Determination of specific gravity of urine. Density of urine. Interpretation of a general urine test. Urinalysis: how it is done

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The density or specific gravity of urine characterizes the amount of substances dissolved in it. The main components of this liquid, which cause an increase in specific gravity, are salts and urea, and in some pathological cases other substances (for example, glucose). Also, the density of urine determines the efficiency of the concentration work of the kidneys - their ability to secrete more concentrated urine. The normal density of urine is 1.012 – 1.022 g/ml.

This indicator can change slightly during the day, as well as under the influence of certain external factors (drinking regime, increased sweating).

• The specific gravity of urine and its disorders are determined relative to the density of blood plasma, which is 1.010 g/ml. In this case, three main pathological conditions are distinguished:
• Hyposthenuria – decrease in density less than 1.010 g/ml.
• Hypersthenuria – an increase in specific gravity over 1.025 g/ml.

Isosthenuria – urine density value at the level of 1.010 g/ml.

Why does the density of urine change?

• Hyposthenuria develops when more water is excreted in the urine. The reason for this is increased fluid consumption, reduction of extensive edema, during fasting and dystrophy. Also, a decrease in specific gravity can occur in case of kidney damage and endocrine disorders:
• In the third (polyuric) stage of renal failure, when the work of almost all processes of urine formation in the kidneys - filtration, secretion and reabsorption - is disrupted. In this case, against the background of hyposthenuria, there is a strong increase in daily diuresis (the amount of urine excreted).
• Acute interstitial nephritis.

Diabetes insipidus is an endocrine disease characterized by disruption of the hypothalamus and pituitary gland. In this case, there is a lack of the hormone vasopressin, which controls the absorption of water in the kidney tubules. In this situation, the density of urine drops to 1.004 g/ml and daily diuresis increases greatly (up to 10-15 liters per day).

Hypersthenuria indicates a significant concentration of various substances in the urine and can be observed in the form of two main clinical pictures:

• Increased specific gravity due to oliguria (small amount of urine excreted). This condition occurs when the kidneys are damaged, edema forms, or fluid loss occurs in other ways (excessive sweating, diarrhea).
• Hypersthenuria in combination with polyuria - increased diuresis. Almost the only reason for this phenomenon is diabetes mellitus - glucose and ketone bodies released in the urine greatly increase the density of this biological fluid.

Specific gravity(the second name is relative density) of urine is an indicator that characterizes the functioning of the kidneys and makes it possible to assess how well they cope with the function of filtering and removing unnecessary compounds from the body.

By studying the density of a biological fluid, a laboratory technician determines what content it contains:

• Creatinine.
• Urea.
• Uric acid.
• Sodium and potassium salts.

It is based on the values ​​of these parameters that the above criterion is calculated.

Specific gravity of urine: normal values ​​for men, women and children

Determination of urine density is carried out in a laboratory using a special device - urometer. In order for the data obtained to correspond to reality, the patient must correctly collect the material for the study (do not drink alcohol the day before, plenty of fluids).

Minor fluctuations in the parameter during the day are a normal physiological reaction. This is explained by changes that occur during eating, drinking water, performing heavy physical work, resting, increased sweating, etc. Under different conditions, the kidneys of a healthy person secrete urine, the density of which is normally equal to from 1.010 to 1.028.

In men and women who do not have diseases of the urinary system, with moderate physical activity, the specific gravity of morning urine is most often from 1.015 to 1.020. As for children, this figure may be slightly lower.

For children, the normal option is from 1.003 to 1.025. In the first week of life, the specific gravity of the child’s urine should be within the range up to 1.018, starting from the second week and until the end of the second year - from 1.002 to 1.004.

Later, the indicator begins to increase and, with normal kidney function, is already from 1.010 to 1.017. In children 4-5 years of age, the density is equal to 1,012-1,020 . For children over 10 years old, it should be in the range from 1.011 to 1.025.

Causes of decreased specific gravity of urine

If the density of biological fluid is below normal, they speak of hyposthenuria. This does not necessarily mean that the person is sick. Doctors know of cases where such a deviation was a consequence of the patient consuming an excessive amount of liquid shortly before taking a laboratory test.

The use of any diuretic drugs also leads to hyposthenuria. The doctor must be warned about this factor in advance so that the data obtained are not misinterpreted.

