Extreme correction of hyponatremia in a patient treated with intravenous conivaptan

Intravenous administration of conivaptan, an arginine vasopressin (AVP) receptor antagonist, has been demonstrated to be a safe and effective therapy for euvolemic and hypervolemic hyponatremia. In this case report, we report an extremely rapid correction of serum sodium with a typical dosing regimen of conivaptan. The patient was a 24 year woman who presented with nausea and vomiting, and was found on imaging to have two intracranial tumors, one of which was a large pituitary macroadenoma. Her serum sodium declined to 121 mmol/L and intravenous conivaptan therapy was started. After approximately 25 mg of conivaptan, her sodium increased 16 mmol/L over 8.5 hours. Fortunately, in this case, this correction was well tolerated, and the patient experienced no adverse effects of such a dramatic correction of serum sodium. Despite the good clinical result in this case, it should serve as a warning regarding the use of conivaptan, that although a gradual steady improvement in serum sodium can be expected in the majority of patients, more extreme corrections can be inadvertently achieved with even moderate doses. Thus, the exact clinical situation should be taken into consideration, especially in cases of subacute to chronic hyponatremia, where such an extreme correction could lead to neurologic devastation.