Decreased specific gravity of urine causes. The main causes of nephrogenic diabetes insipidus. Specific gravity above normal
They can fluctuate within fairly wide limits, and these fluctuations can be physiological or pathological. Physiological fluctuations are a variant of the norm, and pathological fluctuations reflect a disease.
An increase or decrease relative to the norm of any indicator cannot be assessed unambiguously, and it is impossible to draw a conclusion about the presence of a disease. The results of the analyzes can help to find out the possible cause of the disorders, which can only be at the stage of the syndrome, and not the formed disease. Therefore, timely detection of deviations in the analyzes will help to start treatment and prevent the progression of the disease. Also, test results can be used to monitor the effectiveness of treatment.
Consider the probable causes of changes in various indicators of the general analysis of urine.
Reasons for changing the color of urine
In the presence of pathology, urine can change its color, which indicates a certain syndrome and disease.The correspondence of urine colors to various pathological conditions of the body is reflected in the table:
| pathological color urine | Possible disease (cause of discoloration of urine) |
| Brown, black |
|
| Red (color of meat slop) |
|
| Dark brown frothy (urine color beer) |
|
| Orange, rose red |
|
| Brown (color of strong tea) |
|
| Colorless or white-yellow |
|
| Dairy (color of milk, cream) |
|
These color variations will help guide you, but other examinations and clinical symptoms should be taken into account to make an accurate diagnosis.
Causes of turbidity in the urine
Violation of the transparency of urine is the appearance of turbidity of varying severity. Turbidity in the urine can be represented by a large amount of salts, epithelial cells, pus, bacterial agents, or mucus. The degree of turbidity depends on the concentration of the above impurities.From time to time, every person has cloudy urine, which is formed by salts. If you are unable to pass this urine to analysis to the laboratory, then you can conduct a test to determine the nature of the turbidity.
To distinguish salts in urine from other variants of turbidity at home, you can slightly warm the liquid. If the turbidity is formed by salts, then it can either increase or decrease until it disappears. Turbidity, formed by epithelial cells, pus, bacterial agents or mucus, does not change its concentration at all when urine is heated.
Causes of change in the smell of urine
The smell of fresh urine is normal - not sharp and not irritating.Most often, the following pathological odors of urine are noted:
1.
The smell of ammonia in the urine is characteristic of the development of inflammation of the mucous membrane of the urinary tract (cystitis, pyelitis, nephritis).
2.
The smell of fruits (apples) in the urine develops in the presence of ketone bodies in people with type 1 or type 2 diabetes.
Causes of changes in the acidity of urine
The acidity of urine (pH) can change into an alkaline and into an acidic region, depending on the type of pathological process.The reasons for the formation of acidic and alkaline urine are shown in the table:
Causes of changes in the density of urine
The relative density of urine depends on the function of the kidneys, therefore, a violation of this indicator develops with various diseases of this organ.Today, the following options for changing the density of urine are distinguished:
1.
Hyperstenuria - urine with a high density, more than 1030-1035.
2.
Hypostenuria - urine with a low density, in the range of 1007-1015.
3.
Isosthenuria - low density of primary urine, 1010 or less.
A single discharge of urine with high or low density does not give grounds for identifying the syndrome of hypostenuria or hyperstenuria. These syndromes are characterized by prolonged excretion of urine during the day and at night, with high or low density.
Pathological conditions that cause violations of the density of urine are reflected in the table:
| Hyperstenuria | Hypostenuria | Isosthenuria |
| Diabetes mellitus type 1 or 2 (the density of urine can reach 1040 and above) | diabetes insipidus | Chronic renal severe insufficiency degree |
| Acute glomerulonephritis | Resorption of edema and inflammation infiltrates (the period after the inflammatory process) | Subacute and chronic jade severe |
| congestive kidney | Nutritional dystrophy (partial starvation, nutritional deficiencies, etc.) | Nephrosclerosis |
| nephrotic syndrome | Chronic pyelonephritis | |
| Edema formation | chronic nephritis | |
| Convergence of edema | Chronic renal failure | |
| Diarrhea | Nephrosclerosis (degeneration of the kidney tissue into connective) | |
| Glomerulonephritis | ||
| Interstitial nephritis |
Determination of chemicals in urine for various diseases
As we can see, the physical properties of urine in the presence of any diseases can change quite significantly. In addition to changes in physical properties, various chemicals appear in the urine that are normally absent or present in trace amounts. Consider, in which diseases there is an increase in concentration, or the appearance in the urine of the following substances: - protein;
- bile acids (pigments);
- indican;
- ketone bodies.
