Nephrogenic diabetes insipidus and renal tubular acidosis secondary to foscarnet therapy.

Foscarnet is used as therapy of cytomegalovirus (CMV) infection in immunosuppressed subjects. We present a patient with human immunodeficiency virus infection under treatment with foscarnet for CMV retinitis who complained of thirst and polyuria. Laboratory data showed hypernatremia with increased plasma osmolality and metabolic hyperchloremic acidosis. A water deprivation test demonstrated a nephrogenic diabetes insipidus. Other laboratory studies, including urine pH, anion gap, titratable acidity, and bicarbonate, showed a distal tubular acidification defect. All abnormalities were transient, with recovery a few days after foscarnet withdrawal. No cases of renal acidosis, and only one case of nephrogenic diabetes insipidus, has been previously reported as a complication of foscarnet treatment. Our patient developed both nephrogenic diabetes insipidus and renal tubular acidosis with a temporal pattern that demonstrated a link between foscarnet therapy and these abnormalities.