Physiological dosing of exogenous ACTH.

We evaluated the ACTH and cortisol responses to several doses of exogenous ACTH, and compared these values to the physiologic responses obtained in normal subjects undergoing insulin-induced hypoglycaemia. We determined that a cosyntrophin dose of 0.2 micrograms/kg body weight produced both ACTH and cortisol levels indistinguishable from the 'physiologic' stress-induced values. Since this dose is approximately 4 per cent of the standard 250 micrograms dose employed in tests of adrenal function, our findings suggest a need for caution in the interpretation of such tests.