What does the presence of red blood cell casts in urine signify?

• A. Indicates glomerular pathology such as nephritic syndrome
• B. Indicates dehydration
• C. Indicates infection
• D. Indicates obstruction

Answer: (A)

Red blood cell casts indicate that red cells are leaking through damaged glomerular capillaries and becoming trapped in the tubular cast matrix. This reflects glomerular injury and inflammation, as seen in nephritic syndromes and acute glomerulonephritis. In this setting, you often see hematuria with red blood cell casts in the urine, sometimes with mild to moderate proteinuria and signs of renal dysfunction.

In contrast, dehydration typically shows concentrated urine without such casts, infections more often produce white blood cell casts or other signs of infection, and obstruction leads to different urinalysis patterns and sometimes crystals or hydronephrosis rather than RBC casts.