About Granular Casts
Granular casts are cylindrical protein structures formed within kidney tubules from cellular debris; their presence in the urine indicates active damage or inflammation within the kidney tubules themselves. They are seen in acute tubular necrosis (ATN) — kidney damage from toxins, severe dehydration, or reduced blood flow — as well as in chronic kidney disease and glomerulonephritis. While a few granular casts per low-power field can be a normal finding after intense exercise, their presence in the context of elevated creatinine or proteinuria is a significant finding requiring nephrology evaluation.