Summary
Purpose: To compare the sensitivity of ACTH and 11-deoxy-cortisol (comp. S) responses in the
short metyrapone test and the latter with the insulin hypoglycemia test.
Methods: Retrospective evaluation of 115 short metyrapone tests and comparison of 18 pairs
of metyrapone and insulin tests. 20 healthy controls and 95 patients with confirmed
pituitary disease were studied. All hormones were measured by sensitive radioimmunoassays.
Results: In patients with pituitary disease not requiring hydrocortisone Substitution (n =
70), the ACTH response in the metyrapone test was subnormal in 47 cases (< 33 pmol/L),
the comp. S response (< 200 nmol/L) in 21 cases only. Comparison of the relationship
between ACTH and comp. S with an ACTH-cortisol dose-response curve obtained in normal
subjects shows that subnormal ACTH responses after metyrapone in the range between
13 and 33 pmol/L still generate normal comp. S responses. The results of the metyrapone
test correlated significantly with those of the insulin test.
Conclusions: Measuring plasma ACTH in the scope of the metyrapone test makes the test more sensitive
to detect secondary adrenal insufficiency than with Steroid measurements alone. Results
of the metyrapone test correlate significantly with the cortisol response to insulin
hypoglycemia.
Key words
hypopituitarism - metyrapone - ACTH - Compound S
