Hematuria
Hematuria, whether microscopic or gross, is a red flag that demands careful evaluation and must not be ignored. It is the most common presenting sign of urinary tract cancer and parenchymal renal disease. Because of the seriousness of missing a diagnosis of cancer, most urologists have a low threshold for working up any significant hematuria.
SIGNIFICANT HEMATURIA
As few as three red blood cells (RBCs) per hpf (high power field) in a voided specimen from an adult male is considered significant. RBCs found in the urine can be differentiated into two types based on origin: epithelial RBCs and glomerular RBCs.
Epithelial RBCs are regular, with smooth, rounded, or crenated membranes and an even hemoglobin distribution. As few as one epithelial RBC per hpf is abnormal and is considered a sign of urologic disease.
Glomerular RBCs are dysmorphic with irregular shapes and cell membranes and minimal or uneven hemoglobin distribution. More than 1,000,000 RBCs normally escape from the glomerular capillaries into the urine every 24 hours. The cells become dysmorphic because of the osmotic stresses experienced during passage through the nephron. A level of greater than two RBCs per hpf is abnormal and suggests glomerular disease.
DIFFERENTIAL DIAGNOSIS
Qualifying the type of hematuria and any associated symptoms can narrow the differential diagnosis of hematuria. Bright red gross, or macroscopic, hematuria is usually of lower urinary tract origin, whereas renal parenchymal bleeding is usually smoky,
hazy, or reddish-brown owing to the formation of acid hematin in urine of low pH. Proteinuria out of proportion to the degree of hematuria (i.e., >2+ protein on dipstick or >1 g/24-hour urine with microscopic hematuria) suggests a renal parenchymal origin (e.g., glomerulonephritis). An active urine sediment (e.g., red cell casts or granular casts) also suggests a renal parenchymal origin. Medical hematuria (e.g., renal parenchymal disease excluding tumors) is suggested by the presence of glomerular RBCs, an active urinary sediment, and significant proteinuria. Surgical hematuria is suggested by epithelial RBCs, no casts, and minimal proteinuria.
hazy, or reddish-brown owing to the formation of acid hematin in urine of low pH. Proteinuria out of proportion to the degree of hematuria (i.e., >2+ protein on dipstick or >1 g/24-hour urine with microscopic hematuria) suggests a renal parenchymal origin (e.g., glomerulonephritis). An active urine sediment (e.g., red cell casts or granular casts) also suggests a renal parenchymal origin. Medical hematuria (e.g., renal parenchymal disease excluding tumors) is suggested by the presence of glomerular RBCs, an active urinary sediment, and significant proteinuria. Surgical hematuria is suggested by epithelial RBCs, no casts, and minimal proteinuria.
Major Diagnosis Groups
Cancer
Infection
Stones
Benign prostatic hyperplasia
Renal parenchymal lesions
Trauma
Benign idiopathic hematuria
WORKUP
History
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