A NEW FLUORIMETRIC METHOD OF PLASMA CORTISOL ASSAY WITH A STUDY OF PITUITARY—ADRENAL FUNCTION USING METYRAPONE (SU. 4885)

Abstract

SUMMARY To assay falling cortisol levels in the plasma during intravenous metyrapone infusion, a new spectrophoto-fluorimetric method has been devised. The advantages of this method are its ability to estimate low concentrations of cortisol, its precision, the small volumes of plasma required (1·0 ml.) and the rapidity with which results may be obtained (3–4 hr.). The metyrapone test has been applied to discover its value as a clinical test of pituitary—adrenal function following steroid therapy, before subjecting patients to the stress of surgery. Tests were made on seven normal subjects, and fourteen patients with ulcerative colitis of whom eight had received steroids previously. Three patients in the steroid-treated group and one who had not received steroids previously failed to show a normal response. When subjected to operation, all four showed the usual elevation of plasma cortisol during operative stress. None of those having a normal response to the metyrapone test failed to show a normal plasma cortisol elevation during operation. Metyrapone i.v. has therefore proved of uncertain value as a clinical test; the failure to respond in four cases did not prove to be an indication for the need for steroid therapy during surgery.