General urine analysis
For qualitative research of urine its morning portion is used. The general analysis of urine determines its transparency, color, odor, pH, relative density, the presence of protein, leukocytes, erythrocytes, cylinders, epithelial cells, salts( urates, oxalates, phosphates), etc.
Transparency is determined visually. The urine is placed in a test tube or cylinder of clear glass and the transparency is evaluated in transmitted light. Normal urine is transparent. With prolonged standing, a cloud of mucus forms in it. Opacity of urine is noted in the case of the content of impurities in salts, large amounts of mucus, cellular elements, bacteria or lipids.
The cause of urine turbidity is determined by microscopic examination of its sediment or by chemical analysis.
1. If, after heating on a spirit-lamp, 2-3 ml of urine in the urine tube disappears, then the sample contains a large amount of urates( uraturia).
2. If the turbidity is retained after heating the portion of urine, and when a few drops of acetic acid disappears, phosphaturia is determined.
3. If the disappearance of the muti is accompanied by a hiss with the addition of acid, then carbonates are present in the urine.
4. If the turbidity disappears with the addition of dilute hydrochloric acid, then the urine contains a large number of oxalates( oxaluria).
5. If the urine becomes transparent when a concentrated potassium hydroxide solution is added to it, uric crystals are found in the urine.
6. If turbidity disappears when added to 2-3 ml of urine ether, then the urine contains lipids( lipuria).
The color of is determined by examining urine in reflected and transmitted light. Normally, the newborn urine is almost colorless. On the 2-3rd day after birth, it acquires an amber-brown color, which is associated with the release of a large number of urates. In young children, the color of urine is straw-yellow, at a later age its color varies from straw to amber-yellow. Normal color of urine depends on the presence of urochrome in it. In diseases of the liver, heart, hemolytic conditions, hyperthyroidism, as well as in conditions leading to a decrease in the amount of urine( such as fever, vomiting, diarrhea, increased sweating, toxicosis, etc.), hyperchromia is observed. The weakly colored urine( hypochromy ) is characteristic of polyuria in chronic renal failure, sugar and diabetes insipidus, etc. The color of urine may vary depending on the pathological process, the use of medications( Table), and also in response to certain foods( beets, carrots, blueberries).
Smell. Normally, urine produces a weak aromatic odor due to its volatile fatty acids and other substances. A sharper smell is associated with the presence of a urinoid in the urine. At a diabetes in urine there is an acetone, the smell of rotten apples is felt. With the ammonia decomposition of urine, the smell of ammonia comes from it. The nature of the smell affects the content of excreted drugs in the urine.
Table
Change in color of urine depending on various causes of
pH reaction of urine. In a general analysis, the pH of urine is roughly set by litmus test pieces. To determine the reaction, only fresh urine is taken. When standing urine, C02 is released from it, and the pH shifts to the alkaline side. The urine reaction is determined by the simultaneous use of two kinds of litmus paper - blue and red. The following results are possible:
• blue litmus paper blushes, red does not change colors - acid reaction;
• red litmus paper turns blue, blue does not change color - alkaline reaction;
• both types of paper do not change colors - neutral reaction;
• Both types of paper change color - amphoteric reaction.
More accurately, the pH can be determined using an electrometric pH meter. Acidity of urine in children increases with renal failure, diabetes, kidney tuberculosis, leukemia and other diseases leading to acidosis. Shift of the urine reaction towards alkalinity is noted during vomiting( in connection with the loss of chloride ions), with resorption of edema, plant foods and conditions leading to the development of alkalosis in the body.
Relative density. It is determined by special hydrometers called urometers. The scale of the meter shows divisions from 1,000 to 1,060.The meter also indicates to what ambient temperature the calibration is calculated. Usually this is 15 ° C.If the temperature of the urine under study does not coincide with the temperature at which the meter is calculated, after correction of the relative density, a correction is made: for every 3 ° C, add or subtract 0.001, depending on whether the urine temperature is higher or lower than 15 ° C.To determine the relative density, urine is slowly poured into a narrow cylinder, without causing the formation of foam. The cylinder is installed strictly vertically on a stable table, and the urine is carefully immersed in the urine. When the dive of the meter ends, it is slightly pushed from above, but so that the part remaining above the liquid is dry. After the termination of oscillations of the meter, the relative density of urine divided by the scale of the urometer coinciding with the lower meniscus is noted. If sugar or protein is present in the urine, an amendment must be made to obtain the final value of the relative density. Each percent of sugar increases the density of urine by 0.004, and every 3% of the protein - by 0.001.Thus, if the urinary protein content exceeds 3%, the correction is calculated from the obtained relative urine density on the basis of the data given below.
