Tolvaptan therapy in hypervolemic hyponatremia secondary to heart failure

Case report A 50 y/o female, with a history of pulmonary artery HTN, SLE, seizure disorder, hypothyroidism and peptic ulcer disease presented to the ER with nausea, vomiting. She was approximately 10 lbs over dry weight. Physical exam positive for obesity, lethargy, decreased breath sounds, and bilateral lower extremities 3+ pitting edema. Labs: serum Na 121 mmol/L, and K 2.4 mmol/L, serum osmolality 250 mOsm/L, urine osmolality 369 mOsm/L, and urine Na <10 mmol/L, Cortisol 3.0μg/dL (on prednisone for SLE), and TSH 1.37 uIU/ml. Stable vitals. Initially started on fluid restriction and salt tablets followed by aggressive diuresis. However, no improvement despite being approximately net negative 18L of urine output. Demeclocycline was started as tolvaptan was unavailable. Na showed no improvement. Nephrology was consulted and tolvaptan initiated. Na improved to 129 mmol/L by discharge with marked improvement in nausea and lethargy. She continued tolvaptan after discharge. One week later, serum Na had trended up to 135 mmol/L Hyponatremia (serum Na <135 mmol/L) has high mortality rates with inpatient mortality as high as 50% in pts with Na <120 mmol/L. Symptoms include nausea, vomiting, and severe neurological dysfunction leading to respiratory arrest. Mechanisms related to ADH, make the V2 receptor a good therapeutic target. Volume status should be assessed. Hypervolemic hyponatremia can be seen in heart failure (HF) and is an independent predictor of mortality, HF hospitalization, and death (ESCAPE trial). HF patients presenting with hypervolemic hyponatremia can be candidates for vaptan therapy if they do not respond to diuresis and fluid/salt restriction. It is important to note in this case improvement in serum Na was noted with tolvaptan. However, studies in hypervolemic hyponatremia cases did not show improved mortality or morbidity effects long term (EVEREST trial). Therapy is limited to 30 days per the FDA, liver function must be monitored. Attention must be given to avoid rapid overcorrection of serum Na. This case highlights the significance of using vaptan therapy in hypervolemic hyponatremic patients who are refractory to diuresis.