Causes of protein in the urine (proteinuria)
The appearance of protein in the urine can be caused by various reasons, which are classified into several groups, depending on the origin. An abnormal increase in the concentration of protein in the urine above 0.03 g is called proteinuria. Depending on the protein concentration, moderate, moderate and severe degrees of proteinuria are distinguished. Moderate proteinuria is characterized by a loss of protein up to 1 g/day, medium - 1-3 g/day, severe - more than 3 g/day.Types of proteinuria
Depending on the origin, the following types of proteinuria are distinguished:- renal (kidney);
- congestive;
- toxic;
- feverish;
- extrarenal (extrarenal);
- neurogenic.
| Type of proteinuria | Reasons for the development of proteinuria |
| Renal (kidney) |
|
| stagnant |
|
| toxic | Use of the following medications at very high doses: salicylates, isoniazid, painkillers, and gold compounds |
| feverish | A severe increase in body temperature caused by any disease |
| Extrarenal (extrarenal) |
|
| neurogenic |
|
Causes of glucose (sugar) in the urine
The presence of glucose in the urine is called glucosuria. The most common cause of glucosuria is diabetes mellitus, but there are other pathologies that lead to this symptom. So, glycosuria is divided into the following types:
1.
Pancreatic.
2.
Renal.
3.
Hepatic.
4.
Symptomatic.
Pancreatic glucosuria develops against the background of diabetes mellitus. Renal glucosuria is a reflection of the pathology of metabolism, and occurs from an early age. Hepatic glucosuria can develop with hepatitis, traumatic organ damage, or as a result of poisoning with toxic substances.
Symptomatic glucosuria is caused by the following pathological conditions:
- concussions;
- hyperthyroidism (increased concentration of thyroid hormones in the blood);
- acromegaly;
- Itsenko-Cushing's syndrome;
- pheochromocytoma (tumor of the adrenal glands).
Causes of bilirubin in urine
Bilirubin in the urine appears with parenchymal or obstructive jaundice. Parenchymal jaundice includes acute hepatitis and cirrhosis. Obstructive jaundice includes various types of blockage of the bile ducts with an obstruction to the normal outflow of bile (for example, cholelithiasis, calculous cholecystitis).Reasons for the appearance of urobilinogen in the urine
Urobilinogen at a concentration exceeding 10 µmol / day is determined in the urine with the following pathologies:- infectious hepatitis;
- chronic hepatitis;
- cirrhosis of the liver ;
- tumors or metastases to the liver;
- hemoglobinuria (hemoglobin or blood in the urine);
- hemolytic jaundice (hemolytic disease of the newborn, hemolytic anemia);
- infectious diseases (malaria, scarlet fever);
- fever of any cause;
- the process of resorption of foci of hemorrhage;
- volvulus;
- bile acids (pigments);
- indican.
Causes of Bile Acids and Indican in Urine
Bile acids (pigments) appear in the urine with an increase in the concentration of direct bilirubin in the blood above 17-34 mmol / l.Causes of bile acids in urine:
- Botkin's disease;
- hepatitis;
- obstructive jaundice (calculous cholecystitis, cholelithiasis);
- cirrhosis of the liver.
Causes of ketone bodies in urine
Ketone bodies include acetone, hydroxybutyric acid, and acetoacetic acid.Reasons for the appearance of ketone bodies in the urine:
- diabetes mellitus of moderate and high severity;
- fever;
- severe vomiting;
- therapy with large doses of insulin for a long period of time;
- eclampsia of pregnant women;
- hemorrhage in the brain;
- traumatic brain injury;
- poisoning with lead, carbon monoxide, atropine, etc.
Deciphering the microscopy of the urinary sediment
One of the most informative fragments of a general urine test is sediment microscopy, in which the number of different elements in one field of view is counted.Leukocytes, pus in the urine - possible causes of the appearance
An increase in the number of leukocytes more than 5 in the field of view indicates a pathological process of an inflammatory nature. An excess of white blood cells is called pyuria - pus in the urine. Reasons for the appearance of leukocytes in the urine:
- acute pyelonephritis;
- acute pyelitis;
- acute pyelocystitis;
- acute glomerulonephritis;
- treatment with aspirin, ampicillin;
- heroin use.
Sometimes, urine is stained to clarify the diagnosis: the presence of neutrophilic leukocytes is typical for pyelonephritis, and lymphocytes for glomerulonephritis.
Erythrocytes, blood in the urine - possible causes of the appearance
Erythrocytes in the urine can be present in various quantities, and at their high concentration they speak of blood in the urine. By the number of erythrocytes in the urinary sediment, one can judge the development of the disease and the effectiveness of the treatment used.Reasons for the appearance of red blood cells in the urine:
- glomerulonephritis (acute and chronic);
- pyelitis;
- pyelocystitis;
- chronic renal failure;
- injury (bruise, rupture) of the kidneys, urethra or bladder;
- tuberculosis of the kidney and urinary tract;
- tumors;
- taking certain medications (sulfa drugs, urotropin, anticoagulants).
Cylinders in the urine - possible causes of the appearance
Among all types of cylinders, the appearance of hyaline is most often noted in the urinary sediment. All other types of cylinders (granular, waxy, epithelial, etc.) appear much less frequently.The reasons for the detection of various types of cylinders in the urine are presented in the table:
| Type of cylinders urinary sediment | Causes of the appearance of cylinders in the urine |
| hyaline |
|
| grainy |
|
| waxy |
|
| Erythrocyte |
|
| epithelial |
|
Epithelial cells in the urine - possible causes of the appearance
Epithelial cells are not just counted, but also divided into three types - squamous epithelium, transitional and renal.Squamous epithelial cells in the urinary sediment are detected in various inflammatory pathologies of the urethra - urethritis. In women, a small increase in squamous cells in the urine may not be a sign of pathology. The appearance of squamous epithelial cells in the urine of men no doubt indicates the presence of urethritis.
