Production of cortisol is controlled by the action of ACTH. ACTH is produced by the pituitary gland. This gland is controlled by the hypothalamus in the brain. If either the hypothalamus or pituitary gland is damaged, less ACTH is produced. This can lead to problems with the adrenal glands and reduced cortisol production.
This may be caused by:
A tumor of the pituitary gland or hypothalamus.
Past radiation of the hypothalamus or pituitary gland.
Past surgery to the pituitary gland.
Rare conditions such as hemochromatosis, sarcoidosis, or Sheehan’s syndrome (hypopituitarism). Sheehan’s syndrome is sometimes caused by severe blood loss after giving birth.
The symptoms of secondary adrenocortical insufficiency are similar to those of Addison’s disease. (But darkening of the skin and high levels of potassium in the blood are not present like they are in Addison’s disease.)
With secondary adrenocortical insufficiency, only cortisol is low. The adrenal glands can still make normal amounts of aldosterone. Symptoms include:
Fatigue and muscle weakness. These may get worse over time.
Weight loss. Profound weight loss is a prominent symptom.
Loss of appetite.
Diagnosis starts with a medical history and physical exam. If your doctor suspects adrenal insufficiency, he or she will check your blood cortisol and ACTH levels. You may have 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 2 days in a row. In most cases, your adrenal glands will make cortisol by the end of the second treatment. This is true even if you have problems with the pituitary gland or hypothalamus. 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 it turns out that you don’t need treatment, you can stop treatment after testing is complete.
CT scan or MRI can be used to see if there are signs of damage to the brain or pituitary gland (such as a tumor) that is causing adrenal failure.