Clinical resistance to vasopressin. Detection of antibody by hemagglutination.

We describe a patient with hypothalamic diabetes insipidus who after 20 years became refractory to the effect of commercial vasopressin injection. Vasopressin antibodies were measured using a sensitive hemagglutination technique. Resistance was associated with a high titer of antibodies that disappeared once vasopressin therapy was withdrawn and the diabetes insipidus was controlled with chlorpropamide. Antibodies were also measured in four additional patients with diabetes insipidus while they were or were not receiving vasopressin. A patient who had received the drug for only two years already had a substantial titer of antibodies to vasopressin, but in this case the response to the hormone was not impaired.