An unusual case of hyponatremia causing rhabdomyolysis

Rhabdomyolysis is a clinical condition characterized by muscle necrosis and the release of intracellular muscle contents into systemic circulation there by leading to asymptomatic elevation of serum muscle enzymes, electrolyte imbalances, and acute renal failure. Hyponatremia is one of the commonest of electrolyte disorder. Hyponatremia causing rhabdomyolysis is very rare and mechanisms are unknown. A thirty four year old male patient with complaints of recurrent vomiting, severe myalgia, generalized weakness and altered sensorium without history of headache, seizures and other co-morbid medical conditions presented to our emergency room. Vitals and systemic examination was normal. Laboratory investigations suggested Syndrome of Inappropriate Anti Diuretic Hormone (SIADH) leading to Rhabdomyolysis and was confirmed with muscle biopsy. Double strength saline and tolvaptan was administered and patient was discharged with improvement in serum sodium and creatine kinase levels. After 4 weeks patient recovered completely and urine hemoglobin was negative with normal creatine kinase levels. Hyponatremia being a rare cause of rhabdomyolysis monitoring of renal function and serum creatine kinase during hyponatremia is warranted. Futher studies are required to uncover the mechanisms underlying hyponatremia causing rhabdomyolysis. Vaptans can play a significant role in in managing rhabdomyolysis induced by hyponatremia with other supportive treatment measures.