Estimation of prednisone intake in pemphigus vulgaris patients with the use of simple laboratory methods.

Prednisone is a widely used medication in dermatology, particularly in pemphigus patients. Simple objective laboratory methods are suggested for the evaluation of prednisone intake, taking advantage of the similar chemical structure of cortisol and prednisolone. A linear correlation was found between the dose of prednisone, above 40 mg/day, free urinary prednisolone, measured with an radioimmunoassay kit for cortisol that cross-reacts with prednisolone, and 17-hydroxycorticosteroids, measured by Metcalf's method. Approximately 9% of the prednisone administered was recovered as free prednisolone and about 40% as 17-hydroxycorticosteroids. It is suggested that these simple laboratory methods constitute a useful substitute for the more costly, sophisticated methods available at present for determining levels of prednisone and prednisolone.