Gross hematuria refers to the presence of frank blood in the urine and is more characteristic of lower urinary tract disease and/or bleeding diatheses than intrinsic renal disease (Table 46-3). Cyst rupture in polycystic kidney disease and postpharyngitic flares of IgA nephropathy are exceptions. Microscopic hematuria (>1-2 red blood cells [RBCs] per high-powered field), accompanied by proteinuria, hypertension, and an active urinary sediment (the “nephritic syndrome”) is most likely related to an inflammatory glomerulonephritis, classically poststreptococcal glomerulonephritis (Chap. 141. Renal Transplantation).

Free hemoglobin and myoglobin are detected by dipstick; a negative urinary sediment with strongly heme-positive dipstick is characteristic of either hemolysis or rhabdomyolysis, which can be differentiated by clinical history and laboratory testing. RBC casts are not a sensitive finding but when seen are highly specific for glomerulonephritis. Specificity of urinalysis can be enhanced by examining urine with a phase contrast microscope capable of detecting dysmorphic red cells (“acanthocytes”) associated with glomerular disease.

The approach to the pt with hematuria is shown in Fig. 46-3.