalcinosis, osteoporosis. The relative density of urine decreases to 1002. Due to the significant content of calcium salts, urine is often white.
• Rare cases of congenital nephrogenic diabetes insipidus. The relative gravity of urine may drop below 1.005.

The specific gravity of urine is determined as the ratio of its density to the density of simple distilled water. The density of urine is often not constant throughout the day because it depends on the total amount of fluid a person consumes as well as their metabolic rate.

However, the relative density of urine can provide doctors with some clues about problems occurring in the human body.

The specific gravity of urine is also called its relative density. These indicators indicate problems in the functioning of the kidneys, since these organs are responsible for diluting and concentrating urine.

When the body performs its functions normally, the relative density varies depending on the amount of food taken and the volume of liquid.

Fluctuations in the specific gravity of urine are detected using several types of tests. The most commonly used methods are: Zimnitsky's test, test with dry food and test with water load.

Only by assessing the density of urine excreted during the collection of each sample can average data be derived that will help doctors understand the reasons for the decrease or increase in urine density.

Norm and deviations

The process of urine density usually consists of three stages. The first one is filtration. Second stage - reabsorption. It involves the reverse process of absorption. It occurs in the nephron tubules into which urine flows.

Third stage - tubular secretion. During this process, toxic metabolic products are released from the blood under the influence of special enzymes.

Thus, substances that change its density enter the urine.

The specific gravity of urine varies depending on the total volume of substances that are dissolved in it. The higher the concentration of urine, the greater its density. The last indicator is determined by salts, as well as protein, leukocytes, bilirubin and others.

At different times of the day normal indicators densities may vary from 1001 to 1040 g/l. Only a doctor can calculate deviations in this case by interviewing the patient and approximately finding out what is the reason for the increase or decrease in concentration.

If the analysis is carried out on the basis of a study of the morning urine sample, then its normal density varies from 1015 to 1020 g/l. However, in the morning urine can be very saturated, since liquid does not enter the human body at night.

Deviations in the density of urine can be caused not only by characteristics of the human body. Quite often, even simple seasonal changes can be the cause. IN winter time The density of urine in a healthy person is usually lower, while in summer the density of urine is higher.

Specific gravity of urine 1010 g/l

A urine density of 1010 g/l is borderline. Quite often it is used as a guide.

If, upon receiving test results, the density of urine does not exceed 1010 g/l, this may indicate hyposthenuria.

If the density of urine more than 1010 g/l, this speaks of hypersthenuria.

If The density of urine and blood are the same- 1010 g/l, then the doctor may suspect isosthenuria.

Relative density in women

In women, unlike men, the density of urine is slightly lower, but it can also fluctuate depending on individual characteristics body during the day.

Normal urine density in women and girls over 12 years of age varies from 1010 to 1025 g/l.

Any changes in urine density should be discussed with your doctor as they could be caused by external factors, and did not result from health problems.

In pregnant women

Pregnant women may experience an increase in urine density during toxicosis, when the body quickly loses fluid without having time to restore its balance. But a sharp decrease in density may also be noticeable, especially in those moments when the swelling that developed during the previous day subsides by morning.

If the expectant mother is not susceptible to toxicosis, usually the density of her urine may vary from 1010 to 1030 g/l. But this indicator is not a reference.

Normal indicators for a child under one year old

The density of urine in newborns is quite low. Indicators are considered normal from 1008 to 1018 g/l.

In six-month-old children, normal urine density values ​​are within the range from 1002 to 1004 g/l.

In children from six months to one year, the indicators are considered normal. from 1006 to 1010 g/l.

It can be quite difficult to get required amount urine, especially in children early age. A minimum of 50 ml of urine is required for the test.

Urine density in children aged 2 years

At the age of 2–3 years in children, the normal boundaries of urine density shift slightly. That is, usual for healthy child indicators are considered within from 1010 to 1017 g/l.

But it is worth considering that, as in adults, these indicators can change throughout the day, as well as when consuming a large or insufficient amount of liquid.

In children from 3 years old

In children from 3 to 5 years old, density is considered the norm. from 1010 to 1020 g/l.

A child from 7 to 8 has normal density indicators - from 1008 to 1022 g/l.

Closer to 12 years, or more precisely from 10 to 12 years, the density of a child’s urine approaches normal levels for an adult. Indicators are considered normal from 1011 to 1025 g/l.

At the age of 12 years, the normal density of urine in a child becomes the same as in an adult, that is from 1010 to 1022 g/l.