What diseases cause decreased specific gravity of urine?

If we talk about the pathological causes of hyposthenuria, they are as follows:

• Diabetes.
• Polydipsia (usually observed in people with mental instability)
• Neurogenic and nephrogenic diabetes insipidus.
• Inflammation of the renal tubules.
• The presence of unresolved infiltrates in the body.
• Untreated or complicated pyelonephritis.
• Chronic renal failure.
• Following an overly strict diet, lack of vitamins, trace elements and minerals in the diet.
• The presence of nodular formations on the renal tissues.
• Hormonal imbalance (typical for women of childbearing age, as well as during menopause).

Many patients with a significant decrease in the described indicator complain of:

• The appearance of edema on different parts of the body, limbs.
• Pain in the lower abdomen or lower back.
• Decrease/increase in the volume of urine excreted.

All these symptoms indicate problems with the kidneys, so if they appear, you should contact a qualified doctor as soon as possible and undergo an examination.

What to do if urine specific gravity is low

If the specific gravity of urine is much lower than normal, first of all it is necessary retake laboratory tests. It is imperative to take a responsible approach to the repeated collection of biological fluid; on the eve of diagnosis, do not drink too much fluid. If other indicators are normal, then most likely the person does not have any kidney disease.

If, in addition to low density, other deviations in laboratory tests are observed, a comprehensive examination is mandatory. What it will include must be decided by the therapist or urologist. Usually, patients are given directions to undergo a Zimnitsky test, which allows one to determine differences in urine density at different times of the day.

Specific gravity of urine during pregnancy

It is considered normal if the relative density of urine in the expectant mother is from 1.010 to 1.029.

Reducing the parameter is provided by:

• Excessive fluid intake.
• Edema.
• Hormonal surges.
• Kidney pathologies (nephropathy)
• Toxicosis.
• Frequent urination.

If, on the contrary, the criterion is elevated in a pregnant woman, the gynecologist may assume the presence of:

• Diabetes mellitus.
• Fluid deficiency, dehydration.
• Kidney inflammation.
• Severe toxicosis/gestosis.

The expectant mother should not worry if the test results are unsatisfactory. The analysis needs to be retaken soon. Only if re-diagnosis confirms the concerns that have arisen will the measures necessary to determine the cause of the condition be taken.

The specific gravity of urine is increased - causes and what to do

An increase in the specific gravity of urine is medically called hypersthenuria. Typically, this problem develops against the background of a decrease in the amount of separated biological fluid.

It can be provoked by:

• Severe vomiting, nausea.
• Insufficient fluid intake, dehydration.
• Injection of a radiopaque contrast agent into the patient’s body on the eve of a laboratory test.
• Proteinuria (presence of protein) in nephrotic syndrome.
• Diabetes.
• Taking large doses of antibacterial drugs.
• Inflammation of the genitourinary system.
• Toxicosis during pregnancy.

Hypersthenuria is characterized by symptoms such as:

• Discomfortable sensations in the abdominal area.
• Lower back pain.
• Edema formation for unknown reasons.
• A sharp decrease in single portions of urine excreted.
• Weakness, increased fatigue.

With hypersthenuria, as with hyposthenuria, the patient should undergo a Zimnitsky test to understand whether there are abnormalities in the functioning of the kidneys and to get a complete picture of their functioning.

The relative density of urine is an important diagnostic indicator, according to which the pathological conditions of the patient are determined. Depending on the disease and the stage of its progression, urine can have completely different relative densities, including reduced ones.

The relative density of urine is below normal - what might it indicate?

This test is carried out to determine the current functioning of the kidneys. These include Zimnitsky and Nechiporenko samples. The latter belong to the category of the most detailed laboratory studies, the results of which take into account the concentration of urea and salts. If these substances are contained in quantities that differ from the norm to a lesser extent, then the patient clearly has a reduced density of urine - hyposthenuria.

Since the specific gravity of urine is an integral part of the functional indicators of kidney function, it can be diagnosed if there is a suspicion of:

1. Kidney pathologies.
2. Inflammatory processes in other structures of the genitourinary system.
3. Somatic disorders.

Normal density values ​​in accordance with the mechanisms of urine formation

There are several stages of urine formation, after which the material necessary for analysis is formed.

