Hyponatremia in patients with symptomatic pericardial effusion.

BACKGROUND Hyponatremia is related to cardiac tamponade in isolated case reports. However, the incidence of hyponatremia in patients with cardiac tamponade is still undetermined. METHODS In a tertiary referral medical center, patients who presented with cardiac tamponade necessitating evacuation of pericardial effusion were included. Medical records were reviewed for the diagnosis of effusion and the underlying disease in each patient. Serum sodium concentrations before and after evacuation of effusion were analyzed. RESULTS A total of 48 patients were identified during a 3-year period and 26 patients (54.2%) were found to have hyponatremia. The condition was mild (130-134 mEq/L) in eight; moderate (120-129 mEq/L) in 16; and severe (<120 mEq/L) in two patients. The frequency of hyponatremia was significantly higher in patients with malignancy-related rather than nonmalignancy-related cardiac tamponade (62.2% vs. 27.3%, p = 0.041). Nineteen patients had hyponatremia at presentation and had paired serum sodium concentrations measured after evacuation of pericardial effusion. The postevacuation serum sodium concentrations were significantly higher than the pre-evacuation levels in all patients (p < 0.001). CONCLUSION Hyponatremia is common in patients with cardiac tamponade. However, prompt management of pericardial effusion will result in spontaneous and rapid recovery from hyponatremia.