To test whether your adrenal glands are able to respond to stimulation by the pituitary, the physician injects you with ACTH (pituitary hormone for cortisol) and checks your blood twice over the subsequent couple of hours to look for an increase in cortisol. However, if the adrenal glands are responsive (cortisol rises), the next step is to test whether the pituitary itself is responsive to stimulation by injecting the higher level stimulating factor of the hypothalamus.