Dexamethasone testing in prison inmates.

Topical dexamethasone responsiveness was determined in a group of 56 volunteer prison inmates. Drops were administered to each volunteer four times daily, thus eliminating the factor of patient reliability in use of the medication. The findings fit closely a prevalence of 0.25 for the steroid responder gene in the general population. An increased prevalence of nontasters to phenylthiocarbamide was found in those more highly responsive to topical dexamethasone. Thyroid function, as measured by protein-bound iodine (PBI) determination, did not correlate with the topical corticosteroid response, probably because of high dietary iodide intake. Plasma cortisol suppression testing also failed to correlate with corticosteroid response. This was felt to be the result of concomitant diphenylhydantoin administration.