If patient w/ partial ai and pit tumor, while taking 20-30 mg hydrocortisone has cortisol of 45 and acth of 12, and when off hydrocortisone has cortisol of 10 and acth of 65, what would you conclude?

Measuring drug: When on Hydrocortisone a high cortisol level is likely the measure of the drug and not endogenous secretion. A morning cortisol of 10 ug/dl once weaned off is great but doesn't represent the ability to respond to physiologic stress. A lo/hi acth stim test or Insulin tolerance test will prove it, though 10 is an excellent morning cortisol.

Cross- reactivity: Hydrocortisone cross reacts with the blood test for cortisol. So the higher cortisol level when on therapy probably reflects the medication being present in the blood. Depending on the time of day done, the other lab results might be normal.