What could be used to treat an underfunctioning adrenal cortex in Addison disease?

Answer is corticosteroids.

Explanation:

Addison disease regarded as a situation when the adrenal cortex is damaged. This usually occurs when the adrenal gland is mistakenly attacked by the body's immune system. It can also be explained as an endocrine disorder, which occurred, when the steroids produced by the adrenal gland are not enough.

It is known to cause sudden death in patients diagnosed at young age. Symptoms include weight loss, weakness and abdominal pain.