Hematuria is a laboratory symptom characterized by the presence of red blood cells in the urine. The causes may be inflammatory kidney diseases, urolithiasis, malignant neoplasms. Depending on the degree of hematuria, the color of urine can change to red, brown, “the color of meat slops”, but in the vast majority of cases remains unchanged. Excess of the norm is considered to be more than 3-5 red blood cells in the field of view during microscopy of urine sediment or more than 1000 in 1 ml when performing the Nechiporenko test. To correct this laboratory phenomenon, the treatment of the underlying disease is carried out.
By nature , the following types of hematuria are distinguished:
- Physiological (functional). Hematuria can be detected in absolutely healthy people in many cases. In young children, hematuria is caused by increased permeability of the immature renal filter. In adults, hematuria is noted after overheating, hypothermia, checking the Pasternatsky symptom, intense physical exertion or long hiking (marching hematuria).
- Pathological (organic). Organic hematuria is associated with various pathological processes – kidney diseases of infectious or autoimmune origin, the presence of concretions in the urinary tract, diseases with blood clotting disorders, etc.
According to the degree of severity , there are:
- Microhematuria. It occurs most often. Visually, the urine is not changed. Red blood cells are detected only during microscopic examination.
- Macrohematuria. The appearance of a large number of red blood cells in the urine, which acquires a characteristic color. Due to this, hematuria can be suspected already when examining urine with the naked eye.
By origin , hematuria is divided into:
- Renal. The most common form. Blood in the urine appears due to various kidney diseases – pyelonephritis, glomerulonephritis, kidney tumors.
- Prerenal. The presence of blood in the urine is caused by congenital or acquired coagulopathies – immune thrombocytopenia, hemophilia, prolonged use of antiplatelet agents or anticoagulants.
- Postrenal. Hematuria occurs in the pathology of the lower urinary system – the presence of concretions, polyposis of the bladder, hemorrhagic cystitis.
When studying the physico-chemical properties of urine with the help of test strips, it is possible to obtain false results for blood:
- False negatives. A negative urine test for blood can be obtained with insufficient mixing of the urine sample, a high concentration of ascorbic acid.
- False positive. False hematuria occurs when bacteria containing the enzyme peroxidase are present in the urine, disinfectants with hypochlorite are deposited on the walls of dishes for collecting urine, when the antiseptic betadine enters the urine. Also, a common cause of false hematuria is a violation of the preanalytic stage, for example, passing a urine test during menstrual bleeding.
Causes of renal hematuria
The main reason for the appearance of blood in the urine of children. In glomerulonephritis, erythrocytes enter the urine through the capillary wall of the glomeruli of the kidneys damaged by the inflammatory process. When passing through the glomerular capillaries, blood cells deform, which is considered a characteristic feature of urine microscopy. With chronic glomerulonephritis, moderate or insignificant hematuria is noted.
With an exacerbation of inflammation, the number of red blood cells in the urine is very high, up to macrohematuria with a change in the color of urine. A combination with leukocyturia and proteinuria is often observed. After specific therapy, hematuria disappears quickly enough. Pathologies of the glomeruli include:
- Post-streptococcal glomerulonephritis.
- IgA-nephropathy (Berger’s disease).
- Glomerulonephritis in collagenoses: lupus nephritis in systemic lupus erythematosus, scleroderma kidney in systemic scleroderma.
- Glomerulonephritis in systemic vasculitis: Schenlein-Henoch hemorrhagic vasculitis, polyarteritis nodosa, Wegener’s granulomatosis.
- Kidney damage in hepatitis B and C.
Hematuria is observed in approximately 30% of patients with acute or exacerbation of chronic pyelonephritis. The inflammatory process in the renal pelvis leads to blood entering the renal tubules. However, the number of red blood cells is insignificant or moderate (up to 15-20). Hematuria is always accompanied by leukocyturia, bacteriuria, a positive test for nitrites. After antibacterial therapy, blood, as a rule, is not detected in the urine.
