ABSTRACT
BACKGROUND: Pharmacological ACTH test provide information only about the ability of the adrenal gland to respond to unusual stimuli and may not reflect the daily cortisol secretion. There were some controversies in the diagnosis of mild adrenal insufficiency by using a pharmacological dose of ACTH. The purpose of the present study was to assess and compare the effect of low dose 1 pg ACTH and high dose 249 pg ACTH in the evaluation of adrenal function. The intravenous injection of a pharmacological dose(250 pg) of ACTH has been used as a standard test in the initial assessment of adrenal function. So we low dose ACTH to evaluate the adrenal function and compare the result of high dose ACTH. METHOD: Basal serum cortisol sampling was done at 2:00 p.m.. And after 1 pg ACTH iv bolus injection, cortisol sampling was done at 20, 30, 45 and 60 min respectively. On the next day same procedure was repeated at same time, but 249 mg ACTH was given instead of the low dose. Normal adrenal function was diagnosed with the criteria of stimulated serum cortisol concentration over 20 mg/dL. Total 65 patients took part in this study. Three hypopituitarism patients and one Addisons disease were included. Sixty-one patients had the history of glucocorticoid ingestion or had physical findings of cushingoid features with symptoms suggest the adrenal insufficiency. RESULTS: Sixteen patients showed normal response to both low dose and high dose ACTH. Thirty-six patients were not stimulated to both low dose and high dose ACTH. The remaining thirteen patients revealed normal response to high dose ACTH, but not to low dose ACTH. CONCLUSION: It appears that low dose ACTH stimulation test is more sensitive and specific than high dose ACTH and is capable of revealing mild adrenal insufficiency.