Please list the possible aetiology, features of the presentation, and outline your principles of management of rhabdomyolysis.

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College Answer

Aetiology: consider trauma and muscle compression (including immobility), exertional rhabdomyolysis (eg. heat stroke, grand mal seizures), drugs and toxins (via coma/immobility, agitation/hyperthermia,  myotoxins eg. HMG-CoA reductase inhibitors,   myonecrosis secondary to non-depolarising neuromuscular blockers), infections, inflammatory myopathies (eg. polymyositis), electrolyte abnormalities (esp. hypokalaemia and hypophosphataemia), hyperthermia (eg. malignant hyperpyrexia and neuroleptic malignant syndrome), metabolic myopathies.

Presentation:  Consider  history  of exertion,  fitting,  drug  exposure  (including  illicit),  immobility, family history, and previous episodes.   Patient may complain of painful or weak muscles, and pigmented urine. Investigations reveal markedly elevated muscle enzymes (especially CK), acute oliguric renal failure, and electrolyte abnormalities (hyperkalaemia, hyperphosphataemia, hypocalcaemia, hyperuricaemia and metabolic acidosis).

Principles of management: consider general supportive care, adequate fluid resuscitation, forced alkaline diuresis (including mannitol), specific treatment of underlying cause (eg. dantrolene, phosphate replacement, cooling, removal of precipitants, treatment of infection, fasciotomies etc), and correction of electrolyte abnormalities.

Discussion

Somebody at the college loves rhabdomyolysis. This question is virtually identical to Question 16 from the first paper of 2008 and Question 4 from the first paper of 2004.  It also vaguely resembles Question 26.3 from the second paper of 2013.

It is delightful to have a fellowship exam question start with "Please". Basic courtesy goes a long way.