A 59-year-old man is recovering in hospital 2 weeks following a car accident in which he sustained head trauma. Laboratory studies show:
Serum sodium 120 mEq/L
Serum potassium 4.0 mEq/L
Serum calcium 10.0 mEq/L
Serum chloride 103 mEq/L
Serum bicarbonate 23 mEq/L
Urinary specific gravity 1.026
Which of the following is the most likely diagnosis?
