A 24-year-old woman's urinalysis is positive for blood on dipstick measurement. This is repeated twice between menstrual periods and it remains positive. Microscopic evaluation reveals RBCs, some of which are deformed and some in the form of casts. Which of the following is the most likely cause of the hematuria?: (A) urinary tract stones, (B) GN, (C) trauma, (D) benign renal tumor
Answer is B. The finding of red cell casts or dysmorphic red cells (best appreciated by phase microscopy) suggests the source of bleeding is glomerular in origin. Isolated hematuria is usually of urologic cause (eg, tumor, trauma, stone) but can also be of glomerular in origin.