Syndrome of inappropriate antidiuretic hormone

Case history

A 76-year-old homeless man presents to the emergency department after police find him disoriented on the streets in late August. The patient gives little history, but admits to ongoing cough with productive sputum, night sweats/chills, and mild dyspnoea. He proceeds to suffer from a seizure. Vital signs demonstrate an elevated temperature at 38.7°C (101.7°F), a respiration rate of 26 breaths per minute, 94% oxygen saturation (on 3 L of O2), and pulse 87 bpm, with no evidence of orthostatic hypotension. Physical examination demonstrates a malnourished and dishevelled man in a postictal state. There is no sign of injury to the body. Crackles can be heard at the right lung base. Lab work demonstrates serum sodium of 120 mmol/L (120 mEq/L), serum creatinine of 88 micromol/L (1.0 mg/dL), and negative alcohol and toxicology screens. Chest x-ray demonstrates a large infiltrate in the right lower lung, consistent with pulmonary infection or abscess.