The two main causes of low cortisol levels are due to primary and secondary adrenal insufficiency.
Primary adrenal insufficiency, also known as Addison's disease, is caused by the destruction or malfunction of the adrenal glands. This can be due to an autoimmune disorder such as Addison's disease, a genetic disorder, or because of a tumor or metastasis. With primary adrenal insufficiency, the body cannot produce enough cortisol and the person can experience symptoms such as fatigue, nausea, weight loss, and low blood pressure.
Secondary adrenal insufficiency is caused by a problem with the pituitary gland, which is responsible for sending signals to the adrenal glands to produce cortisol. If the pituitary gland is not functioning properly, it won't send the necessary signals and the adrenal glands won't produce enough cortisol. Secondary adrenal insufficiency can be caused by a tumor, radiation therapy, or due to certain medications. Symptoms of this condition include fatigue, low blood pressure, and low blood sugar.
In both types of adrenal insufficiency, treatment typically includes hormone replacement therapy to restore cortisol levels. This therapy may be in the form of oral medications or injections that contain cortisol or corticosteroids. Depending on the cause of the adrenal insufficiency, other treatments may also be necessary.