Urinalysis

A general urine analysis is a test that is conducted in a special laboratory and is prescribed to a patient in the process of diagnosing a disease. A urine analysis consists of the following stages:

• Organoleptic examination - includes analysis of the amount of urine, its color, smell, foam and transparency.
• Physicochemical analysis of urine - makes it possible to determine the specific gravity and acidity level of urine.
• A urine biochemical test is performed to detect protein in the urine.
• Microscopic analysis of urine allows us to determine the degree of presence of red blood cells and white blood cells.

It is the data obtained from urine analysis that serves to identify chronic nephropathies, especially those that occur latently, and also allows one to assess the activity and, when performed dynamically, the rate of progression of kidney damage and the response to therapy.

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Urine collection

The midstream portion of morning urine is examined. Microscopy should be performed no later than 2 hours after urine collection. If immediate microscopy is not possible, urine should be stored at low temperatures to prevent bacterial proliferation and lysis of cellular elements (erythrocytes, leukocytes, cylinders). To preserve the integrity of erythrocytes and leukocytes, obviously alkaline urine is acidified. If it is impossible to follow the rules for collecting urine, for example, in patients with impaired consciousness, catheterization of the bladder is recommended.

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How to take a urine test?

Morning urine is usually taken for analysis. Before emptying the bladder, it is necessary to perform an intimate hygiene procedure using soap. Urine should be poured into a plastic container, which is sold in a pharmacy. Urine analysis is usually carried out no later than an hour and a half after collecting urine. Before taking a urine test, it is forbidden to take medications, as this can affect the results, and urine should not be left at sub-zero temperatures.

Urinalysis according to Nechiporenko

Urine analysis according to Nechiporenko allows to detect inflammatory processes occurring in the urinary tract and to determine the level of leukocytes, erythrocytes and cylinders. The following indicators are allowed as a norm: leukocytes - up to 2000 ml in males and up to 4000 ml in females; erythrocytes - up to 1000 ml; cylinders - up to 20 ml. Before donating urine, it is necessary to first prepare a dry plastic container, in which you then need to collect about 200 ml of morning urine (at least fifty to one hundred milliliters). Urine analysis is carried out as follows: the collected urine is shaken, then a little is collected in a test tube, which is centrifuged for several minutes, then the upper part of the urine is collected, and 1 milliliter of urine with sediment is left in the test tube, which is thoroughly mixed and placed in a special chamber, after which the number of leukocytes, erythrocytes and cylinders is counted.

Urine analysis during pregnancy

When pregnancy occurs, women have to take a urine test almost every week. The genitourinary system of a pregnant woman is subject to double the load, since during pregnancy not only the uterus increases in size, but also there is compression on the kidneys and bladder associated with the growth and position of the fetus. Therefore, taking a urine test during pregnancy is a mandatory regular procedure. For pregnant women, the presence of a small amount of protein in the urine may be normal, although in a normal state there is no protein in the urine. If more than three hundred mg of protein is found in the urine of a pregnant woman, this may signal kidney pathologies, including chronic ones, which may have worsened during pregnancy. In such cases, inpatient treatment is prescribed. Proteinuria (protein in the urine), which occurs in the 32nd week of pregnancy, may signal the development of nephropathy, accompanied by an increase in pressure, and dysfunction of the placenta. Various bacteria are often found in the urine of pregnant women. Bacteriuria can cause the development of pyelonephritis, which can cause a threat of premature birth. Urine analysis is especially important in asymptomatic bacteriuria, since this is the only way to detect hidden pathologies. There should be no leukocytes in the urine of pregnant women; elevated levels of salts may also indicate genitourinary disorders. If ketone bodies are detected in the urine of a pregnant woman, this may indicate the development of toxicosis. With a lack of potassium, as well as toxicosis, the acidity level in the urine may be reduced. Urine analysis during pregnancy includes a study of color and transparency, density, epithelium, bilirubin content, erythrocytes and cylinders. In case of unfavorable results, additional urine tests are prescribed - according to the Nechiporenko method, as well as urine culture, etc.

Microscopy of urinary sediment

The study of the constituent elements of urinary sediment is of great practical importance, including for establishing the level of localization of the pathological process in the urinary system. The elements of urine sediment are divided into organic (cellular elements, cylinders) and inorganic (crystals of various salts).

Among the organic elements of urine sediment, epithelial cells, erythrocytes, leukocytes and cylinders are examined.

Epithelial cells

Epithelial cells are differentiated by the type of epithelium. Squamous epithelial cells originate from the lower parts of the urinary tract; an increase in their content of more than 1-2 in the field of vision, in particular a large number of them indicates inflammatory processes in the bladder or urethra. The source of columnar epithelial cells is the renal pelvis and ureters; an increase in their number is observed in pyelonephritis and urethritis. The cells of the renal tubular epithelium are rounded, their detection in complexes with cylinders or in large groups indicates their renal origin. This type of cells is found in various kidney diseases (tubulointerstitial nephritis, chronic glomerulonephritis, including lupus).