If urine density is below normal

A decrease in urine density below the normal level of 1010 g/l indicates the following diseases:

• diabetes insipidus;
• renal failure.

In some cases, this effect occurs when taking diuretics and drinking plenty of fluids. Typically, a decrease in the specific gravity of urine is called hyposthenuria. This phenomenon implies a violation of the concentration function.

Hyposthenuria can also occur in healthy people, after nutritional dystrophy or when edema subsides.

If the density is higher than normal

If the density of urine is higher than normal, that is, above the upper limit of 1030 g/l, then there may be several reasons for this phenomenon.

First of all, these can be diseases such as:

• diabetes;
• glomerulonephritis;
• pyelonephritis;
• cystitis;
• other kidney or urinary tract diseases.

Often, the density of urine increases in cases where a person takes antibiotics or diuretics in large dosages.

Also, increased density of urine is observed with low, insufficient fluid intake, with its sudden loss, due to vomiting, diarrhea or profuse sweating.

An increase in urine density is called hypersthenuria.

Relative density is a measure that helps assess kidney function based on urine content. The amount of fluid moving through the body is unstable. Its volume indicators vary depending on various circumstances:

• daily time;
• eating salty and spice-rich foods;
• volume of water in food;
• sweating during exercise.

The formation of primary urine occurs after blood is filtered by capillary cells. Per day, from 150 liters of primary urine, approximately 2 liters of secondary urine are formed.

The main reason for the decrease in urine density is a failure in the production of vasopressin, a peptide hormone of the hypothalamus.

For example, in certain forms of diabetes insipidus, the amount of urine excreted by the patient per day can be up to 20 liters, when the norm is 1.5 liters. This is due to the virtual absence of vasopressin in humans.

Antidiuretic hormone (ADH) accumulates in the pituitary gland and then enters the blood channel. Its main functions:

• fluid retention in the human body;
• stenosis of the lumen of the arteries.

ADH improves fluid reabsorption, regulates urine concentration, and reduces its quantity. By normalizing the abundance of water in the body, vasopressin increases the permeability of fluid in the kidney canals.

The accumulation of solids in urine varies, directly depending on the composition of the blood plasma. Humoral and nervous biomechanisms are responsible for this process.

The fact that a person has a low specific gravity of urine is often discovered when determining pathologies that are in no way related to the urinary organs. Establishing the relative density is done after examining a general analysis of urine, along with the number of leukocytes, as well as products of protein metabolism.

The low specific gravity of the liquid is determined by performing special tests:

• study according to Nechiporenko;
• Volhard diagnostics.

Carrying out these measurements helps to obtain the most accurate results of relative density and even roughly establish the cause of hyposthenuria.

The main instrument with which tests are carried out is a urometer, which determines density.

Analysis includes several steps:

1. The biological fluid is placed in a cylindrical vessel. When a little foam has formed, it is removed with filter paper.
2. The urometer is lowered into the urine so that the device does not touch the walls of the container.
3. After the urometer stops oscillating, the specific gravity along the border of the lower meniscus is counted.

To get the most accurate result, it is necessary to take into account the air temperature, using an average of 15 °C as a basis.

Causes

The specific gravity of the released liquid is considered to be reduced at a level of up to 1.01. This state of affairs indicates a decrease in the working activity of the kidneys. The ability to filter harmful elements is significantly reduced, which can cause slagging in the body and the appearance of various complications.

However, this indicator is sometimes considered the norm. For example, during pregnancy in women, hyposthenuria often develops as toxicosis manifests itself. In this condition, disturbances in the functioning of the gastrointestinal tract sometimes occur, causing water retention in the body. Expectant mothers suffer from urinary disorders - urine is emitted frequently, but in small quantities.

Violation of the specific gravity of urine in women expecting the birth of a baby also occurs for the following reasons:

• Changes in the hormonal field. Increased level female hormones cause a certain imbalance of other biological substances.
• While carrying a child, many factors appear in the body that affect the decrease in the active functioning of the kidney. This is an enlarging uterus that puts pressure on the pelvic organs. Blood vessels also dilate, which increases the load on the kidneys.

After the baby is born, a urine sample is taken to determine the function of the kidneys and assess the overall health status. The density of liquid discharge, as a rule, in a baby is no more than 1.015-1.017. These data remain for the first month, and then begin to increase after changing the diet.

Pathological conditions in which a decrease in the specific gravity of urine is observed:

• nephrogenic diabetes insipidus;
• polydipsia (extreme thirst);
• neurogenic diabetes insipidus.

