Urine analysis according to Zimnitsky: how to collect, decoding
The content of the article:
- How to collect urine for analysis according to Zimnitsky?
- Decoding the result of urine analysis according to Zimnitsky
-
Deviations from the norm and their causes
- Hypostenuria
- Hypersthenuria
- Polyuria
- Oliguria
- Nocturia
Urine analysis according to Zimnitsky is one of the most common methods of laboratory diagnostics, which allows you to assess the ability of the kidneys to concentrate and dilute urine.
The kidneys regulate the composition of urine through three processes: reabsorption - the absorption of fluid from the urine, filtration and secretion - the excretion of substances that are to be excreted into the urine. During these processes, the kidneys can osmotically concentrate or dilute urine, leaving only vital substances in the blood in the required quantities. The remaining liquid containing nitrogenous compounds (urea, uric acid, creatinine, glucose, purine bases, proteins, indican, etc.) forms secondary urine and is excreted.
Urine analysis according to Zimnitsky allows you to determine the volume of daily urine, its density, the concentration of salts in it Urine analysis according to Zimnitsky allows you to determine the volume of daily urine, its density, the concentration of salts in it
The specific gravity of urine shows the concentration of nitrogenous compounds dissolved in it, and the ability of the kidneys to excrete urine with a high concentration of toxins is an indicator of the normal nitrogen excreting function of the kidneys.
With a decrease in the flow of fluid, the volume of urine decreases, the concentration of nitrogenous salts in it increases, the color changes to rich yellow. The increase in fluid intake into the body, respectively, is accompanied by the excretion of a large volume of poorly concentrated and less colored urine.
Research according to Zimnitsky allows you to determine:
- total daily urine volume;
- distribution of the total volume of separated urine during the day;
- the concentration of substances dissolved in the urine;
- the relative density of each portion of urine.
The concentration of substances in the urine can vary significantly during the day, which is associated with the intake of water, food, loss of fluid by the body. Therefore, their determination in a single portion of urine is not very informative. Research according to Zimnitsky is to identify the relative density of each separately taken portion of urine.
The indication for the purpose of the analysis is the diagnosis of the following conditions:
- renal failure;
- chronic glomerulonephritis and pyelonephritis;
- diabetes insipidus;
- essential hypertension;
- pregnancy with toxicosis in the first trimester and gestosis in the last.
How to collect urine for analysis according to Zimnitsky?
As a rule, the doctor who prescribes the study tells where you can take the test and how to properly prepare for it. Urine for analysis according to Zimnitsky is taken in any clinical laboratory, but the reliability of the result directly depends on how responsibly the patient will react to the collection of material. Proper preparation of the patient for the delivery of urine ensures the reliability of the study result.
Algorithm for collecting urine for research:
- prepare in advance eight clean and dry containers (glass jars or plastic containers), number them and indicate the time of collection of a portion of urine;
- on the first day of collection, urination in the morning is not counted, the first portion of urine is released into the toilet;
- urine will need to be collected eight times throughout the day (for each urination - a new bottle), every three hours;
- immediately after urinating, the container is tightly closed and stored in the cold (best in the refrigerator);
- the volume of liquid and liquid food consumed during the day should be recorded;
- if during any three-hour interval there was no urge to urinate, then the jar corresponding to the missed time is left empty. And vice versa: if the container is filled before the end of the period of time, urine is collected in an additional container, indicating the number and time on it;
- in a day, all eight jars must be handed over to the laboratory.
The collection of urine is carried out at certain hours during the day, during the preparation, the rules are observed: during the analysis, diuretics should not be taken, and the intake of medications should be agreed with the doctor. Before collecting each portion of urine, hygiene procedures (washing hands, genitals) should be performed. There are no restrictions on food intake and drinking regime: the patient adheres to his usual diet, without unnecessary water load.
Decoding the result of urine analysis according to Zimnitsky
The total daily volume of excreted urine is determined using a graduated cylinder, summing up the daytime and nighttime diuresis. Normally, the total amount of excreted daily urine is 1500–2000 ml.
Comparing the daily diuresis with the volume of fluid that entered the body during the day, the percentage of fluid excreted in the urine is determined. The daily amount of urine should be 65–80% of the fluid you drink. Normally, there should be an increase in urination after drinking fluids.
The normal functioning of the kidneys is evidenced by the variation in the volume of collected urine. The amount of urine in portions varies on average from 50 to 300 ml, daytime diuresis prevails over nighttime.
Daily fluctuations in urine density are permissible in the range of 1.001–1.030 g / ml (according to some reports, up to 1.040 g / ml). The difference between the figures of the maximum and minimum density of urine should be greater than 7. During the daytime, 2/3 to 3/4 of the daily volume of urine should fall.
