Secondary adrenocortical insufficiency

Secondary adrenocortical insufficiency is a condition in which a deficiency of adrenocorticotropic hormone (ACTH) leads to insufficient cortisol production.

Production of cortisol is controlled by the action of ACTH produced by the pituitary gland. The pituitary gland is regulated by the hypothalamus in the brain. If either the hypothalamus or pituitary gland is damaged, less ACTH is produced, leading to underfunctioning of the adrenal glands and reduced cortisol production.

This may be caused by:

• A tumor of the pituitary gland or hypothalamus.
• Previous radiation of the hypothalamus or pituitary gland.
• Previous surgery to the pituitary gland.
• Rare conditions such as hemochromatosis, sarcoidosis, or Sheehan's syndrome (hypopituitarism). Sheehan's syndrome is occasionally caused by severe blood loss after delivering a baby.

The symptoms of secondary adrenocortical insufficiency are similar to those of Addison's disease, except that darkening of the skin (hyperpigmentation) and high levels of potassium in the blood are not present.

With secondary adrenocortical insufficiency, only cortisol is low. The adrenal glands can still make normal amounts of aldosterone. Symptoms include:

• Fatigue and muscle weakness that gradually become worse over time.
• Weight loss. Profound weight loss is a prominent symptom.
• Loss of appetite.

Diagnosis starts with a medical history and physical examination. If your doctor suspects adrenal insufficiency, he or she will check your blood cortisol and ACTH levels. Your doctor may recommend imaging tests of the adrenal glands, the pituitary gland, or the hypothalamus.

If your doctor suspects secondary adrenocortical insufficiency, you may get infusions of ACTH on two consecutive days. In most cases, even if you have problems with the pituitary or hypothalamus, your adrenal glands will make cortisol by the end of the second treatment. If possible, your doctor will treat the condition that is causing secondary adrenocortical insufficiency. Your doctor may start treatment during the testing if he or she thinks adrenal insufficiency is likely. If treatment is found to be unnecessary, it can be stopped after testing is complete.

Computed tomography (CT scan) or magnetic resonance imaging (MRI) can be used to see whether there is evidence of damage to the brain or pituitary gland (such as a tumor) that is causing adrenal failure.