Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 22-07: Rhabdomyolysis + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Associated with crush injuries to muscle, immobility, drug toxicities, and hypothermia Characterized by serum elevations in muscle enzymes, including creatinine kinase (CK), and marked electrolyte abnormalities Release of myoglobin leads to direct renal toxicity +++ General Considerations ++ Defined as a syndrome of acute skeletal muscle necrosis, leading to myoglobinuria and markedly elevated creatine kinase levels Can result from crush injuries, prolonged immobility, seizures, substance abuse (eg, cocaine), and medications The presence of compromised kidney and liver function, diabetes mellitus, and hypothyroidism increase the risk of rhabdomyolysis in patients taking statins + Clinical Findings Download Section PDF Listen +++ ++ Myalgias Weakness May be asymptomatic Use of statins is an important cause of rhabdomyolysis The cytochrome P450 liver enzymes metabolize all statins except for pravastatin and rosuvastatin The following medications block the action of cytochrome P450 and can increase the risk of rhabdomyolysis when used with statins (but no increased risk when used with pravastatin or rosuvastatin): Protease inhibitors Erythromycin Itraconazole Clarithromycin Diltiazem Verapamil The likelihood of rhabdomyolysis also increases when statins are used with niacin and fibric acids (gemfibrozil, clofibrate, and fenofibrate). + Diagnosis Download Section PDF Listen +++ ++ Serum CK > 20,000–50,000 international units/L Elevated serum levels of AST, ALT, and lactate dehydrogenase (due to release of these enzymes from skeletal muscle) The massive acute elevations of muscle enzymes peak quickly and usually resolve within days once the inciting injury has been removed Urine may appear dark Urinary dipstick test Positive for "blood" but without red blood cells on urinary sediment This false-positive result is due to detection of myoglobin Injured muscle cells release intracellular components, leading to electrolyte derangements, including Hyperkalemia Hyperphosphatemia Hyperuricemia Hypocalcemia + Treatment Download Section PDF Listen +++ ++ The mainstay of treatment is Aggressive volume repletion with 0.9% normal saline (i.e. > 4 L/day) Removal of offending agents if medications are thought to have caused the disorder Adjunctive treatments with mannitol and alkalinization of the urine have not been proven to change outcomes in human trials Early exogenous calcium administration for hypocalcemia is not recommended unless the patient is symptomatic or the level becomes exceedingly low in an unconscious patient + Outcomes Download Section PDF Listen +++ +++ Complications ++ Acute tubular necrosis due to the toxic effects of filtering excessive quantities of myoglobin, which can be exacerbated by volume depletion Distal tubular obstruction from pigmented casts and intrarenal vasoconstriction +++ Prognosis ++ Myopathic complications of statins usually resolve within several weeks of discontinuing the drug +++ When to Refer ++ Clinically meaningful rhabdomyolysis requires immediate attention and inpatient management, so affected patients should not be referred to outpatient nephrology consultation unless to follow up after a hospital admission +++ When to Admit ++ Patients whose serum CK levels are > 15,000–20,000 international units/L, or patients with AKI or electrolyte derangements, should be admitted for fluid repletion and serial monitoring of CK and electrolytes + References Download Section PDF Listen +++ + +Cervellin G et al. Non-traumatic rhabdomyolysis: background, laboratory features, and acute clinical management. Clin Biochem. 2017 Aug;50(12):656–62. [PubMed: 28235546] + +Long B et al. An evidence-based narrative review of the emergency department evaluation and management of rhabdomyolysis. Am J Emerg Med. 2019 Mar;37(3):518–23. [PubMed: 30630682] + +Panzio N et al. Molecular mechanisms and novel therapeutic approaches to rhabdomyolysis-induced acute kidney injury. Kidney Blood Press Res. 2015;40(5):520–32. [PubMed: 26512883]