In primary adrenal insufficiency, what would the ACTH level typically be?

In primary adrenal insufficiency, the adrenal glands are unable to produce adequate amounts of steroid hormones, particularly cortisol. This deficiency leads to an increase in the secretion of adrenocorticotropic hormone (ACTH) from the pituitary gland. The pituitary gland senses the low levels of cortisol and responds by increasing production of ACTH in an attempt to stimulate the adrenal glands to produce more hormones. Therefore, in the context of primary adrenal insufficiency, ACTH levels are typically high due to this compensatory response.

This is distinct from other forms of adrenal insufficiency, such as secondary adrenal insufficiency, where the problem lies in the pituitary gland's production of ACTH, leading to low or normal ACTH levels. Understanding the physiological feedback loops in the endocrine system is crucial for interpreting hormone levels in different conditions.