Inappropriate secretion of antidiuretic hormone and mycoplasma pneumonia infection.

A patient with chronic bronchitis and acute respiratory failure due to mycoplasma pneumonia received excess parenteral fluid and developed hyponatremia associated with generalized seizures. The low serum osmolarity and elevated urine osmolarity were consistent with SIADH. Treatment with erythromycin and water restriction resulted in the complete recovery of her acute respiratory condition and return of the serum sodium and osmolarity values to normal.