Transitional epithelial cells in the urinary sediment are detected with cystitis, pyelitis, or pyelonephritis. The hallmarks of pyelonephritis in this situation is the appearance of transitional epithelial cells in the urine, in combination with protein and a shift in the reaction to the acid side.
Cells of the renal epithelium appear in the urine with a serious and deep lesion of the organ. So, most often, renal epithelial cells are detected with nephritis, amyloid or lipoid nephrosis, or poisoning.
Pathologies leading to the release of salts into the urine
Crystals of various salts may appear in the urine and are normal, for example, due to dietary characteristics. However, in some diseases, the excretion of salts in the urine is also noted.Various diseases that cause the appearance of salts in the urine are presented in the table:
The table shows the most common salts that have diagnostic value.
Mucus and bacteria in the urine are possible causes
Mucus in the urine is determined with urolithiasis or long-term chronic inflammation of the urinary tract (cystitis, urethritis, etc.). In men, mucus may appear in the urine with prostatic hyperplasia. The appearance of bacteria in the urine is called bacteriuria. It is caused by an acute infectious and inflammatory process occurring in the organs of the urinary system (for example, pyelonephritis, cystitis, urethritis, etc.).
A general urinalysis provides a sufficiently large amount of information that can be used to make an accurate diagnosis in combination with other methods. However, remember that even the most accurate analysis does not allow diagnosing any disease, since this requires taking into account clinical symptoms and objective examination data.
To date, any diagnosis involves a number of laboratory tests. The general analysis of urine and blood is carried out most often. An informative indicator in OAM is the relative density of urine (SG), which allows you to identify impaired renal function (hyper-, hypostenuria, isosthenuria).
Normal Relative Density
The concentration ability of each kidney is determined by the specific gravity of urine, the norm of which is determined in the general analysis. Urine excreted from our body is considered secondary. At the first stage of filtration, the blood, passing through the glomerular structures, separates large components. This is primary urine, which differs from blood in the absence of proteins and blood cells. In the final sections of the filtration apparatus, a larger amount of water is absorbed along with the ions necessary for the body. As a result, only 2 liters of secondary urine are filtered per day, while the primary is about 70 liters.
The less water a person drinks during the day, the more concentrated his urine becomes. An increase in the density of urine is reflected in the interpretation of the analysis as hyperstenuria. Conversely, with an excess amount of water drunk, a decrease in urine density is observed, referred to as hypostenuria. At the same time, the average daily volume of excreted biological fluid also changes.
The norm of the specific gravity of urine in adults according to the urometer should not go beyond the range of 1.015-1.025. The body of a child differs from an adult in incomplete processes of formation and adaptation. Therefore, the specific gravity of urine in children is different and depends on their age. An infant up to a year has a rather low density of urine, it is 1.010. The older the child, the higher the level of density can be determined. This depends on the ability of the distal tubules to reabsorb water and chemicals.
The study of the concentration of dry urine residue
The process of determining the specific gravity of urine is simple, but it requires special equipment. The relative density of urine is determined by a special device - a urometer at a temperature of 15 ° C and in the analysis has the designation SG. In clinical laboratories, as a rule, universal urometers are used. By analyzing urine, specific gravity can be determined within a division scale from 1.000 to 1.050. The specific gravity of urine corresponds to the position of the lower meniscus on the scale of the urometer. The physiological reasons for changes in the density of urine are different:
- temperature fluctuations in the external environment;
- evaporation of water during the act of breathing;
- food irritants (spicy, salty, fatty and fried foods);
- water imbalance.
Vegetative dominance at night slows down breathing and sweating. There is no water factor at night, which is why it is most informative to take OAM in the morning.
The concentration of urine in women is more prone to various changes and requires more attention. Evaluation of the filtration and concentration functions of the kidneys involves a whole range of tests. Physiological change in the level of specific gravity of urine is cyclical to the daily rhythm. Therefore, for a complete picture, it is necessary to carry out monitoring throughout the day.
The Zimnitsky test can be carried out in a child, as well as in men and women. Such a study is most often carried out in hospitals, since the analysis is collected at 8 time intervals in different containers. The amount of fluid consumed should not be artificially increased, otherwise the result will not be accurate. The volume of each sample is determined, the specific gravity of the test material in each portion (collected in 3 hours) is determined by the urometer. Normal diuresis per night should not exceed 20 - 35% of the daytime. If the amount of nocturnal diuresis increases, a condition called nocturia occurs. It indicates renal or postrenal disorders.
Increased urine density is recorded at a specific gravity of more than 1030 and indicates excessive water reabsorption. Hypostenuria characterizes a decrease in the specific gravity of urine to 1002-1012. Hypoisostenuria is diagnosed when the density drops below the norm (1010) for a whole day with a fluctuation of no more than 10. The kidneys lose their concentration ability.