Determination of the relative density of urine using hydrometers is a fairly simple and sufficiently accurate method for practical purposes. However, in children, especially the early age, it is not always possible to collect the right amount of urine, so that it can immerse the hydrometer. In such cases, urine is often diluted 2 or 3 times with distilled water, and the established indicator of the relative density of diluted urine is multiplied by the dilution rate. The indicators of relative density of urine are of great importance for the clinic, because they allow the doctor to judge the ability of the kidneys to concentrate and dilute the urine. Relative density of urine depends on the concentration of substances dissolved in urine. The relative density of primary urine is the same as that of plasma, 1.010, and the final urine density can range from 1.001 to 1.040.If the renal function is impaired, urine is concentrated and diluted( as observed in nephritis and other diseases), the relative density of urine becomes close to the plasma density or the same. The difference between the lowest and the highest specific gravity, at least 10( 1010-1020), is an indicator of the normal concentration ability of the kidneys. When the relative density of urine is below 1010, hypostenuria is diagnosed, and within the difference less than 10 isostenuria. In newborns and children of the first year of life, physiological hypo- and isostenuria is observed. In the older age, the relative density of the morning portion of urine can reach 1,020-1,025.However, in order to determine the true functional capacity of the kidneys, multiple studies of the relative density of urine are necessary for 7-10 days. To this end, with suspicion of the disease, kidney parenchyma and a decrease in their function are put special tests for breeding and concentration.
Microscopic examination of urine sediment. Examination of urinary sediment is of great importance for the diagnosis of many diseases of the kidneys and urinary tract, allows you to judge the form and phase of the disease, monitor the effectiveness of the treatment. Elements of urine sediment are divided into two groups: organic sediment and inorganic. The most important information for clinical practice is obtained by examining the organic sediment. It includes red blood cells, leukocytes, cylinders and epithelial cells. The inorganic precipitate can be represented as crystalline or amorphous particles of salts of phosphates, oxalates, urates, uric acid. Approximate, quantitative and special methods are used to study urine sediment. With the usual general analysis of urine using microscopy, one can obtain only an approximate idea of the composition and quantitative ratios of urinary sediment. To study urinary sediment in a routine assay, 10-15 ml of urine is placed in a centrifuge tube and centrifuged for 5 minutes at 1000-1500 rpm. Then, the supernatant is drained and the precipitate is mixed with 0.5 ml of urine, applied to the slide in a thin layer and examined under a microscope on an average magnification. In this case, the nature and number of uniform elements in the field of view are noted. If pointing to single elements, then the element does not occur in each field of view. For greater reliability, the analysis conditions are standardized, i.e.always take the same amount of urine, centrifuge at the same number of revolutions per minute for the same time and the sediment is treated at the same magnification. Urine should be examined no later than 1 hour after excretion, as when standing its cells are destroyed due to ammonia decomposition, changing pH.
