Very often in the clinic you can hear such a medical instruction - to make a test according to Zimnitsky. To the ignorant in medicine, these terms are mysterious and obscure, so let's try to figure out what it is.
Zimnitsky's test is a urinalysis aimed at examining the concentration function of our kidneys. Typically, this analysis is prescribed for chronic glomerulonephritis, chronic pyelonephritis, diabetes (diabetes insipidus), hypertension. The main goal of this analysis is to identify the functional ability of the kidneys.
The concentration function of the kidneys directly depends on the density of urine, its specific gravity. It should be remembered that in the urine mainly the products of the breakdown of proteins and nitrogenous slags are concentrated. If a high level of toxins is excreted in the urine, then this indicates normal renal function.
In this case, the amount of slag is expressed in specific gravity, which is very convenient for comparing this function in different age categories of patients. Specific gravity is the ratio of the weight of the solution to the weight of water, which is taken as a unit. The obtained indicator, first of all, reflects the ability to store water in the body or to remove it. Usually physiological abnormalities are found in children and the elderly.
A test according to Zimnitsky is a measurement of the relative density in the part of urine collected according to a certain scheme. Morning urine generated during the night is not tested, but then patients need to collect urine every three hours, that is, only eight servings per day. Zimnitsky's test is carried out in each portion separately. It is important to see a holistic picture of the indicators of all portions collected per day. If the kidneys are perfectly capable of osmotic dilution of urine and its concentration, then the volume of urine excreted will fluctuate - from fifty milliliters to three hundred. In this case, the amount of urine allocated during the day will prevail over the night. If urine is released more at night, then this phenomenon may be evidence of heart failure.
With the inability of the kidneys to concentrate urine, which Zimnitsky’s test can determine, isostenuria is diagnosed. The main indicator of isostenuria, which is obtained in the laboratory after analysis, is the low density characteristic of primary urine. And in chronic renal failure, they speak of hypoisostenuria, when low urine density is determined in all portions of collected urine. Upon receipt of such data from the laboratory, doctors usually suspect chronic human diseases, such as glomerulonephritis and pyelonephritis. But with a sharp amplitude of relative density in several portions, it is worth talking about diabetes insipidus.
In order for Zimnitsky’s test to be reliable, the analysis is done while maintaining the usual diet. Patients should not drink more liquid to give the necessary portions, otherwise the relative density of urine will be artificially reduced. However, for doctors it is important how much water was drunk - normally the human body excretes about sixty to eighty percent of all the water that came into it, and in the afternoon, urine is produced twice as much in volume.
Zimnitsky's test is a fairly informative analysis for doctors. But it is important for patients to correctly collect the test material so that the indicators are reliable. Urine sample must be collected in twenty-four hours, this includes the patient’s sleep time, but not from the field of awakening, but from it. In advance, you need to prepare containers (8 clean jars) and stick the name on them, clearly distinguish the number of the jar and the time for collecting urine into it. For three hours, you can urinate two or three times in one jar, which is designed for this time interval. After this, the urine belongs to the laboratory, and the results of the analysis are interpreted by the attending physician.