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Erythrocytes

Erythrocytes are found in the urine sediment of healthy individuals in quantities of 0-1 per field of vision.

The presence of macrohematuria in a patient is judged by a characteristic change in the color of urine; there are special tests to distinguish it from myoglobinuria and hemoglobinuria (“Hematuria”).

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Leukocytes

Leukocyturia is an increase in the content of leukocytes in the urinary sediment (the norm is 0-1 in the field of view of the microscope in men and up to 5-6 in women). To accurately determine the source of leukocyturia, differential diagnostic tests are used to establish the population composition of leukocytes in the urinary sediment.

Infectious leukocyturia is distinguished, which is characteristic of many infectious and inflammatory diseases of the urinary system (including pyelonephritis). The infectious nature of leukocyturia can be roughly judged by the detection of bacteria in the urinary sediment - bacteriuria (more than 1x10 ⁵ /ml of urine). When conducting urine culture, false negative results are often obtained due to the fact that the accuracy of this method is affected by even minor violations of the rules for collecting and storing samples. Aseptic leukocyturia, characteristic of many forms of chronic glomerulonephritis, analgesic nephropathy; sometimes observed in amyloidosis.

Cylinders

Casts are formed by the combination of Tamm-Horsfall uromucoid (a protein secreted by the epithelial cells of the ascending limb of the loop of Henle in the norm), plasma proteins that have passed through the glomerular membrane, and specific components (cells, fat particles).

• Hyaline casts consist only of protein molecules; they are found in various kidney diseases and in the norm (no more than 100 in 1 ml of urine).
• Waxy casts are composed of plasma proteins and are a sign of chronic nephropathy.
• Cellular casts (erythrocyte, leukocyte) are always of renal origin and indicate damage to the renal parenchyma.
• Fatty casts are found in cases of significant proteinuria, including nephrotic syndrome.
• Granular casts are a sign of kidney disease.

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Inorganic elements of urine sediment consist of crystals of various salts

The detection of uric acid crystals, calcium oxalate, amorphous urates and phosphates, and triple phosphates in the urine is not in itself a sign of kidney damage; urine analysis and clinical data should be taken into account.

The presence of cholesterol, cystine, tyrosine and leucine crystals in urine always indicates kidney damage. Cholesterol crystalluria is observed in patients with nephrotic syndrome; tyrosine and leucine crystals indicate prognostically unfavorable liver damage.

Bacteria, fungi, protozoa, and parasites are also found in the urinary sediment. Bacteriuria is most significant in combination with leukocyturia; to clarify its genesis, it is advisable to conduct a bacteriological examination of the urine. Of the fungi, representatives of the genus Candida are most often found in the urinary sediment, especially in patients with diabetes mellitus or receiving immunosuppressive therapy. Amoebas are sometimes found; in the presence of dysuria, this indicates urogenital amebiasis. Detection of Schistosoma haematobium eggs indicates urinary tract invasion.

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General urine analysis: normal values

The normal color of urine ranges from light yellow to dark yellow. Too intense yellow color usually indicates increased density of urine, which is usually observed with dehydration, too light urine, on the contrary, indicates that the density is low. This means that there is a possibility of kidney failure. Any change in urine color from pale pink to dark brown may be an indicator of serious pathological processes. At the same time, the color of urine can also be affected by taking certain medications, as well as abundant consumption of beets and carrots. If the analysis showed that the urine is not transparent, this can be explained by the presence of bacteria, red blood cells, salts, fat, mucus, etc. If the urine is shaken, foam will appear on it. If the foam is cloudy, abundant and persistent, this may mean that there is protein in the urine. Normally, the foam is transparent and quickly soluble. If the protein level in urine is more than 0.033 g/l, this is considered a deviation from normal values.

Decoding urine analysis

Urinalysis includes assessment of the following parameters.

• Color, transparency.
• Relative density.
• Chemical tests:
  • pH;
  • protein;
  • glucose;
  • ketone bodies;
  • hemoglobin (usually determined by a corresponding change in urine color);
  • urobilinogen;
  • myoglobin (usually determined by a corresponding change in urine color).
• Microscopy:
  • crystals - urates, phosphate, oxalate or calcium carbonate, triple phosphate, cystine, medicinal;
  • cells - leukocytes, erythrocytes, tubular epithelial cells, urinary tract cells, atypical cells;
  • cylinders - hyaline, granular, erythrocytic, leukocyte, epithelial, waxy, granular, lipid;
  • infectious agents - bacteria, fungi, parasites.

Urine analysis involves mandatory determination of protein content, cellular elements (erythrocytes, leukocytes), bacteria and some other indicators. In addition, with the help of additional research methods, active forms of leukocytes are detected in urine, as well as the content of chemokines, growth factors and vasoactive molecules.

To diagnose microalbuminuria, a standard express test is used, which allows monitoring its value, including in outpatient settings.

