Endocrine Abstracts

JOINT465

We report on a male with severe hyponatremia secondary to congestive cardiac failure from dilated cardiomyopathy who was managed with fluid restriction, diuresis, and Tolvaptan before proceeding to emergency cardiac transplantation.

Case synopsis: This 54-year-old gentleman had a preceding history of the viral flu 2 months before coming in with progressive shortness of breath and swelling of his legs. He had seen a cardiologist 1 month before his attendance and an outpatient echocardiogram had revealed severely impaired left ventricular function (ejection fraction of less than 35%) he was commenced on diuretics along with Bisoprolol, spironolactone, and Ramipril. He subsequently presented to ED 2 weeks later with symptoms of progressive heart failure. Electrolyte estimation revealed severe hyponatremia (sodium of 121 mmol/l) and acute kidney injury. His serum osmolality was 262mmol/kg, urine osmolality 644mmol/kg, urine sodium of 23 mmol/l. Liver functions were deranged in keeping with hepatic congestion secondary to severe heart failure while thyroid and adrenal function were normal. Oral Bumetanide had worsened his sodium levels (sodium of 114mmol/l) and renal function with a further dropping in his urine sodium levels to 11 mmol/l, and an endocrine opinion was sought for his deteriorating sodium levels. Tolvaptan was introduced at 15 mg daily with strict monitoring of his renal function and fluid status. His sodium improved to 126 mmol/l over 2 days though he remained profoundly volume overloaded with clinical heart failure. Intravenous diuresis was commenced with stabilization of his renal function and the patient was transferred to the cardiac unit for close observation. He continued to receive regular tolvaptan with subsequent stabilization of his sodium levels to the low 120’s and improvement in his renal failure proving that he had cardiorenal syndrome which responded to judicious management of his heart failure. Given persistent very poor cardiac function with an ejection fraction of under 15%, the patient was transferred to a tertiary hospital following discussion, for emergency orthoptic cardiac transplantation with a good outcome.

Discussion: This case highlights the importance of managing significant hyponatremia with a multi-disciplinary approach. Persistent low urine sodium in the setting of ongoing diuretics in our patient with severe hyponatremia suggested diuretic unresponsive heart failure and increasing risk of mortality and a poor outcome hence the key factor in management involved the judicious use of Tolvaptan and diuretics in optimizing heart failure as a bridge to eventual cardiac transplantation.