The concentration test is carried out with the complete exclusion of liquid, the intake of protein products is allowed. Urine is collected every 4 hours in different containers. The interpretation of the results is similar to the Zimnitsky test. It is important that all the rules for collecting and examining urine are followed, and that the urometer is in good working order.
Increased specific gravity of urine
The specific gravity of urine is increased in diseases of various systems of the human body. Hyperstenuria is characterized by severe swelling of various parts of the body. Density above the norm is determined under the following conditions:
- fluid loss not with urine (sweat, vomiting, diarrhea, bleeding, massive burns);
- large doses of nephrotoxic antibiotics;
- injuries of the digestive tract;
- small or large intestine obstruction;
- diseases of the excretory system;
- endocrine disorders with metabolic disorders.
Most often, the concentration of dry residue exceeds normal values in renal failure, glomerulonephritis or pyelonephritis. Also, the density of urine is increased with endocrine pathologies. The hormones vasopressin and aldosterone have a major effect on fluid retention in the body. Thus, due to the increase in the concentration of dry residue, a high urine density is formed.
When the relative density of urine shows an excess of permissible values, a non-specific clinical picture can be noted:
- decrease in the amount of excreted urine to oliguria;
- darkening of its shade;
- unpleasant specific aroma;
- swelling;
- pronounced astheno-vegetative syndrome;
- pain in the abdomen or lumbar region.
The density of urine in children, the norm of which is always less than in adults, can sometimes increase. The highest fluid loss for a baby during intestinal infections makes urine more concentrated, creating a lot of adverse effects. All unnecessary metabolic products do not have time to be removed from the child's body, leading to intoxication of the fragile organism. This is especially pronounced in infants, since the work of most of their systems is not yet perfect.
Often infectious and gastrointestinal diseases require plentiful drinking. Water supplies are replenished with a surplus. Gradually, the amount of dry residue in OAM becomes small. The low specific gravity of urine is normalized only after the full recovery of the body. This condition is considered physiological and does not require drug correction.
Reduced specific gravity can be detected with polydipsia. This is a state characterized by constant thirst. To satisfy it, patients drink an amount of water that is several times higher than the norm. As a result, the excreted metabolic product is not concentrated and in large quantities. Unfortunately, this disease often manifests itself in mentally unstable people.
Neurogenic diabetes insipidus is characterized by thirst and frequent urination. Such diabetes often develops with craniocerebral injuries, infectious lesions, tumor processes, intracranial surgical interventions. The hypothalamus synthesizes an insufficient amount of the hormone vasopressin, and it cannot fully perform its functions. The fluid is irretrievably excreted, and even compensation with water intake does not save, since vasopressin is still not enough to maintain water reabsorption at the desired level.
In situations where the hormone is produced in sufficient quantities, and urine is still excessively excreted, there may be a loss of receptors sensitive to vasopressin by the kidney. Nephrotoxic drugs, polycystic disease, chronic renal failure, urolithiasis, and congenital renal anomalies are only a small part of the causes of neurogenic diabetes insipidus. The absence of predisposing factors for diabetes forces the diagnosis of an idiopathic disease.
Density in the analysis of urine below the norm is also observed in chronic glomerulonephritis, amyloidosis of the kidney, acute pyelonephritis. But the most common pathologies with reduced urine density are in diabetes mellitus (nephrogenic and neurogenic etiology).
In the differential diagnosis of diabetes mellitus, the determination of glucose and protein, which are often elevated, will be very useful.
Changes in the relative density of urine in pregnant women
During pregnancy, the indicator of the concentration ability of the kidneys can both increase and decrease. Since dehydration in expectant mothers mainly occurs with toxicosis, it is this condition that more often than others increases the specific gravity of urine.
If the specific gravity of urine is lowered for pathological reasons, then this should be taken seriously. Such diseases include diabetes insipidus in pregnant women and in patients with nervous disorders. Urine analysis during pregnancy may differ in a small specific gravity, what does this mean? There may be several reasons. Firstly, this is a decrease in renal functionality due to a pressing uterus and an increase in load. Secondly, hormonal changes significantly affect all levels of regulation, which also affects the urinary system. These factors tend to reduce the density by increasing the excretion of fluid in pregnant women from the body.
Many of the conditions discussed are very serious and require special attention. It is necessary to monitor the condition of your kidneys in order to prevent adverse and even dangerous complications.
The specific gravity of urine in the norm indicates a good condition, primarily of the kidneys. Deviation of the concentration ability from the norm, especially persistent, requires a number of additional examinations, consultation with a competent nephrologist and the appointment of the necessary treatment. It is worth taking care of your health and taking tests more often, because timely identified violations are always easier to eliminate.
At the moment, all examinations of the state of human health are accompanied by the delivery of laboratory tests. The most common and informative is urinalysis, the results of which can be used to judge not only the presence of pathologies of the urinary system, but also other diseases in the body. An important indicator of the analysis is the relative density of urine, which allows to evaluate the functional activity of the kidneys, their ability to accumulate, filter and excrete urine.
The deviation of the specific gravity of urine from the norm helps to identify pathologies at their initial stage and immediately begin drug therapy.
What is laboratory analysis based on?
