Cortisol Response to Adrenocorticotrophin (ACTH) in Acute Stress

Overview

Cortisol deficiency is diagnosed by the adrenocorticotrophin (ACTH) stimulation test. This test measures cortisol levels in the blood before and after giving an injection of ACTH. Currently, the results of this test can only be reliably interpreted when it is carried out on people in non-stressful situations. Frequently the test is carried out in hospitalized patients in stressful situations, giving results that are hard to interpret. Our study is to first do this test in a non-stressful situation, followed by a repeat test in a stressful situation, to compare the results and create a set of guidelines for interpreting the test when it is carried out in stressful situations.

This study proposes to provide the reference range of cortisol results when the ACTH stimulation test is done under stressful conditions. This important information is currently not available in the literature. To achieve this, we will perform the ACTH stimulation test in a cohort of patients who are booked for elective surgery. By choosing elective surgery patients, we afford ourselves the opportunity of performing the test once before surgery. The test is then repeated within 12 hours of surgery. The first test will be done on an out-patient basis under usual conditions (minimal stress) while the second will be done under intense physical stress. The 2 sets of results will be compared and the effect of stress on test results will be determined. For the sake of uniformity, we have chosen patients who are booked to undergo repair of an abdominal aortic aneurysm (AAA) as our study cohort. The ACTH stimulation is an important test that suffers from limitations resulting from lack of clear guidelines for the interpretation of results done under stressful conditions. This study will thus improve the usefulness of an important tool in the evaluation of the hypothalamic-pituitary-adrenal axis in stressed patients.