Hematuria
Update December 26, 2018
Hematuria is >3 RBCs/high power field on microscopy on three urinalyses, a single urinalysis with >100 RBCs, or gross hematuria) indicative of bleeding from the urinary tract.
A clean-catch midstream urine collection is appropriate for most patients.
Catheter-collected specimens are recommended for women with a vaginal discharge or menstrual or vaginal bleeding; however, urethral catheterization induces hematuria in 15% of patients.
A single urinalysis with hematuria is common and can result from menstruation, viral illness, allergy, exercise, or mild trauma.
Hematuria can be detected by dipstick.
A urine dipstick test for blood can detect as little as 150 micrograms/L of free hemoglobin, corresponding to 5 to 20 intact RBCs/mL on microscopic analysis.
False-positive results occur in the presence of free hemoglobin, myoglobin (rhabdomyolysis), or porphyrins. (where no RBCs are seen on urine microscopy).
False-negative results may also be obtained with urine dipstick tests for blood if the urine has a high concentration of ascorbic acid (>5 milligrams/dL) or a high specific gravity.
Urine is bright red or cola colored.
Causes
GU neoplasms (malignant and benign), polycystic kidneys, trauma, infection (urethra, bladder, prostate, etc), stones, glomerulonephritis (primary and secondary such as Wegener granulomatosis, SLE, and polyarteritis nodosa), renal infarction, renal vein thrombosis, enterovesical fistula, sickle cell anemia, vigorous exercise (runner’s hematuria), accelerated hypertension, factitious and vaginal and rectal bleeding. Bleeding diathesis and anticoagulation can unmask GU tract abnormalities.
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