The specific gravity of urine is an indicator that characterizes the ability of the kidneys to increase or decrease the concentration of urine. Biological fluid is formed in the kidneys in several stages. First, under the pressure of blood in the glomerular capillaries, the components of the blood are filtered through their walls. Its composition is close to that of blood plasma. But there are also differences: the molecules of proteins, fats and glycogen are too large and are not able to penetrate through the vascular walls into the glomeruli of the capsule.
Moving along the tubule of the nephron, primary urine (about 160 liters per day) is reabsorbed into the renal tubules. There is a process of reabsorption of nutrients into the bloodstream. Residual fluid with the breakdown products of proteins, fats and carbohydrates contained in it form secondary urine, which is excreted during urination. This dry residue is represented by:
- urea;
- salts of uric acid;
- sulfates;
- chlorides;
- ammonia ions.
It does not matter what total volume of fluid enters the body per day - the structural elements of the kidneys remove all metabolic products. If a person drank a small amount of water, then his urine will be saturated with mineral compounds. This means that the specific gravity of the urine is increased, and the patient has hyperstenuria.
With an increased content of fluid in the body in the secondary urine, the concentration of dry residue is relatively low. With each urination, not only metabolic products are excreted, but also excess fluid. Thus, there is a formation of low concentrated urine with a low specific gravity of urine - hypostenuria.
Determining the specific gravity of urine is an important part of laboratory tests.
Determination of specific gravity of urine
Urine analysis to determine the specific gravity is carried out using a special urometer device, or hydrometer. Carefully, along the wall, urine is poured into the cylinder. If a small amount of foam has formed, then it should be removed by blotting with filter paper. The device with urine is immersed in the liquid, while the laboratory assistant makes a small effort to eliminate vibrations. The relative density of urine is determined by the level of the lower meniscus of the hydrometer scale. The walls of the cylinder should not be in contact with the urometer, so its diameter is smaller than the diameter of the cylinder.
For some diseases of the urinary system (for example,) urine is taken from the patient using a catheter. The resulting volume is measured in a few drops, and it is diluted with distilled water, and after determining the relative density of urine, the degree of dilution is taken into account in the calculations.
If there is very little urine taken for analysis, then both qualitative and quantitative parameters are used in the studies:
- A balanced mixture of benzene and chloroform is placed in the cylinder.
- Add a drop of urine.
- With hypostenuria, the sample is distributed over the surface of the mixture, with hyperstenuria, it will sink to the bottom of the vessel.
- By adding benzene or chloroform in parts, the sample is ensured to be exactly in the middle of the liquid level.
- The relative density of urine will be equal to the specific gravity of the solution determined by the urometer.
All hydrometers are calibrated at 15°C. Therefore, when calculating, a correction is made for the ambient temperature. When it rises, a person's need for fluid intake increases significantly, and when it decreases, they decrease. This affects both the average daily volume of urine excreted and its relative density.
Using a urometer, the specific gravity of urine is determined
Normal specific gravity
The specific gravity index characterizes the functional activity of the kidneys by dilution or concentration of urine. It directly depends on the needs of the human body, the saturation of secondary urine with metabolic products, and the ambient temperature. The relative density of urine is a variable value, changing an arbitrary number of times per day. These changes are driven by the following factors:
- the use of spicy, salty, fatty, fried foods;
- increase or decrease in the amount of fluid you drink;
- profuse sweating due to illness or when the ambient temperature rises;
- release of fluid during respiration.
The relative density of urine should normally vary between 1.015-1.025 in an adult healthy person. The specific gravity of urine in children differs from adult rates and depends on the age of the child. In analyzes taken immediately after the birth of the baby, the lowest relative density of urine is recorded - about 1,010. As the child grows, the specific gravity of urine also gradually increases.
The specific gravity of morning urine is normal for men and women is about 1.02. As a rule, this is the highest indicator of dry residue content in urine per day.
At night, a person's breathing is slowed down, sweating is reduced, and there is no replenishment of the fluid level. Therefore, for testing, such urine is the most informative sample.
Relative density above normal
Increased urine density occurs when certain pathological processes are present in the human body. Hyperstenuria is manifested by increasing swelling, especially often such a symptom causes glomerulonephritis or chronic renal failure. With various diseases of the endocrine system, the specific gravity of urine increases significantly. There is a certain relationship between the violation of the production of hormones and a decrease in the fluid content in the human body.
Hyperstenuria can appear in men and women for the following reasons:
- With significant fluid loss as a result of vomiting, prolonged diarrhea, blood loss, extensive burns.
- With abdominal trauma and intestinal obstruction.
- With toxicosis in pregnant women.
- Diseases of the urinary system in acute or chronic form.
- The use of antibiotics in high doses.
There are many factors that lead to an increase in the relative density of the solids in the urine. Specialists distinguish between pathological and physiological causes of hyperstenuria. Pathological factors include endocrine diseases that occur with metabolic disorders, as well as diseases of the genitourinary system. Physiological causes are quite natural, do not require medical intervention. These include profuse sweating, thirst after eating salty or spicy foods.