Necrotic kidney lesions
The destruction of the renal tissue of a necrotic nature is accompanied by pronounced hematuria. This condition can be caused by acute thrombosis of the renal veins, embolism of the renal artery by thrombotic masses formed in the cavities of the heart during atrial fibrillation or infectious endocarditis. Papillary necrosis is also found – a specific complication of severe pyelonephritis in patients with diabetes mellitus.
Hematuria occurs, as a rule, acutely, against the background of dull or aching pain in the lower back, combined with leukocyturia. After thrombolytic, anticoagulant therapy, surgical removal of a blood clot or an entire kidney, a small amount of blood may be present in the urine for some time.
- Polycystic kidney disease;
- Tuberculosis of the kidneys;
- Kidney tumor;
- Tubulointerstitial nephropathies;
- Congenital anatomical defects of the urinary system;
- Hemolytic-uremic syndrome;
- Essential cryoglobulinemia;
- Alport syndrome.
Causes of postrenal hematuria
The most common cause of hematuria in adults. The mechanism of occurrence of hematuria in ICD is associated with trauma by concretion of the renal pelvis or ureteral wall. Blood appears during an attack of renal colic, accompanied by severe pain syndrome, nausea, vomiting. The degree of hematuria depends on the amount of damage.
Microscopy often reveals a large number of different crystals – calcium oxalates, phosphates, crystals of ammonium uric acid, uric acid. Due to the formed obstruction to the outflow of urine, infection often joins, as evidenced by the detection of leukocytes and bacteria in the urine. Outside of an attack, there is usually no blood. Hematuria completely stops after surgical removal of concretions.
Diseases of the lower urinary tract
Hematuria with cystitis is quite rare, more often it is noted with polyposes or bladder stones. Hemorrhagic cystitis with pronounced hematuria is possible – with schistosomiasis (parasitic invasion) of the bladder or as an adverse side reaction to prolonged use of the cytostatic drug cyclophosphamide.
With a bladder tumor, hematuria is considered a permanent symptom, and in people suffering from inflammation of the prostate gland or urethra (prostatitis, urethritis), it is extremely rare. In this case, hematuria is accompanied by leukocyturia, sometimes bacteriuria.
Causes of prerenal hematuria
The presence of red blood cells in the urine may be associated with a malfunction of the blood clotting system. These include congenital or acquired coagulopathies (thrombotic thrombocytopenic purpura, immune thrombocytopenia and other hemorrhagic diathesis), including against the background of the use of medications (anticoagulants, antiplatelet agents).
Also, blood enters the urine due to increased hydrostatic pressure in the renal vessels, which occurs in cardiovascular diseases – chronic heart failure and malignant arterial hypertension. Congestive hematuria quickly subsides after the improvement of the pumping function of the heart and normalization of blood pressure.
If hematuria is detected, it is necessary to consult a general practitioner, a nephrologist or a urologist to find out the cause of its development. Physical and anamnestic data are of great importance in the differential diagnosis of the etiological factor. It is specified whether an upper respiratory tract infection preceded the appearance of hematuria, what medications the patient takes, what chronic diseases he suffers from.
The doctor examines the skin, determines the presence of edema, measures blood pressure, body temperature, performs auscultation of the heart, asks about lower back pain, checks Pasternatsky’s symptom. To clarify the localization of the bleeding site, a 3-cup sample is carried out: the predominance of blood in 1 portion of urine indicates a lesion of the urethra or prostate, in 2 – a lesion of the bladder, in 3 or in all portions – renal hematuria.
When analyzing urine, attention is drawn to the presence of other changes – leukocyturia, proteinuria, bacteriuria. Microscopic examination of urine sediment determines the ratio of unchanged and dysmorphic erythrocytes. The presence of more than 75-80% of red blood cells with altered morphology indicates a lesion of the glomeruli of the kidneys. Also in favor of glomerular pathology indicates the detection of erythrocyte cylinders, acanthocytes.
