A 55 year old man who presented to emergency room with black stool, coffee ground emesis and acute kidney injury. Serum creatinine is 17.4 mg/dL. Creatinine kinase (CK) is 9874 U/L. Serum albumin is 2.3 g/L. ANA is negative. C3 is normal. C4 is slightly high. Kappa to lambda free light ratio is normal. There is no monoclonal protein by immunofixation.  Urinalysis shows more than 600 protein, 18 white blood cells, and 3 RBCs. 

Terminology

•  Acute renal failure associated with pigmented tubular casts due to myoglobinuria 

Etiology/Pathogenesis

• Rhabdomyolysis (injury to skeletal muscle) releases myoglobin, which is iron-containing skeletal muscle protein

  • Trauma, drugs, toxins, inherited metabolic disorders, inflammatory myopathies

  • Predisposing factors include dehydration, fasting, hypo- or hyperthermia, hypoxia, hypokalemia

Clinical Issues

• Acute renal failure

• Elevated creatine kinase (CK-MM, often > 100,000 IU/L)

• Peaks within 48 hours after rhabdomyolysis with half-life of 48 hours

• Treatment is supportive with hydration

• Bile Cast Nephropathy

• Severe liver dysfunction, usually with jaundice

• Casts appear identical to myoglobin or hemoglobin

• Myeloma Cast Nephropathy

• Fractured casts, which are light chain restricted on immunofluorescence microscopy

• Acute (Ischemic or Toxic) Tubular Necrosis

• Pigmented casts from mitochondrial cytochromes lack myoglobin or hemoglobin

1- Natarajan, G, et al. Myoglobinuric renal failure after a wasp attack. Kidney Int. 2016; 89(3):725

2-  Zimmerman, JL, et al. Rhabdomyolysis. Chest. 2013; 144(3):1058–1065 

3- Zager, RA. Rhabdomyolysis and myohemoglobinuric acute renal failure. Kidney Int. 1996; 49(2):314–326.