Diagnosis and management

The diagnosis of ACTH deficiency should be suspected when low plasma levels of morning cortisol are measured (a screening cortisol level collected at 8 AM that is 10 µg/dL or more is reassuring for ACTH sufficiency, whereas a value of 5 µg/dL or lower is suspicious for insufficiency).

Confirmation is necessary using dynamic testing such as the low-dose ACTH stimulation test.[93]

Because of the substantial risk of central adrenal insufficiency among survivors treated with cranial radiation doses exceeding 30 Gy to the hypothalamic-pituitary axis, endocrine monitoring with periodic dynamic testing as clinically indicated is recommended for this high-risk group.[43]

Patients with partial ACTH deficiency may have only subtle symptoms unless they become ill.[43]

Illness can disrupt these patients’ usual homeostasis and cause a more severe, prolonged, or complicated course than expected. As in complete ACTH deficiency, incomplete or unrecognized ACTH deficiency can be life-threatening during concurrent illness.

The treatment of ACTH deficiency relies on replacement with hydrocortisone, including stress dosing in situations of illness to adjust to the body’s physiologically increased need for glucocorticoids.[43]