If a positive reaction to blood with test strips is noted during a general urine analysis, and red blood cells are not detected during microscopy, a differential diagnosis with hemoglobinuria and myoglobinuria may be required, because the reagent zone of test strips is equally sensitive to red blood cells, free hemoglobin and myoglobin. Additional research methods are assigned:
- Blood tests. In the general blood test, the level of hemoglobin, ESR, shaped elements (platelets, leukocytes, erythrocytes) is measured, in the biochemical blood test, the concentration of urea, creatinine, CRP is measured, the GFR is calculated. Coagulation parameters are examined in the coagulogram.
- Immunological studies. If post-streptococcal glomerulonephritis is suspected, an anti-streptolysin-O test is prescribed. To confirm collagenoses, the detection of autoantibodies is required – to double-stranded DNA, topoisomerase, to the cytoplasm of neutrophils.
- Microbiological studies. To identify the pathogen in pyelonephritis, cystitis or infection of kidney stones, a bacterial culture is prescribed to determine sensitivity to antibiotics.
- Ultrasound. With pyelonephritis, an ultrasound of the kidneys visualizes the expansion of the cup-pelvic system, with ICD – the presence of concretions. In prostatitis, ultrasound of the prostate gland shows an increase in its size, a decrease in its echogenicity. The Doppler mode allows you to assess the state of renal blood flow.
- Excretory urography. On the basis of radiography after the introduction of a contrast agent, it is possible to detect an obstruction of the MVP, which may indicate ICD, polyps, tumors, abnormalities of the structure of the MVP.
- Cystoscopy. To clarify the nature of the bladder lesion (interstitial cystitis, tumor, polyp), some patients are prescribed cystoscopy.
- Histological studies. In order to establish the exact type of glomerulonephritis (membranoproliferative, mesangioproliferative, etc.), a kidney biopsy is performed. Morphological examination is also indicated in cases where a malignant neoplasm or systemic vasculitis is suspected.
There are no independent methods of hematuria correction. To eliminate this laboratory phenomenon, it is necessary to conduct therapy of the underlying disease. If hematuria develops while taking an anticoagulant, it is recommended to reduce the dosage or completely cancel it. The following medications are used as conservative therapy:
- Antibiotics. For the treatment of pyelonephritis, first-line drugs are penicillins, cephalosporins. With cystitis, fosfomycin trometamol is prescribed. Fluoroquinolones and macrolides are effective for prostatitis.
- Glucocorticosteroids. Preparations of adrenal cortex hormones (prednisolone) are able to suppress the severity of inflammation in the glomerular apparatus and autoimmune destruction of platelets in hemorrhagic diathesis.
- Cytostatics. Cytostatic agents (azathioprine, cyclosporine) are resorted to in severe glomerulonephritis, especially in vasculitis and collagenosis. Also, combinations of chemotherapeutic drugs are prescribed for tumors of the kidney, bladder.
- Alpha-blockers (tamsulosin). This group of drugs has a relaxing effect on the walls of the ureters and sphincters of the bladder, which contributes to the independent discharge of small-sized concretions.
- Alkaline solutions. Potassium citrate or sodium bicarbonate are used to dissolve uric acid stones.
- Cardiological preparations. Patients with chronic heart failure and arterial hypertension are prescribed beta-blockers, ACE inhibitors, potassium-sparing diuretics.
Patients with urolithiasis undergo shock wave lithotripsy or laparoscopic removal of stones, with polycystic, benign tumor, kidney infarction – resection, nephrostomy or total nephrectomy. With a pronounced bilateral lesion of the renal tissue with the development of terminal renal insufficiency, kidney transplantation can be performed for vital indications.
Hematuria is a rather serious clinical and laboratory sign, if detected, you should immediately contact a specialist. The prognosis for life is determined by the disease in which blood appeared in the urine – the most favorable for cystitis or prostatitis and extremely unfavorable for rapidly progressing glomerulonephritis or kidney tumors.