Impending cardiac tamponade caused by salt supplement in a hyponatremic patient with chronic kidney disease.

We documented a hyponatremic patient who developed imminent cardiac tamponade upon oral salt supplement. A 72-year-old diabetic woman had hemorrhagic stroke; pericardial effusion; and chronic kidney disease, stage IV. She developed hyponatremia (serum sodium level, 125 mmol/L), compatible with the syndrome of inappropriate antidiuretic hormone, and received oral salt supplement 9 g/d for 4 days. Shortness of breathing and increasing heart rate ensued, and the echocardiography found accumulation of pericardial effusion with signs of impending cardiac tamponade. Pig-tail drainage through pericardiocentesis was done, and the vital signs were stabilized. We found the production of pericardial effusion increased from 100 to 220 mL/d after oral salt supplement at 3 g/d was reassumed. We discuss the relationship between serum sodium levels, the dose of salt supplement and the accumulation of pericardial effusion.