These are diseases in which the production of vasopressin decreases and fluid reabsorption does not occur. With any urination, a considerable amount of urine with a small content of urea and its salts is released.

Specific gravity of urine is one of the key parameters of the general analysis. WHO has established standards for the results of specific gravity studies for various categories of citizens: children, men, pregnant women, etc.

The relative density of urine can change quite quickly under the influence of the following factors:

• Diet;
• Drinking regime;
• Intensity of physical activity;
• Sweating intensity.

Any process of removal and accumulation of fluid in the body capable of influencing on the specific gravity of urine.

How is it defined?

Laboratory research is carried out using a special device - urometer (hydrometer). Measuring scales allow you to determine the specific gravity of urine in the range from 1,000 to 1,060 g/l.

50-100 ml of urine is carefully collected into a cylinder, trying to avoid foaming. If foam still appears, it is removed with filter paper. The device is immersed in urine so that its upper part remains above the liquid level.

When the urometer stops diving on its own, you need to push it slightly with your fingers, since it does not sink completely. The movement of the hand creates slight vibrations. It is appropriate to determine the relative density of urine only after the fluctuations have completely stopped.

The urometer should not come into contact with the walls of the container, so choose a cylinder with a diameter larger than the widest part of the device.

When a small amount of urine is provided for analysis (20-50 ml), it is diluted with distilled water to the required volumes and measure in in the prescribed manner. The last two digits of the established indicator are multiplied by the degree of dilution.

It is possible to determine the parameters of the specific gravity of urine, even if only a few drops were collected for analysis. In this case, the liquid mixture method is used.

A mixture of benzene and chloroform is poured into a cylindrical container and the collected urine is pipetted. If drops of urine sink, then its relative density is higher than the parameters of the mixture; if the drops fall on top, then the density is lower.

By adding small amounts of chloroform or benzene to the mixture, the mixture is adjusted until a drop of test urine is level in the middle of the container. “Averaging” a drop means that the specific gravity of the urine is equal to the specific gravity of the solution, which is easy to determine in the laboratory.

Getting started laboratory tests, must be observed rules for its conduct:

1. Ambient temperature = 15 degrees Celsius (3 degrees deviation is acceptable);

Some urometers are calibrated to measure at 20 or 22 degrees. You need to pay attention to the instructions on the device body.

2. Lack of protein or glucose in the material;
3. , odor, clarity and acidity of urine.

Functional tests

When deviations from the norm are detected by OAM, as a rule, additional functional tests are prescribed. and concentration test allow you to assess the general condition of the kidneys, their ability to concentrate and excrete with salts.

According to Zimnitsky

Laboratory testing evaluates the patient's kidney function without using a drinking diet. A person collects 8 portions of urine, urinating every 3 hours within one day.

A urometer is used to examine the relative density of each portion of urine and the resulting volume. The result of the study shows an objective difference between day and night, while nighttime diuresis should be about 1/3 of daytime.

Read our article on how to correctly collect a urine test according to Zimnitsky.

Concentration

Preparing the patient for the test involves on a daily basis from his diet, drinking fluids in any form. Urine is collected every 4 hours. Each portion is examined using a urometer and the results obtained are analyzed.

If the specific gravity falls within the range of 1.015-1.017 g/l, this means that the patient’s kidneys cannot cope with their main function and do not concentrate urine in the required volume. This condition is called isosthenuria.

What are the normal ranges for urine specific gravity?

During the day, the relative density of urine fluctuates and deviates from the norm within 0.001-0.005 g/l. Average values for people of different categories:

• Newborn up to 5 days - 1.008-1.018;
• From 5 days to 2 years - 1.002-1.004;
• Child 2-3 years old - 1010-1.017;
• Child 4-5 years old - 1.012-1.020;
• Child 6-17 years old - 1.011-1030;
• Adult - 1,010-1,025;
• Pregnant woman - 1.003-1.035.

The most informative There will be an analysis of night or first morning urine, since during sleep a person’s breathing slows down, the intensity of sweating is reduced and fluid does not come from outside.

Deviation from the norm: causes and consequences

High and low density urine in medical terminology is called hypersthenuria and hyposthenuria, respectively.

Both conditions indicate a disruption of normal water-salt metabolism in the body and can often be detected in the human body functional diseases and pathology.

Hypersthenuria

Increased specific gravity of urine usually accompanied by quite obvious swelling. This symptom may indicate the development of glomerulonephritis or.

In addition, hypersthenuria is characteristic of various endocrinological diseases, when hormonal dysfunction reduces fluid levels in the human body.