At the first stage, the formation of urine of the primary composition occurs in the renal glomeruli. In this case, the blood, under the influence of internal renal pressure, is cleansed of toxins and other elements formed as a result of the past cycle.

In the second stage, the products separated from the blood go through the stages reabsorption through jade channels. Any useful substances that could be separated under pressure are returned to the body. The output is urine, which contains extremely harmful substances such as chlorine, sodium, various sulfates, and so on.

It is this obtained material that is used for analysis using a urometer.

Based on the results obtained, namely fixing the content of salts and urea, the value is determined. The latter cannot be called constant, since throughout the day, in the same biological material, the density can change several times. This depends on food, drinks, as well as banal fat loss through sweating.

Indicators are within normal limits according to the principle of age division

• baby, 1 day old - 1,008-1,018 (density according to urometer data);
• 6 months - 1,002-1,004 .
• from six months to 12 months – 1,006-1,016 .
• age from 1 to 5 years – 1,010-1,020 .
• from 6 to 8 years – 1,012-1,020 .
• from 9 to 12 – 1,012-1,025 .
• adult men and women - 1,010-1,025 .

It is worth noting that upon reaching the age of twelve, the density of the analyzed urine is completely comparable to that for the biological material of an adult.

Causes of decreased urine density

The study can show the presence of hyposthenuria only if the density is reduced to 1,005-1,010 . In this case, such indicators indicate a decrease in renal function, an integral part of which is antiarrhythmic hormones. If the amount of the latter increases, the fastest possible absorption of water in the body is provoked, resulting in a decrease in the concentration of urine.

Thus, the action works completely in the opposite direction, that is, in the absence or decrease in the amount of the mentioned hormones, urine concentrates too much, due to an increase in the amount of water. Given such a sharp increase in the amount of liquid being analyzed, its specific density decreases accordingly.

This is one of the most common reasons for the decline in the mentioned indicator, but, in fact, there are much more of them.

Decreased urine density in pregnant women

It is worth immediately noting that the normal indicator for a pregnant woman is 1.010-1.020. The causes of hyposthenuria during pregnancy may be:

• Any renal pathology.
• Hormonal imbalance.
• Urinating too frequently.
• Common toxicosis.

Urine density in newborns and children

At the time of birth, the indicator may radically deviate from the established norm. After some time, this indicator returns to normal. If a one-year-old child is diagnosed with hyposthenuria, then until the age of two there is absolutely no need to worry.

Otherwise, you should contact a specialist and undergo an examination.

Decreased urine density in adults

In the adult population, there are many more pathological reasons for the formation and progression of decreased urine density. These include:

1. Kidney failure, which has developed into a chronic disease.
2. Central diabetes.
3. Pyelonephritis.
4. Chronic nephritis.
5. The consequence of any inflammatory processes in the body due to the resorption of inflamed areas.
6. Nephrosclerosis.
7. Jade in intense form.
8. Dystrophy caused by starvation.
9. Glomerulonephritis.
10. Exposure to antibiotics or diuretics.

It is worth paying attention to the fact that a decrease in the specific density of urine can be caused by alcoholism or drug use.

What to do based on the diagnostic results?

If a decrease in the specific gravity of urine is caused by a natural factor, such as the consumption of a certain type of food and liquid, then there is no need to worry, but, on the contrary, exclude certain types of foods from the diet.

If the cause is one of the previously mentioned diseases, then you must immediately contact a specialist for advice and additional examinations. Through the latter, special medications are prescribed, during which a decrease in urine density can also be diagnosed.

One of the important indicators that is taken into account when analyzing data to make a diagnosis is the specific gravity of urine. In general, doctors need to conduct a general urine test to understand whether the organs and systems in the human body are working correctly. Few people know that in some serious diseases, symptoms do not manifest themselves for a long time; such a study will help to determine the cause of pathological processes in the early stages.

What is the role of urine specific gravity in the overall analysis?

Urine formation

Before understanding what changes in urine tests mean, you must first understand how urine formation and excretion from the body occurs. The process of producing urine consists of two stages. The procedure begins with the renal glomeruli, consisting of many capillaries, producing primary urine. At this stage, as a result of high pressure, the process of filtering blood, protein and other useful components from water and sugar occurs. After this, the fluid moves through the nephron tubules, where reabsorption occurs, which consists of the reverse absorption of urine and thereby the necessary substances are again in the body.

