Value of urinary erythrocyte morphology in assessment of symptomless microhaematuria.

To assess the value of microscopic analysis of urinary erythrocyte morphology as the initial step in the investigation of patients with isolated symptomless microhaematuria, 316 consecutive patients were grouped according to whether they excreted eumorphic or mixed forms of erythrocytes or only dysmorphic forms. The former group was investigated fully, and urological disease was found in 85% of 123 patients. The 192 patients with exclusively dysmorphic erythrocytes in their urine and normal renal function (benign renal microhaematuria) were assigned to annual follow-up examinations of urinary red cell morphology and renal function, and subjected to invasive diagnostic procedures when a change was noted. In only 2 of the 132 patients followed up for at least 2 years did a new disease develop; this was easily identified at one of the annual examinations. Microscopic analysis of urinary erythrocyte morphology is therefore an effective method for identifying patients with symptomless microhaematuria needing specific diagnostic investigation.