Despite the fact that the causes of increased are very different, there are common symptoms of hyperstenuria:
- decrease in the volume of urine released with each urination;
- changing the color of urine to darker;
- the appearance of an unpleasant specific odor;
- the occurrence of edema of various localization;
- increased weakness, fatigue, drowsiness;
- pain in the abdomen and (or) lower back.
In young children, high urine density is often associated with the presence of congenital or acquired diseases of the urinary system. Also, babies are prone to the appearance of intestinal and gastric infections due to high vascular permeability and immunity that has not yet been fully formed. In case of poisoning, fluid loss occurs as a result of vomiting and diarrhea, which leads to hyperstenuria.
The clinical picture of diabetes mellitus is characterized by an increase in the glucose content in urine. The relative density will be higher if an excess concentration of proteins and their breakdown products is found in the urine. To identify the true cause of such a violation, several tests are required, with the help of which the doctor will evaluate the functional activity of the kidneys.
The specific gravity of urine can be determined at home using test strips.
Specific gravity below normal
After suffering infectious pathologies or diseases of the gastrointestinal tract, doctors recommend that the patient increase the volume of water consumed to replenish the body's fluid supply. This leads to hypostenuria - a change in the relative density of urine below normal. This factor in reducing the concentration of dry residue in urine is considered normal, physiological, as well as drinking plenty of water in hot weather, as well as after taking herbal or medicinal diuretics.
Pathological causes of hypostenuria include:
- Neurogenic diabetes insipidus, in which the synthesis of vasopressin is disrupted or its secretion by the pituitary gland (an appendage of the brain) is reduced. Patients without treatment are diagnosed with permanent dehydration.
- Nephrogenic diabetes insipidus. Violations occur at the level of cells of the distal nephron tubules, which do not respond to antidiuretic hormone.
- Diabetes insipidus of pregnant women, disappearing after the birth of the child.
- Nervous diabetes insipidus. It develops against the background of stressful situations or prolonged depression.
- Chronic diseases of the urinary system, in which there is a violation of the processes of filtration and excretion of urine.
- An acute inflammatory process that affects the tubules of the kidneys is pyelonephritis.
The norm of the specific gravity of urine is 1.015, if the indicator falls below, then the doctors ascertain hypostenuria. This condition requires further careful diagnosis to identify the cause of the decrease in the functional activity of the kidneys, their ability to concentrate the dry residue.
This process is directly dependent on the production of vasopressin, an antidiuretic hormone that regulates the reabsorption of fluids in the structural elements of the kidney. The absence of vasopressin or a decrease in its concentration provokes the formation of increased volumes of urine with a low density.
You can read more about the causes of low specific gravity of urine.
Functional trials
To assess the functional state of the kidney, one laboratory analysis of urine is not enough. The relative density can change throughout the day, therefore, to more accurately determine the ability of the kidneys to accumulate compounds, functional tests are carried out. Some evaluate the ability of the urinary system to concentrate urea and its salts, while others - to allocate them from the human body.
Zimnitsky's test
The analysis evaluates the functional activity of the kidneys in women and men without changes in the drinking regimen. A person urinates every three hours, collecting eight urine samples by the end of the day. Using a urometer, the relative density of urine and the resulting volume are determined. The resulting result shows a normal difference between diuresis at different times of the day: the night should be approximately 30% of the daytime.
concentration test
The study is based on a change in the patient's diet: the use of any liquid is completely excluded from it for a day. To prevent hunger, protein foods are allowed. Some patients find it difficult to tolerate such a diet, and they are allowed to drink a few sips of water. Urine is collected every four hours so that doctors can evaluate its relative density and physical parameters. If the indicators fluctuate between 1.015-1.017, then the kidneys are not coping with their function of concentrating urine. A decrease in readings to 1.01 indicates the development of isosthenuria, a condition in which the kidneys lose their ability to concentrate urine.
If a person regularly takes laboratory tests, including to determine the relative density of urine, this means that he takes care of his health. The sooner a violation in the work of the kidneys is detected, the higher the likelihood of a complete cure.
The relative density of urine is considered a rather important diagnostic indicator, especially in nephrology. In certain pathological conditions, the specific gravity of urine is increased or decreased.
Low urine density - what does it mean?
Sometimes, to determine the degree of performance of the renal structures, it becomes necessary to conduct such specific studies as the Zimnitsky, Nechiporenko test, etc. It is during a laboratory study of urine that hypostenuria or reduced urine density is detected, which is determined by the concentration of substances present in it (urea and various salts) .
Usually, such a detailed study of urine is prescribed for suspected pathologies of the kidneys or other structures of the genitourinary system. Yes, and with somatic disorders, urine tests are indispensable, because the specific gravity of urine is one of the main functional indicators of renal activity.
In addition, the determination of this value helps to reveal the filtration capacity of the kidneys. Why is that? The point is the mechanisms of urine formation.
Urine is formed in several stages:
- First, primary urine is formed in the renal glomeruli. Under pressure, the blood is filtered, cleared of various toxins and other waste products.