At the second stage, when useful components are separated from ammonia and other components, secondary urine is formed. The fluid continues its movement through the collecting ducts, kidneys, ureter and ends up in the bladder. After this, the process of removing fluid from the body naturally is completed.

How to determine the indicator?

Using a urometer, the density of biological fluid is determined.

In medicine, a special device is used to determine the density of urine - a urometer. To conduct the study, the material is poured into a special vessel and immersed in liquid. After this, the diagnosticians apply pressure and, after the container stops oscillating, record the value of the lower limit of the urine meniscus on the instrument grid. The result obtained characterizes the specific gravity of urine. To obtain an accurate result, it is important to consider the room temperature. Such caution is characterized by the fact that when the ambient temperature increases, the volume of liquid increases and, as a result, the concentration decreases.

Another popular tool for measuring the density of urine is strips to determine the concentration of various components in the urine. Low weight, as well as other indicators such as glucose, nitrites, protein are calculated using plastic or paper strips, divided into segments by color. Each test strip should be used only once, after which the instrument should be discarded. The data is compared with a color chart located on the back of the bottle.

The use of such strips allows you to get the result as quickly as possible and at home, but an accurate picture can only be obtained in the laboratory, after a complete study of the material by a specialist.

Normal indicators

A person’s diet can influence changes in urine values.

When the relative density of urine is normal, the kidneys carry out a full process of dilution and concentration of primary urine. The value of the indicator depends on the percentage of salts and urea in the liquid. Depending on diet, drinking regimen, and sweating, the values ​​may vary slightly over a short period. The relative density of urine is normal when a person does not have any pathologies of the urinary system, and problems with endocrine and psychological diseases are not recorded.

In a mature person

The norm for the specific gravity of urine in women and men is 1.015-1.025; in adults and children it differs for natural reasons, due to age, body weight, diet and lifestyle. When assessing the quality of urine, the following indicators are taken into account:

• The color of urine is rich shades of yellow, while the intensity is influenced by various factors: pathological processes in the body, uncontrolled use of medications, specific products that change urine to light pale and bright colors.
• Degree of transparency - in a healthy person, the urine is absolutely transparent. If mucus and other cloudy substances are found in the discharge, this may indicate infectious processes.
• Odor - if the patient notices the appearance of a characteristic odor of ammonia, it is recommended to use an analysis strip test and urgently seek advice from a specialist.

In a child and adolescent

Normal indicators in the analysis of a two-year-old child for an adult may indicate the presence of pathology.

High density urine changes with age. If in a child under one year of age the indicators are determined within the range of 1.016-1.018 and are considered the lowest indicator, then after a while it changes as they grow older. In an older child and a teenager, the values ​​remain at around 1.011 to 1.025 and the values ​​vary depending on the volume of fluid consumed per day. If the specific gravity of urine in children 2-4 years old is 1.025, this result means the norm, but for an adult this is the first serious symptom to begin a full examination, since the urine in this case is dense.

During pregnancy

From the moment a new life is born, a number of significant changes occur in a woman’s body; it adapts to work on 2 fronts, so it is logical to assume that the density of urine will change during this period. In addition to the fact that during pregnancy, a woman can be overtaken by toxicosis, which affects the functioning of the whole body, it can also cause hypersthenuria. Visually, urine can change in color: from a transparent yellowish liquid to a cloudy bright yellow.

Low specific gravity

People with kidney pathologies are more aware than anyone else of the problem of low urine density. The condition of the body in which the patient has a specific gravity of urine below normal is called hyposthenuria. The main problem lies in the fact that a person consumes more water, juices and liquids, which lead to increased kidney function. A striking example of this phenomenon are beer lovers who consume this alcoholic drink in crazy volumes. Such a destructive hobby significantly affects concentration and, as a result, the relative density of urine is reduced.

• drinking copious amounts of liquid - as a result of which water metabolism is compensated and the salts necessary for life are removed from the body along with urine;
• a decrease in indicators occurs with diabetes mellitus;
• inflammatory processes in the body;
• renal diseases: pyelonephritis, glomerulonephritis, various types of kidney failure;
• taking diuretic medications;
• reduced density is observed in women who abuse diets and whose diet is unbalanced.

