EVALUATION OF THE THREE HOUR METYRAPONE TEST IN ADULTS

Abstract

The prolonged metyrapone test is used to assess the hypothalamic‐pituitary‐adrenal axis. The dynamic responses of cortisol, ACTH and 11‐deoxycortisol over the 3 h of the single morning dose metyrapone test have been examined in fourteen normal adult subjects. In every case there was a rapid, sustained fall in cortisol, but the resultant ACTH responses were extremely variable and in two subjects did not exceed values obtained during the control studies. The rise in 11‐deoxycortisol was also variable and in several instances occurred without any significant elevation in ACTH. In these cases, the rise in 11‐deoxycortisol may be due to a normal level of production of steroids with a shift from cortisol to 11‐deoxycortisol induced by the metyrapone. Thus, the hypothalamic‐pituitary‐adrenal axis may not be adequately tested, and this together with the high incidence of unpleasant side effects, makes the 3 h oral metyrapone test unsatisfactory for routine use in adults.