- Then the primary biomaterial is reabsorbed through the nephron tubules, and useful substances from it are returned to the body again, while the remaining liquid, containing ammonia impurities and urea, uric acid components and sulfates, chlorine and sodium, forms urine of the secondary type. It is sent to the bladder structures, from where it is then brought out.
The determination of the specific gravity of urine is carried out using a special device - a hydrometer (or urometer). The development of hypostenuria is said to be if in all portions of urine during the Zimnitsky test, the specific gravity is below 1.010.
Values
The value of urinary density is determined by the content of salts and urea in it. As a rule, this indicator is not constant and throughout the day it constantly changes, which depends on the food and drink consumed, on the loss of fluid through sweat, etc.
- For adults, the norm is 1.015-1.025.
- In newborns, these values are 1.002-1.020.
- In the future, the level of urine density gradually increases and by the age of 5 it normally reaches 1.012-1.020;
- Starting from the age of 12, this figure is the same as that of an adult, i.e. 1.011-1.025.
So, the following indicators are considered normal:
The reasons
Decreased urine gravity, or hypostenuria, is diagnosed when the urinary density falls to 1.005-1.010. Such a decrease may indicate a low concentration of renal function, which is regulated by antidiuretic hormonal substances. If such hormones are present in abundance, then water in the body is absorbed much more actively, so urine is concentrated little. If there is no antidiuretic hormone or there is too little of it, then a lot of urine is formed, and its specific gravity decreases. There are many reasons for reducing the share.
In pregnant women
In women in a normal position, the specific gravity of urine is 1.010-1.025.
Hypostenuria in pregnant women is usually detected due to:
- renal pathologies;
- Hormonal disorders;
- With excessive urination;
- With toxicosis of pregnant women.
In children
In newborns, a decrease in the proportion is usually recorded immediately after birth, but soon all indicators return to normal. On average, for newborns in the first weeks of life, the characteristic maximum density values are 1.016-1.018. Relative hypostenuria is considered the norm even in a healthy child in the first year of life.
If the relative density of urine is lowered for a longer period, then they speak of disorders in the renal activity associated with organ failure.
In adults
In the adult population, pathological causes of low urine density are caused by conditions such as:
- Chronic kidney failure;
- Diabetes insipidus type (nephrogenic, central or idiopathic);
- Chronic pyelonephritis;
- Chronic nephritis;
- Resorption of edematous zones and infiltrates of inflammatory origin, which is usually observed during the recovery period after any inflammation;
- The degeneration of healthy kidney cells into connective tissue structures, characteristic of nephrosclerosis;
- Nutritional dystrophy due to lack of nutrients and starvation;
- Glomerulonephritis;
- Acute tubular lesions;
- Lack of antidiuretic pituitary hormone, in which there is no proper absorption of water, resulting in dilute urine with low density;
- Involuntary polydipsia, characteristic of persons prone to various kinds of neurotic disorders and having an unstable psyche (mainly in women);
- Abundant drinking regimen or taking diuretic drugs, etc.
The physiological decrease in the specific gravity of urine occurs against the background of alcohol abuse, but soon, if the patient stops drinking, the indicators return to normal.
In parallel with a decrease in density, patients may observe signs of kidney failure such as:
- Hyperedema all over the body;
- chronic fatigue;
- Pain in the area of the lower abdomen and lumbar;
- Changes in the color characteristics of urine (darkening or the appearance of bloody impurities);
- Decreased total urine output.
If the reason that the density of urine is below normal is diabetes, when blood sugar increases, then patients involuntarily begin to drink more fluids and urinate more often.
Regardless of the reasons that provoked the density of urine less than normal, the appearance of pathological signs requires a medical examination. Each of the factors, if left untreated, can cause complications, therefore, it needs mandatory treatment.
Specific gravity is one of the physical indicators appearing as a result. The reasons for its deviation from the norm may be the features of the diet. However, sometimes an increase or decrease in the density of urine requires special tests to detect the presence of pathology.
Specific gravity of urine - what is it
The fluid excreted from the body is secondary urine. Unlike primary (similar in composition to blood plasma), it does not contain useful substances. It consists only of an excess volume of fluid and waste products (urea, acids, urobilin and salts - chlorides, sulfates and phosphates).
Healthy kidneys must cope with the task of excreting metabolic products in conditions of ingestion of both small and significant amounts of fluid. In the first case, the urine should become more dense, and in the second - diluted.
The specific gravity (density) of urine is a value that characterizes this ability of the kidneys - to ensure the constancy of the mass of metabolic waste excreted with any volume of secondary urine.
Norms in adults and children
The total volume of fluid involved in metabolic processes is not a constant value. Factors such as:
- air temperature;
- drinking regime;
- current time of day;
- the presence of salty or spicy food in the menu;
- the amount of fluid released during sweating and breathing.
However, in a normal adult, the variations should be in the range of 1.014-1.025 g / liter (normostenuria).
During pregnancy, the spread of daily values \u200b\u200bmay be wider - 1.003-1.035. The reasons for this are partly toxicosis, nausea and vomiting, which causes dehydration.
If there is a deviation of the indicator (in the analysis form -), the following are distinguished:
- - SG fluctuations within limited limits - 1.010-1.012;
- hypostenuria– decrease in SG less than 1.010 (1.008);
- hyperstenuria– increase in SG to 1.025 (1.030) and higher.
