Physiological dosing of exogenous ACTH

Area of Science:

• Endocrinology
• Adrenal Function Testing

Background:

• Adrenal function tests typically use high doses of exogenous ACTH (cosyntropin).
• The physiological stress response involves endogenous ACTH and cortisol release.

Purpose of the Study:

• To compare the hormonal responses to low-dose cosyntropin with physiological stress-induced responses.
• To evaluate the adequacy of a reduced cosyntropin dose in stimulating adrenal function.

Main Methods:

• Administered various doses of exogenous ACTH (cosyntropin) to subjects.
• Measured ACTH and cortisol levels post-administration.
• Compared these levels to those obtained during insulin-induced hypoglycemia (a physiological stressor).

Main Results:

• A cosyntropin dose of 0.2 micrograms/kg body weight elicited ACTH and cortisol levels comparable to physiological stress.
• This effective dose is only about 4% of the standard 250 micrograms dose used in adrenal function tests.

Conclusions:

• The standard high-dose ACTH stimulation test may not be necessary for assessing adrenal reserve.
• A lower, more physiological dose of cosyntropin can effectively evaluate adrenal function.
• Caution is advised in interpreting results from standard high-dose adrenal function tests.