The relative density is determined using a laboratory instrument - an urometer, which looks like a float with an elongated thin neck, on which divisions are applied. Its principle of action is based on comparing the density of urine with the density of water. For analysis, the urometer is immersed in a transparent cylinder filled with urine so that it does not touch its walls. The deeper the urometer is immersed in the cylinder at a urine temperature of 20 ° C, the greater its specific gravity. The preserved concentration ability of the kidneys is indicated by indicators of the density of morning urine equal to or exceeding 1.018.
Table of reference values for urine analysis according to Zimnitsky
Index Reference values The volume of daily urine output 1500-2000 ml The proportion of fluid excreted in the urine 65-80% of the total amount of fluid consumed The ratio of daytime to nighttime diuresis 2: 1 Relative density 1.010-1.025 g / ml - for daily portions (at least one of the portions - at least 1.020-1.022 g / ml)
no more than 1.035 g / ml - in the night portion
Differences in urine volume in different portions 50 to 300 ml Differences in urine specific gravity 1.008 to 1.028 g In children, the ability of the kidneys to concentrate urine is reduced, therefore, the upper limit of the norm for the volume of daily urine output is greater for them, and the relative density of urine is less. Normal indicators of the relative density of urine in newborns are 1.002-1.020 g / ml. Then the level of density gradually increases and by the age of 5 it reaches 1.012–1.021. From the age of 12, this indicator reaches normal values for an adult.
During pregnancy, the rate of specific gravity of urine is 1.010–1.025 g / ml.
Deviations from the norm and their causes
In case of violations of the functioning of the kidneys in the analysis of urine according to Zimnitsky, deviations from the norm are revealed.
Hypostenuria
Hypostenuria is a decreased relative density of urine. Hypostenuria is diagnosed if urine density values are below 1.010 g / ml in all urine portions. Such a decrease may indicate the following disorders: chronic renal failure, chronic nephritis, glomerulonephritis, pyelonephritis, acute tubular necrosis, diabetes insipidus, heart failure, malignant hypertension, leptospirosis. Also, a reduced level of urine density can be a consequence of a lack of antidiuretic pituitary hormone, kidney damage with heavy metals, food dystrophy, polydipsia, and taking diuretic drugs. The reason for the decrease in the specific gravity of urine in pregnant women may be kidney disease, hormonal disorders, toxicosis.
Hypersthenuria
Hypersthenuria is an increased relative density of urine. Hypersthenuria is caused by large amounts of glucose or protein in the urine. It is observed with large extrarenal fluid losses, dehydration, massive blood loss, acute glomerulonephritis, lesions of the stomach and intestines with frequent vomiting and diarrhea, diabetes mellitus, circulatory failure, cardiac decompensation with increasing edema, toxicosis of pregnant women. An increase in the level of urine density may be the result of taking certain medications, X-ray contrast agents. In children, increased urine density is observed with uric acid diathesis.
The color of urine depends on the concentration of substances dissolved in it and varies from almost transparent white to dark yellow The color of urine depends on the concentration of substances dissolved in it and varies from almost transparent white to dark yellow
Polyuria
Polyuria is an increase in the volume of daily urine with a low specific gravity. The cause of polyuria can be chronic renal failure, kidney stones, pyelonephritis, sarcoidosis, diabetes mellitus, heart failure, prostate disease.
Often polyuria accompanies pregnancy, especially the third trimester, due to the strong pressure of the enlarging uterus on the bladder.
Oliguria
Oliguria - a decrease in the volume of daily urine. Oliguria can be caused by nephrological diseases (glomerulonephritis, renal vein embolism, pyelonephritis, acute renal failure), hemolytic anemia, urinary tract obstruction, heart failure. A slowdown in urine production can be caused by increased sweating, diarrhea, vomiting, bleeding, restriction of the drinking regime, prolonged fasting, and taking certain medications. During pregnancy, a decrease in the volume of daily urine may be caused by compression of the ureters by an enlarged uterus.
Nocturia
Nocturia is an increase in the amount of urine excreted at night. The predominance of nocturnal over daytime diuresis may indicate the development of heart failure, nephrosclerosis, atherosclerosis of the renal arteries, chronic glomerulonephritis, pyelonephritis, cystitis, liver cirrhosis. Prostate adenoma, diabetes insipidus, pernicious anemia, thyroid diseases can also cause nocturia.
If any indicators deviate from the norm, they resort to clarifying diagnostics - they additionally pass both laboratory tests (clinical, biochemical blood test, bacteriological examination of urine) and instrumental (ultrasound, excretory urography) studies.
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Anna Kozlova Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
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