Decreased adrenal responsiveness in hypothermic patients

We have performed ACTH simulation tests in a total of 14 subjects who were hypothermic at the time of initial presentation. Plasma cortisol values were measured before and 1 h after an iv dose of 25 U synthetic ACTH. The cortisol response was depressed in these subjects, with a mean rise of 32% and an absolute mean rise of 5.0 microgra/dl. There appeared to be a temperature threshold effect, with only minimal responses observed below 32 C. A subgroup of 5 patients with sluggish responses to ACTH while hypothermic (mean cortisol rise, 12.5%) were retested after warming and responded normally (mean rise, 166%). Thus, ACTH stimulation tests may be misleading in the hypothermic patient and should be performed only after body temperature has returned to normal.