Normal values for a short-time ACTH intravenous and intramuscular stimulation test in women in the reproductive age

Normal values in endocrine testing are the most important precondition for the recognition of disorders of the endocrine system. To establish a reference range for adrenocorticotropic hormone (ACTH) stimulation tests, an intravenous and intramuscular ACTH stimulation test was conducted in 29 female volunteers without hyperandrogenism. A total of 25 IU of ACTH were administered intravenously or intramuscularly and blood sampling was performed before, 1 h and 2 h after ACTH injection. The test was performed on days 3-5 of the menstrual cycle. The following steroid hormones were assessed in the serum: 17 alpha-hydroxyprogesterone, 17 alpha-hydroxypregnenolone, dehydroepiandrosterone, testosterone, free testosterone and 5 alpha-dihydrotestosterone. The normal range was defined by the interval between the 5th and 95th percentiles; additionally the 1st, 25th, 50th, 75th and 99th percentiles are reported. A significant increase of serum hormone levels after ACTH administration could be observed for the following hormones: cortisol, 17 alpha-hydroxyprogesterone, 17 alpha-hydroxypregnenolone and dehydroepiandrosterone. There was no rise after ACTH application for testosterone, 5 alpha-dihydrotestosterone and free testosterone. It could be shown for all hormones that there was no significant difference between the serum levels that were reached after intravenous and intramuscular ACTH injection. Neither could we find a significant difference in the relative increase of the serum hormones when stimulation values were related to basal values. Since in most studies with ACTH stimulation tests, only the serum values 1 h after ACTH application are measured, we investigated whether the measurement of steroid hormones 2 h after ACTH application gave further information. We could demonstrate that for most measured serum hormones the majority of the volunteers had the maximal response 2 h after ACTH application, no matter whether ACTH was injected intramuscularly or intravenously. As a conclusion, we recommend the measurement of the respective hormones not only 1 h but also 2 h after ACTH stimulation. Since there is no increase after ACTH stimulation for total testosterone, free testosterone and 5 alpha-dihydrotestosterone, it is sufficient to assess the basal values of these hormones. Excessive adrenal response is reflected by dehydroepiandrosterone, 17 alpha-hydroxyprogesterone, 17 alpha-hydroxypregnenolone and cortisol.