The rapid low-dose (1 mu g) cosyntropin test in the immediate postoperative period: Results in elderly subjects after major abdominal surgery

Background. Recently the rapid low-dose (1 mu g) cosyntropin test has been found to be superior to the standard (250 mu g) rapid cosyntropin test for evaluating the hypothalamic-pituitary-adrenal axis. Because the 1-mu g test has not been studied in postoperative patients, we evaluated the test afte r major abdominal surgery. Methods. We performed rapid 1 mu g cosyntropin tests in 20 patients aged 65 years or older immediately and 24 hours after uncomplicated elective abdom inal surgery (group A) and in 10 patients who were suspected of having adre nal insufficiency after abdominal surgery (group B). Subsequently, 250 mu g of cosyntropin was infused over 8 hours on 2 successive days in group B pa tients. Results. Ninety-five percent of group A patients had normal rapid 1 mu g co syntropin test results immediately after surgery and 90% had normal test re sults 24 hours postoperatively. Six group B patients had abnormal rapid 1-m u g cosyntropin test results. Additional testing indicated primary adrenal insufficiency in 2 patients and central adrenal insufficiency in 1 patient; another patient probably had primary adrenal insufficiency and 2 patients appeared to be euadrenal. Four group B patients had normal adrenal function ; 1 probably had primary adrenal insufficiency. Conclusion. The rapid 1-mu g cosyntropin test accurately evaluated adrenal gland function in selected patients after uncomplicated surgery. The test, however, was difficult to interpret in unselected seriously ill postoperati ve patients. Therefore we recommend that postoperative patients with unexpl ained hypotension or other features suggestive of adrenal insufficiency who have random plasma cortisol levels less than 20 mu g/dL be treated with gl ucocorticoids and the hypothalamic-pituitary-adrenal axis be studied by sta ndard tests after recovery.