Hematuria (erythrocyturia) is the presence of red blood cells in the urine. Hematuria is a symptom of a pathological condition of the body. Hematuria does not always indicate pathology in the kidneys and urinary tract.
In the urine of a healthy person, erythrocytes can be detected by quantitative methods. According to the Nechiporenko method, up to 1000 erythrocytes are normally detected in 1 ml of urine.
By visual sign, hematuria is divided into macro- and microhematuria.
Changes in the color of urine visible to the eye (red color of varying intensity) indicate the excretion of blood in the urine and are called gross hematuria.
Macrohematuria appears when the blood content is about 1 ml in 1 ml of urine.
Microhematuria is characterized by the presence of erythrocytes in the urine, but without changing its color. Microhematuria can only be detected with a microscope or test strip. To clarify the causes of hematuria, in addition to the number of erythrocytes, their morphology is of certain importance. With hematuria, altered and unchanged erythrocytes are excreted in the urine.
The nature of changes in erythrocytes in hematuria (unchanged - retained pigment; altered - lost hemoglobin) is determined by the presence of hemoglobin in them and indicates the duration of bleeding and the residence time of erythrocytes in the urine. In the process of loss of pigment by erythrocytes and changes in their morphology, pH and relative density, osmolarity of urine play a significant role.
In slightly acidic and neutral (pH 6.5-7.5) urine, erythrocytes remain unchanged for a long time. A rapid loss of hemoglobin occurs under conditions of hypoisostenuria, with a high relative density of urine or acidic and sharply acidic (pH 5.5-6.0) reactions. Erythrocytes with hematuria undergo changes when they enter the urine with a low relative density from any part of the urinary tract.
Unchanged erythrocytes in the urine are more common in urological diseases:
- chronic pyelonephritis
- kidney tuberculosis
- chronic renal failure (with urine specific gravity of 1.015-1.017)
Changed red blood cells in urine are found when:
- stagnant kidney (with urine specific gravity of 1.020-1.027)
The detection of erythrocyte casts may serve as evidence of the glomerular genesis of hematuria. Also, morphologically, altered erythrocytes that have passed through the basement membrane, with glomerulonephritis, are deformed, take the form of acanthocytes, the number of which may be more than 10%, the so-called dysmorphic erythrocytes, may also more likely indicate in favor of glomerular hematuria.
Types of hematuria
Distinction is made between prerenal, renal, and postrenal hematuria.
Prerenal hematuria occurs, as a rule, in diseases accompanied by hemorrhagic syndrome, due to an impaired permeability of the capillary wall or the hemostatic system. Prerenal hematuria is more often observed in the form of microhematuria.
Renal hematuria is caused by damage to the vessels of the renal glomeruli. The evidence of the glomerular genesis of hematuria can be the presence of erythrocyte casts and morphologically altered erythrocytes.
Diseases in which significant hematuria may occur:
- hematuria in some acute nephritis complicating infectious diseases (scarlet fever, influenza, rubella, tonsillitis), often in the form of microhematuria
- hematuria with glomerulonephritis
- hematuria with nephrosclerosis
- hematuria with kidney stones
- hematuria in kidney cancer
- hematuria of embolism and kidney infarction
- hematuria with kidney tuberculosis
Postrenal hematuria is caused by bleeding from the urinary tract, rupture of a vessel in the prostate.
The most common causes of postrenal hematuria are cystitis or urethritis, urinary tract stones, tumor, and prostate hypertrophy.
For topical diagnosis of erythrocyturia in urological practice, a two- and three-glass test is used.
Interpretation of sample results:
- discharge of blood before urinating indicates its origin from the urethra
- the predominance of erythrocytes in the first portion of urine is observed with damage to the urethra
- the predominance of erythrocytes in the first and third portion of urine - with damage to the prostatic part of the urethra
- the predominance of erythrocytes in the third portion of urine is characteristic of the lesion of the bladder; sometimes blood appears only in the last drops of urine
- an even distribution of red blood cells in all three portions is found in kidney damage; the presence of erythrocyte casts confirms the renal origin of erythrocytes