When are peak levels of adrenocorticotropic hormone typically expected to occur?

Peak levels of adrenocorticotropic hormone (ACTH) are typically expected to occur from 6 AM to 9 AM. This pattern reflects the diurnal rhythm of cortisol production and related hormones, which are influenced by the body's internal clock and the sleep-wake cycle.

ACTH is produced by the anterior pituitary gland and stimulates the adrenal glands to release cortisol, particularly in the morning. This release coincides with the body's need for increased energy and responsiveness at the start of the day. As the day progresses, levels of both ACTH and cortisol gradually decrease, aligning with the body's metabolic and stress response requirements.

Understanding this timing is crucial in clinical settings, particularly when assessing adrenal function or diagnosing disorders related to the hypothalamic-pituitary-adrenal (HPA) axis, as well as when timing medication or evaluating diagnostic tests such as ACTH stimulation tests.