Rhabdomyolysis - Differential Diagnosis Framework and Management Summary Causes of Rhabdomyolysis: • Trauma: - Immobilization - Crush injury - Compartment syndrome - Electrical injury • Exertional: - Hyperthermia/Heat exhaustion, Heat injury, Heat stroke - Metabolic myopathies - Excess exertion/training - Seizures - Malignant hyperthermia - Neuroleptic malignant syndrome • Nontraumatic Nonexertional: - Electrolytes - Toxins - Drugs - Statins - ETOH - Infection - Viral (HIV, Influenza, TSS, Herpes, Coxsackie, etc) - Endocrine: Hypo/Hyperthyroidism - Autoimmune: Polymyositis/Dermatomyositis Clinical Features: • Triad of symptoms: - Muscle pain - Weakness - Dark urine • Other symptoms: - Malaise - Muscle swelling - Fever - Tachycardia - N/V - Abdominal pain Labs: • CPK 5X ULN • AST/ALT Elevation 4:1 ratio (AST declines > ALT) • AKI: BUN/Cr ↑ • Aldolase ↑ • LDH ↑ • Hyperkalemia • Hyperphosphatemia • Hypocalcemia/Late - Hypercalcemia • Hyperuricemia • Hyponatremia • HAGMA • Late complication: DIC • CPK - if doesn’t decline - suspect continued muscle injury or compartment syndrome • Myoglobinuria: UA positive for blood with no RBC’s, + myoglobin AKI Mechanism: 1. Shift of extracellular fluid into injured muscles - HYPOTENSION → renal vasoconstriction → decreased renal perfusion → renal ischemia 2. Cast formation: Renal tubular obstruction 3. Direct myoglobin nephrotoxicity to kidney tubular cells 4. Heme associated free radicals - oxidative injury Treatment: 1. Treatment of underlying disease 2. Prevent Prerenal azotemia: Isotonic fluid/Lactated ringers - Initial rate: 1-2 L/hour with goal urine output: 200 ml/hr 3. Monitor potassium and calcium several times per day until stable 4. Loop diuretics for fluid overload 5. Dialysis for severe hyperkalemia or ATN 6. Allopurinol for hyperuricemia if levels > 8 mg/dL #Rhabdomyolysis #Differential #Diagnosis #Management #causes #treatment #nephrology
