Is the cosyntropin test redundant in the acutely ill patient suspected of adrenal insufficiency? A case report and literature review

Abstract

Relative adrenal insufficiency is an increasingly documented phenomenon in acute illness. Recognizing and treating such adrenal insufficiency has the potential to improve outcome. A post-cosyntropin cortisol value greater than 20 microg/dl has been recognized as consistent with normal adrenal function. While the cosyntropin test remains a superb test of primary adrenal failure, its utilityin the diagnosis of secondary adrenal failure is less clearly defined. In the setting of acute illness, a number of other criteria such as increment from basal serum cortisol have been used; however, the criteria for establishing adrenal insufficiency remains less clearly defined. We report a 44-year-old Caucasian female who presented with hypoglycemia and hypotension. The patient had a basal cortisol of 1.6 ug/dl and a peak serum cortisol of 23.3 ug/dl after 250 ug of cosyntropin. Despite this apparent normal response to cosyntropin, the patient responded to glucocorticoids with an improvement in her clinical status. Pituitary MRI revealed a 7-mm pituitary cyst. Pending the availability of free cortisol levels, it is prudent not to disregard low basal cortisol levels, even in the presence of a normal cosyntropin response. We recommend that clinicians managing acutely ill patients have a low threshold for initiating glucocorticoid replacement in the presence of hypoglycemia and shock regardless of the peak cortisol values.