Causes of hypersthenuria:

• Physiological processes associated with significant loss of fluid (profuse vomiting and diarrhea, increased sweating, bleeding, large-area burns, etc.).
• Injuries to the abdomen, back, intestinal obstruction.
• Toxicosis in women during pregnancy.
• Chronic diseases of the urinary system.
• Taking antibiotics in high dosage.
• Endocrine diseases with disruption of natural metabolism.

Physiological hypersthenuria does not require medical intervention. The specific gravity of urine will return to normal levels as soon as the body replaces fluid losses.

Symptoms of hypersthenuria:

• Reducing the volume of urine excreted.
• urine.
• Increased odor of urine.
• Swelling.
• Weakness, drowsiness and fatigue.
• Girdle pain in the abdomen and back.

As noted above, an increase in urine weight may occur due to presence of glucose or protein in urine. If one of these components is detected in the urine, additional functional studies are prescribed.

Hyposthenuria

The concentration of solids in the urine is below normal, decrease in its relative density occurs due to an increase in fluid intake or the development of pathological processes within the body.

Causes of hyposthenuria:

• – acute inflammatory process in the kidneys.
• Chronic diseases of the urinary system.
• Not diabetes mellitus of different nature(neurogenic, nephrogenic, during pregnancy, etc.).
• Increasing fluid intake.

Symptoms of hyposthenuria:

• Increased volume of urine excreted.
• Light colored urine.
• Paleness of the skin.

Often hyposthenuria is asymptomatic and deviations from the norm can only be identified by performing a general urine test.

How to normalize the specific gravity of urine?

When abnormal urine specific gravity is caused by physiological reasons, then normalization occurs without medical intervention. As soon as the body replenishes fluid losses or removes excess fluid, the relative density indicator will return to normal.

If hypersthenuria or hyposthenuria manifests itself against the background of diseases, then it is possible to normalize the specific gravity of urine only through therapeutic intervention or eliminating the pathological cause.

What is encrypted in the clinical urine analysis forms, see in the video:

A person has to deal with various medical services throughout his life. This may be a consultation with a medical specialist, examination of any biomaterials, examination internal organs, taking various medications. General analysis Absolutely all people test urine; it is prescribed to all people - from infants to pensioners. This is the most common and at the same time informative method of examining urine.

General urinalysis: what kind of study is this?

The analysis data is an indicator of kidney function, so at the slightest suspicion of kidney dysfunction, doctors prescribe this test. In addition, the results of the analysis may indicate other pathological processes in the body. This method can detect improper functioning of organs by determining the general properties of urine and microscopy of urinary sediment. The main parameters by which the doctor draws conclusions about the patient’s condition are the following:

• urine color;
• its transparency;
• urine density;
• presence of protein;
• acidity;
• glucose indicators;
• what is the patient's hemoglobin level?
• bilirubin;
• urobilinogen;
• nitrites;
• Availability ;
• epithelium;
• red blood cell count;
• leukocytes;
• what bacteria are in the urine;
• cylinders.

This study is prescribed quite often for patients with kidney pathologies to monitor the dynamics of changes in the functioning of the excretory system and the effectiveness of the medications used. A healthy person should ideally undergo this test 1-2 times a year for timely detection of pathologies.

What are the rules for collecting analysis?

The research must be carried out with utmost precision. It must be ensured from the beginning of urine collection to the final results. Before collecting urine, it is necessary to carry out hygiene of the relevant organs. Please note that various food jars or containers are not suitable for analysis. To collect biomaterial, a special container is required, used only for these purposes. You can buy it at any pharmacy.

In the evening before the test, you need to limit the consumption of foods that can color the urine: beets, carrots and others. In addition, you need to monitor the use of various medications the day before, as they can distort test results. During menstruation, the results may also be false, so you need to wait until the end of this period.

You should not drink alcohol the evening before the test. The content of trace elements in urine can change significantly.

What can be revealed using this analysis?

A general urine test is prescribed to determine the condition of the body if certain pathologies are suspected. This analysis is prescribed when diseases of the urinary system occur, to determine the dynamics of the disease and control it. Analysis helps prevent timely possible complications, and also shows the effectiveness of the treatment. This study is also often used in examinations of people undergoing medical examinations.

Determination of urine density

The density of urine is the relative ratio of the densities of two materials, one of which is considered as a standard. IN in this case The sample is distilled water. The density of urine is usually variable. The reason is that the density changes over the course of a day, this is explained by the uneven excretion of metabolic products dissolved in the urine.

