A suspected case of hyponatraemia induced rhabdomyolysis: a case report

BACKGROUND: Hyponatraemia is a documented but under-recognised cause of rhabdomyolysis, with the contrasting treatment strategies for the two conditions posing a unique challenge. Balancing the need for aggressive fluid replacement for the treatment of rhabdomyolysis, with the risk of rapidly correcting hyponatraemia is imperative. CASE PRESENTATION: A 52-year-old gentleman with a background of HIV infection and hypertension presented with seizures following methamphetamine use, acute water intoxication, and thiazide use. He was found to have severe hyponatraemia, and following initial correction with hypertonic saline, was commenced on a fluid restriction. After two days he developed abdominal wall and thigh pain, along with oliguria. Laboratory data demonstrated markedly elevated creatine kinase levels and deteriorating renal function. A diagnosis of rhabdomyolysis and severe acute kidney injury was made and aggressive fluid replacement commenced, leading to full resolution of the hyponatraemia, rhabdomyolysis and acute kidney injury. CONCLUSION: Hyponatraemia-induced rhabdomyolysis is rare but can cause significant morbidity and mortality if left untreated. Physicians should consider measuring creatine kinase levels in all patients presenting with severe hyponatraemia, particularly in the presence of other risk factors for rhabdomyolysis. Fluid replacement strategies must be considered in relation to the relative onset and risk of over-correcting hyponatraemia.