Mariani and colleagues determined the etiology for asymptomatic, isolated hematuria in adults in 1,000 consecutive cases. The clinical applicability of RBC dysmorphism diagnostically is somewhat limited by the need for phase-contrast microscopy and a trained urine microscopist. If glomerulonephritis appears an unlikely diagnosis on the basis of clinical findings, attempts should be made to determine whether hematuria is transient or persistent by serial urinalyses. Transient hematuria, particularly in young persons, is quite common and rarely indicative of significant pathology. When present in patients older than 50 years, however, transient hematuria warrants a comprehensive evaluation to rule out malignancy.
Historical clues can provide key diagnostic information in the evaluation of hematuric patients.
Flank pain radiating to the groin may indicate the presence of urinary tract obstruction caused by stones or blood clots. Dysuria, urinary frequency, and urgency are consistent with an infectious source. A recent upper respiratory tract infection may trigger hematuric episodes when IgA nephropathy or postinfectious glomerulonephritis is present. Hematuria may develop spontaneously in patients receiving anticoagulants. Finally, intense exercise such as long-distance running can precipitate hematuria, as can prostatic enlargement.