When filtering the blood, the kidneys produce primary urine, most of which is reabsorbed and returned to the bloodstream. Based on the process described, the kidneys make a concentrate of secondary urine. The process described above is called concentration. If the latter is disrupted, this will lead to a decrease in the relative density of urine. Diabetes insipidus, some variants of chronic nephritis and other diseases can impair the concentration function.

If protein, sugar, leukocytes, red blood cells, and the like appear in the urine, this helps to increase the density of urine. The relative density of urine, or more precisely, its average value depends on the age of the person. The concentration function of the kidneys also depends on age. Generally speaking, these two concepts are closely related.

Physiology of urine density

The density of urine, or more precisely, the process of its formation, consists of three stages. These are filtration, reabsorption and tubular secretion.

The first stage - filtration - occurs in the Malpighian corpuscle of the nephron. It is possible due to the high hydrostatic pressure in the glomerular capillaries, which is created due to the fact that the diameter of the afferent arteriole is larger than the efferent arteriole.

The second stage is called reabsorption or, in other words, absorption into reverse side. It is carried out in the twisted and smooth tubules of the nephron, where, in fact, primary urine enters.

The final, third stage of urine formation is tubular secretion. The cells of the renal tubules, together with special enzymes, actively transfer toxic metabolic products from the blood capillaries into the lumen of the tubules: urea, uric acid, creatine, creatinine and others.

Normal urine relative density

The relative density of urine normally has a wide range. Moreover, the process of its formation will be determined by normally functioning kidneys. The relative density of urine tells a specialist a lot. The rate of this indicator will fluctuate many times during the day. This is due to the fact that from time to time a person eats different foods, drinks water and loses fluid through sweating, breathing and other functions. IN different conditions the kidneys excrete urine with a density of: 1.001 - 1.040. This is considered to be normal urine density. If a healthy adult drinks a sufficient amount of water, then the relative density of urine, the norm of which is indicated above, in the morning may have the following indicators: 1.015 - 1.020. Morning urine can be very rich because no fluid enters the body at night.

The density of urine is normal if its color is straw-yellow, transparent and has a mild odor. Her reaction should range from 4 to 7.

Why is hypersthenuria dangerous?

If a person has increased urine density, this indicates that certain pathological processes are occurring in the body, which in one word are called “hypersthenuria”. Such a disease will manifest itself as an increase in edema, in particular with acute glomerulonephritis or insufficient blood circulation in the kidneys. If huge extrarenal fluid losses have occurred. This includes diarrhea, vomiting, large blood loss, burns over a large area, swelling, abdominal injuries, and intestinal obstruction. Hypersthenuria will also be indicated by the appearance in the urine large quantity glucose, protein, drugs and their metabolites. The cause of this disease is also toxicosis during pregnancy. If you took a test that turned out to be high (more than 1030), this result will indicate hypersthenuria. Such results should definitely be discussed with your doctor.

High urine density does not pose a great danger to human life. But it comes in two types:

1. Kidney pathology, for example, nephrotic syndrome.
2. Absence of primary renal pathology (glucosuria, hypovolemic conditions, in which the reabsorption of water in the tubules increases as compensation, and therefore urine concentration begins).

What does hyposthenuria indicate?

Hyposthenuria is the opposite of hypersthenuria. It is characterized reduced density urine. The cause is acute damage to the renal tubules, diabetes insipidus, permanent renal failure or malignant hypertension.

Hyposthenuria indicates that there is a violation of the concentrating ability of the kidneys. And this, in turn, indicates renal failure. And if you are diagnosed with this disease, it is advisable to immediately contact a nephrologist who will prescribe you timely and necessary treatment.

Urine density standards for children

As discussed in this article above, urine density standards are different for each age. An adult's urine test is significantly different from a child's. It can vary in many ways, but its main difference is in the standards. The relative density of urine in a child must meet the following standards:

For a one-day-old baby, the norm is from 1.008 to 1.018;

If the baby is about six months old, the norm for him will be 1.002-1.004;

Between six months and one year of age, normal urine relative gravity ranges from 1.006 to 1.010;

Between the ages of three and five, urine density limits will range from 1.010 to 1.020;

For children who are approximately 7-8 years old, the norm is 1.008-1.022;

And those who are between 10 and 12 years old, their urine density should correspond to the norm of 1.011-1.025.

It can be very difficult for parents to collect urine from their child, especially if he is very small. But in order to determine the density of urine, at least 50 ml must be delivered to the laboratory where such an analysis is carried out.