An increase in density can also be initiated by factors such as:
- the presence of sugar in the blood– 1% per 0.004 g/liter;
- the presence of protein in urine– 3g/liter of protein corresponds to an increase in SG of 0.001.
Normal specific gravity values for children can be tabulated:
In the general case, the excess of the norm for children is the value of the specific gravity of 1.020 g / liter.
Reasons for increasing the specific gravity
All existing reasons for the output of the urine density indicator beyond the normal range can be divided into physiological and pathological. The first factors independent of gender and age include:
- a feature of the drinking regime, expressed in insufficient fluid intake during the day:
- taking significant doses of drugs that are actively excreted with urine: (or rather, certain groups of diuretics that increase the excretion of urea and other substances with urine), as well as antibiotics;
- dehydration caused by frequent vomiting or diarrhea, as well as profuse sweating in hot weather or during intense physical exercise;
- burns of large areas of the body and trauma to the abdomen - naturally, both of these conditions require therapy, but the mechanism for the appearance of hyperstenuria is generally natural here.
Among the diseases that can cause a change in the laboratory indicator of SG, there are:
- heart failure, with accompanying edematous manifestations;
- diabetes mellitus, accompanied by a high concentration of sugar in urine;
- inflammatory diseases of the kidneys or lower urinary tract;
- or, on the contrary, start ;
- (hyperstenuria is combined with oliguria - a decrease in the amount of urine);
- diseases accompanied by ().
- endocrine pathologies.
Hyperstenuria in pregnant women
Laboratory parameters in women during the period of bearing a child can differ significantly from the norm, both due to physiological and treatment-requiring reasons. An increase in specific gravity may appear in connection with such phenomena as:
- toxicosis and accompanying dehydration, as well as a violation of the water-salt balance;
- preeclampsia (preeclampsia) - an increase in the specific gravity of urine occurs in conditions of extensive edema, a small amount of urine excreted and the presence of a large amount of protein in it.
Hyperstenuria in children
Impressive figures characterizing this indicator can occur in babies, both against the background of common causes, and have specific prerequisites:
- congenital or acquired pathologies of the urinary organs;
- frequent poisoning and gastrointestinal infections leading to diarrhea and vomiting.
- in infants, an increase in the specific gravity of urine may be associated with the peculiarities of the mother's diet - an excess of animal proteins, fatty foods, offal in it.
Reasons for the decrease in specific gravity
A change in the indicator should not cause concern if the decrease occurred under the conditions:
- abundant intake of fluid in the body;
- taking non-fast groups of diuretics (although a doctor's consultation may be required here);
- an unvaried diet characterized by insufficient protein intake. This also includes prolonged starvation, dystrophic conditions.
In the presence of a pathological process, urine becomes less dense in the absence of an excessive (but not pathological) drinking regimen.
This can happen under the following conditions:
- involuntary polydipsia - excessive fluid intake, not caused by physiological needs. The disorder often accompanies mental disorders or diabetes insipidus;
- central or renal diabetes insipidus;
- diseases of the central nervous system - encephalitis, meningitis;
- chronic renal failure;
In turn, provoke the development of diabetes insipidus of various types can:
- hereditary pathological conditions;
- head injuries and surgical interventions;
- infectious diseases;
- malignant neoplasms in brain tissues, accompanied by metastases;
- , including .
Features in pregnant women and children
In newborns, the specific gravity of urine often does not exceed 1.015-1.017. This value is considered normal during the first month of a child's life.
Women may experience transient diabetes insipidus during pregnancy. It either does not require treatment at all, or allows symptomatic therapy according to the type of central syndrome. If it is of a nervous nature, a psychiatric consultation may be required.
Diagnostic methods
Unable to accurately determine specific gravity due to the fact that the concentration of substances dissolved in urine during the day can vary significantly. It is not within his power to differentiate the cause of the violation that has arisen. Therefore, the following types of functional research are used:
- - a type of diagnosis, during which the ability of the kidneys to excrete fluid, as well as to concentrate and dilute urine, will be determined. It is carried out without changing the drinking regimen and consists in collecting 8 portions of urine for knocking (after 3 hours). Each portion is measured by the volume of urine and its specific gravity. The result of the analysis will be the spread of density figures per day and the difference between daytime and nighttime diuresis. Further analyzes are prescribed only in case of a doubtful result of the Zimnitsky test or if obvious deviations are found;
- concentration test (with dry food)- is carried out with the elimination of liquid foods and drinks from the patient's diet. Collect several daily portions of urine from 9 to 21 pm and one night. The test is not always advisable and has contraindications;
- breeding test- this tests the ability of the kidneys to dilute urine with excessive fluid intake. To do this, the person being examined needs to drink a certain amount of water, calculated based on the weight of his body. There are groups of patients in whom the study is carried out with caution or is completely contraindicated.
The specific gravity of urine is an indicator in which the average person rarely shows increased interest. However, it can also be a source of information needed by the clinician in assessing kidney function and sometimes in diagnosing non-renal pathologies.