Specific gravity is higher than normal

The indicator can increase when the need for water is reduced, as well as when there is significant fluid loss as a result of illness (stomach upset, vomiting, diarrhea). An increase in the specific gravity of urine is medically referred to as hypersthenuria. With high swelling of the extremities, similar processes are observed when the specific density increases sharply. Overestimated indicators are influenced by the following factors:

• high concentration of protein in urine;
• side effect of toxicosis during pregnancy;
• reaction to certain drugs;
• defects of the cardiovascular system.

A urine test is prescribed when examining for any disease, since it is a very informative diagnostic technique and can tell about the condition of many of the patient’s organs. Urine is evaluated according to various parameters - color, transparency, presence of impurities and other indicators. Of no small importance in diagnosis is the specific gravity of urine or its density, which can decrease or increase in various pathologies.

The density of urine is increased - what does this mean?

Increased relative gravity of urine can be detected with a traditional urinalysis and is caused by the amount of undissolved and dissolved substances contained in the urine. The more such components are present in urine, the higher its relative density. If a general laboratory test reveals that the specific gravity of urine is abnormal, the patient is prescribed additional diagnostic procedures.

Relative density is measured in various studies, the most famous of which is. Such a urine test, unlike a general one, allows for a fairly informative assessment of renal functionality (urinary excretion and concentration).

In essence, the Zimnitsky test is a diagnostic technique that measures the density of urine collected at certain hours. At the same time, a general urine test may indicate an increase in urine density.

Usually morning urine, which has accumulated overnight, is not examined. The collection of biomaterial for research begins with the second urination after waking up. Urine is collected every 3 hours, the first time at 9 am, in total 8 servings will be obtained per day, and each of them will be separately examined for the necessary indicators, in particular specific gravity or density. During the collection process, it is recommended to maintain the same diet, most importantly, write down the amount you drink.

Values

If during the research it turned out that the density is slightly higher than normal, that is, it rises above 1.035, then they talk about hypersthenuria. This is the name given to the phenomenon in which the specific gravity of urine exceeds the norm.

Normal indicators according to age:

1. Newborns in the first 10 days of life – 1.008-1.018;
2. At 2-3 years – 1.010-1.017;
3. 4-5 year olds – 1.012-1.020;
4. 10-12 year olds – 1.011-1.025;
5. In adults, the norm is considered to be urine density in the range of 1.010-1.025.

Fluctuations in daily urine output are considered normal. The morning portion, for example, will be more excessive, because the patient usually does not drink anything at night, so the urine is not diluted with anything. The specific gravity of urine during the daytime has the lowest density and is excreted in the largest volumes.

Causes

There are several factors leading to a relative increase in the specific gravity of urine. They may differ slightly in pregnant women, adult patients and children. The causes of deviations can be pathological or physiological. Pathological factors for detecting high urine density are associated with certain diseases, while physiological ones can be caused by temporary factors such as heavy sweating, drinking large amounts of liquid during the day, etc.

In pregnant women

In pregnant women, due to their condition, traditional toxicosis occurs, which is the main reason for the increase in urine density. In addition, some patients experience fluid retention in the body, which doctors associate with gestosis. This factor also provokes the development of hypersthenuria in pregnant women.

In children

In a child, an increase in specific gravity is often associated with kidney diseases and changes in organ tissues. In addition, children often have intestinal infections or poisonings that cause vomiting or diarrhea. These manifestations cause severe dehydration of the body and lead to high urine density.

The specific gravity indicator may be increased in the first days of a newborn’s life, but doctors say that this deviation is often only physiological in nature and after several days it returns to normal on its own.

In adults

Hypersthenuria usually occurs due to factors such as:

• The presence of protein in urine or proteinuria;
• Increased glucose levels, typical for diabetics. Experts also call this condition glucosuria;
• The presence of kidney problems such as kidney failure, glomerulonephritis, infectious pathologies such as cystitis or nephritis;
• Taking a large number of drugs that are actively excreted in the urine, for example, diuretics or antibiotics;
• Fluid deficiency, when a person drinks a small amount of water per day;
• Acute organic dehydration associated with profuse sweating, diarrhea or uncontrollable vomiting.

In general, the reasons why urine density is higher than normal are approximately the same in all segments of the population. To determine the true causes of such disorders, it is recommended to undergo a Zimnitsky test, which will allow a detailed study of renal activity and obtain a more complete picture of their functionality.