A Late Presentation of Substance-related Rhabdomyolysis with Normal Serum Creatine Kinase Levels and Complicated with Acute Tubular Necrosis.

Substance abusers are at increased risk of acute kidney injury (AKI) compared to the general population due to nontraumatic rhabdomyolysis. The primary target of these nephrotoxic agents is the tubulointerstitial compartment and the most frequent findings on biopsy are consistent with acute tubular necrosis (ATN) and acute interstitial nephritis. We present a rare case of an intravenous cocaine and heroin abuser who presented with recent onset oliguria, hematuria, and reduced peroral intake. The urine dipstick testing showed guaiac positivity but no red blood cells on microscopy. The blood workup showed elevated serum creatinine and urea levels but normal creatinine kinase (CK) level. Renal biopsy showed tubular epithelial cell necrosis and positive immunoperoxidase staining for myoglobin pigment casts in renal tubules. The diagnosis of rhabdomyolysis-associated ATN secondary to substance abuse was suggested. However, normal serum CK levels as well as urine drug panel supported the delayed presentation of rhabdomyolysis complicated with ATN. The patient returned to normal health with no residual kidney dysfunction after undergoing temporary hemofiltration.