Urine color and transparency

Freshly collected urine is normally transparent. The cause of urine turbidity is determined using additional tests.

• The disappearance of turbidity after heating the urine to 60 °C indicates an excess of urates and uric acid in it.
• If the urine becomes clear after adding 10% acetic acid, then it contains excess phosphates.
• If there is an excess of oxalates, the turbidity disappears after adding diluted hydrochloric acid.
• If the urine contains a large number of formed elements or mucus, it becomes transparent only after filtration and centrifugation.
• Turbidity that is resistant to all qualitative tests and centrifugation indicates bacteriuria.
• A persistent foam forms on the surface of urine containing a large amount of protein.

The urine of a healthy person is straw-yellow, the intensity of the color depends on the degree of its dilution. The urine of a patient with chronic renal failure is almost colorless. The change in the color of urine is also due to the presence of various chemicals in it, including drugs and their metabolites, as well as pus, blood and lymph.

Causes of urine color change

Color

Cause

White Red/pink/brown Yellow/orange Brown/black Green, blue

Lymph, pus, phosphate crystals Erythrocytes, hemoglobin, myoglobin, porphyrins, levodopa, methiddopa, metronidazole, phenacetin, phenolphthalein, food colorings Bilirubin, urobilin, iron preparations, nitrofurantoin, riboflavin, sulfasalazine, rifampicin, phenytoin Methemoglobin, homogensitic acid (in alkaptonuria), melanin (in patients with melanoma) Biliverdin, dyes (methylene blue and carmine indigo), triamterene, B vitamins, indican, phenol, chlorophyll, Pseudomonas aeruginosa infection

The milky white color of urine is due to the large amount of lymph or fats getting into it. Massive excretion of uric acid salts causes orange (brick) or brown coloration of urine. In porphyria, urine darkens when exposed to air.

Correct interpretation of the red color of urine is necessary. Fresh blood colors urine scarlet, hematuria of renal origin gives urine a characteristic appearance of "meat slops" - one of the signs of glomerulonephritis, including acute, myoglobin - red-brown color. In addition, red urine is noted when using methyldopa, phenothiazine derivatives.

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The smell of urine

Urine has a characteristic odor. It changes with various diseases, including metabolic ones.

Reasons for changes in urine odor

Smell	Cause
Sweetish, rotting fruit	Ketone bodies
Ammonia	Infection of the urinary tract with urea-splitting bacteria
Moldy	Phenylketonuria
Sweat	Presence of isovaleric or glutaric acids in the blood
Rancid fat	Hypermethioninemia, tyrosinemia

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Urine acidity

The urine reaction fluctuates widely (pH 4.5-8.5). A sharply alkaline urine reaction indicates the possibility of a urinary tract infection or renal tubular acidosis.

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Relative density of urine

The relative density of urine in a healthy person varies from 1.002 to 1.030. This indicator depends on the diet and fluid intake regime. Depression of the relative density of urine is an early sign of tubulointerstitial nephritis and chronic renal failure. To accurately determine this indicator, it is necessary to conduct the Zimnitsky test. With an increase in the protein content in the urine by 4 g / l or glucose by 2.7 g / l, this indicator increases by 0.001.

Urine analysis in children: decoding

In a general urine analysis in children, such parameters as color, smell, transparency, specific gravity, level of red blood cells and white blood cells, presence of protein, sugar, ketone bodies, salt, bacteria, and mucus are taken into account. Normal parameters are the absence of an atypical smell in urine and turbidity. If urine has an ammonia smell, this may indicate problems with the bladder. The acidity level in a child's urine varies from 4.8 to 7.5. With diarrhea, vomiting, as well as a predominance of plant foods in the diet and physical overexertion, an alkaline reaction occurs. Increased acidity of urine is observed with fever, diabetes, or excessive protein consumption. Normal urine density parameters are, depending on age, from 1.003 to 1.025. There should be no protein, sugar, red blood cells, cylinders, bacteria, salts, or ketone bodies in a child's urine. Such components may appear in case of metabolic disorders, kidney diseases, bladder, endocrine system, vomiting, high temperature, diarrhea, constipation, nervous tension, anemia. Increased leukocyte content may occur in case of inflammatory processes of the urinary system.

General urine analysis: decoding

Normal values for a healthy person:

• The colour is a moderate yellow, not too rich, but not too pale.
• Transparency is the norm.
• The smell is not strong.
• Acidity – pH less than 7.
• Density – from 1.018.
• Protein - no.
• Ketone bodies – no.
• Bilirubin - no.
• Urobilinogen – five to ten mg/l.
• Hemoglobin - no.
• Red blood cells – from zero to three per field of view for females, from zero to one per field of view for males.
• Leukocytes - from zero to six per field of vision in women, from zero to three per field of vision in men.
• Epithelium - from zero to ten in the field of view.
• Cylinders – no.
• No salt.
• Bacteria - no.