Evaluation of 3 hour metyrapone test in children and adolescents.

An evaluation of a new 3 h metyrapone test is presented. The test consists of one oral dose of metyrapone given at 08.00-09.00 hours, and determination of plasma deoxycortisol from a single capillary blood sample taken 3 h later. The test has been assessed in children and adolescents in conjunction with a 5 day metyrapone test, insulin test, vasopressin test, and ACTH test in forty-five reference subjects, in thirty-six hypopituitary subjects with normal or deficient ACTH secretion, in three subjects with primary adrenocortical disease and in ten subjects prior to and after pharmacological prednisone medication. During the first hour after metyrapone the plasma cortisol level decreased to almost the low level maintained for the rest of the 3 h period. The plasma deoxycortisol concentration was basally less than or equal to 35 nmol/l and increased continuously during the 3 h period to the mean level of 299 (95% confidence interval 133-669) nmol/l in the reference subjects. The new test proved to be as accurate as the insulin test in detecting ACTH deficiency. No significant rise was observed in the plasma somatotrophin (GH) level in those children who had a normal GH response to insulin hypoglycaemia.