Erythrocytes. In the urine of a healthy person, in normal analysis, they are not detected or single elements are detected. With glomerulonephritis, tuberculosis, polycystic kidney, kidney tumor, hemorrhagic vasculitis, collagenosis, bladder inflammation and other erythrocyte diseases in urine can be a significant amount. There are macro- and microhematuria. With macrohematuria, macroscopically, it can be noted that the color of urine is changed. Due to the presence of a large number of red blood cells in the urine, it becomes red, or the color of meat slops. In microhematuria, erythrocytes are detected only by microscopy of the sediment. Penetration of erythrocytes in urine with glomerulonephritis, intoxication is caused by increased permeability of glomerular capillaries and their ruptures. With inflammatory diseases of the urinary tract, pelvis, ureter, bladder stones, erythrocytes enter the urine from the damaged mucous membranes. Erythrocytes penetrating into the urine from the glomerular capillaries passing through the tubular nephron system often lose hemoglobin and appear empty under the microscope( "erythrocyte shadows", "leached red blood cells"), while erythrocytes from the mucous membranes contain hemoglobin and are evaluated as "fresh red blood cells".When collecting urine in portions( two-glass and three-glass samples) during a single urination, it is possible to find out from which segment of the urinary system hematuria comes from. So, with hematuria from the urethra, there may be blood clots in the first portion of the urine. If the hematuria is caused by acute inflammation of the mucosa, stone or other diseases of the bladder, more blood will be excreted with the last portion of the urine. In hematuria associated with damage to the ureter, fibrin molds, sometimes corresponding to the lumen of the ureter, are sometimes found. If hematuria with diffuse kidney disease, excreted urine is colored uniformly.
Leukocytes. In the urine of a healthy person, they can be single in the field of vision. Detection of 5-7 leukocytes in each field of vision indicates an inflammatory process in the urinary tract. However, in this case, it should always be excluded that white blood cells enter urine from the external genitalia, which happens in phimosis, balanitis and balanoposthitis in men( boys) and vulvovaginitis in women( girls).Two- and three-glassed samples are widely used in leukocyturia.
Cylinders. In urine, they can be in the form of hyaline, granular, epithelial and waxy casts. All of them can be formed in pathological conditions in the kidneys. Cylinders in the urine of a healthy person are rare. They are often found in quantitative methods of studying urinary sediment. As a rule, these are hyaline cylinders, which are a protein curdled in the lumen of the tubules. Epithelial cylinders indicate a lesion of the renal parenchyma and consist of glued epithelial cells of the renal tubules. With a more pronounced dystrophic process, the kidneys appear grainy and waxy cylinders. These are the impressions of the rejected cells of the tubular epithelium, subjected to fatty degeneration. In addition, in the urine sediment can be found cylinders formed from the elements, hemoglobin, methemoglobin blood. The basis of these cylinders is usually protein.
Cylinders are similar to hyaline cylinders of formation, consisting of crystals of salts of urate ammonium, mucus, leukocytes, bacteria. Cylindroids are found in the recovery phase with acute glomerulonephritis. From hyaline cylinders they differ in the heterogeneity of the structure.
Inorganic sediment. Excessive release of elements of inorganic sediment in the urine can lead to the formation of stones in the urinary tract. Uraturia - increased urinary excretion of uric acid salts. It is observed in the first days of life of newborns. Due to a significant number of urates, the urine of newborns can have a brick-red color. The large disintegration of cellular elements in newborns often leads to the formation of a uric acid infarction, which by the end of the first week of life passes. Urturia in older children can be associated with eating a large amount of meat, can occur with muscle overwork, fever. Hyperuraturia can be caused by hereditary hyperuricemia, which is especially pronounced in the Lesch-Nihan syndrome. Oxalaturia - increased excretion in the urine of calcium oxalate, may be associated with eating foods rich in oxalic acid. Such products include sorrel, spinach, tomatoes, green peas, beans, radish, tea, coffee, etc. The cause of oxalaturia is also the pathological process in the child's body, accompanied by the disintegration of tissues( dystrophy, tuberculosis, diabetes, bronchiectasis, leukemia, etc..).Oxalaturia is also known as a hereditary disease, often complicated by nephrolithiasis and chronic pyelonephritis. With severe oxalaturia, the oxalate content in daily urine is 3-4 times or more higher than the permissible value( the norm is 8-10 mg%).Phosphaturia - increased excretion of urine salts of phosphates precipitating in the alkaline urine. It is observed when eating plant products( vegetables, fruits, etc.), as well as in the inflammatory process in the mucosa of the urinary tract, when bacterial fermentation and alkalinization of urine occur. Phosphaturia can be the cause of the formation of bladder stones.
Quantitative evaluation of urinary sediment elements. Determination of the number of erythrocytes, leukocytes, cylinders, Stern-gamer-Malbin cells, active leukocytes in the sediment has diagnostic and differential-diagnostic significance.