Cortisol is a hormone produced in your adrenal glands, which sit on top of your kidneys. It performs functions that include maintenance of your blood sugar levels and blood pressure, as well as the regulation of fat, carbohydrate and protein metabolism. Cortisol deficiency can indicate inadequate pituitary gland function or an adrenal gland disorder called Addison's disease.
The Basics
Although cortisol output occurs in the adrenal glands, regulation of that output is controlled by the hypothalamus, in your brain, and your pituitary gland. The signal for cortisol production begins with the release of corticotropin-releasing hormone, or CRH, in your hypothalamus. In response to CRH, your pituitary gland releases adrenocorticotrpin, or ACTH. In turn, ACTH triggers cortisol secretion in your adrenals.
Addison's Disease
Damage to your adrenal glands can trigger Addison's disease, also called primary adrenal insufficiency. In addition to cortisol deficiency, individuals with Addison's may develop a deficiency of a second important adrenal hormone called aldosterone. If you develop Addison's disease, you will likely experience the gradual onset of symptoms that include appetite loss, deepening, persistent fatigue, unexplained weight loss and muscle weakness. You may also develop low blood sugar, diarrhea, nausea, vomiting, depression, irritability, dizziness, fainting and an unusual desire for salty foods. Women may experience significant menstrual abnormalities.
Hypopituitarism
Cortisol deficiency may also arise as a result of insufficient production of ACTH in your pituitary gland, according to the U.S. National Library of Medicine's Medline Plus. Typically, this underproduction occurs as part of a larger syndrome called hypopituitarism, which also involves reduced pituitary output of hormones such as growth hormone, thyroid-stimulating hormone, oxytocin, prolactin and follicle-stimulating hormone. Potential symptoms of hypopituitarism include fatigue, headaches, abdominal pain, diminished appetite, low blood pressure, cold sensitivity, weight loss, loss of body hair, weakness and vision disturbances.
Underlying Causes
Roughly 80 percent of Addison's-related adrenal gland damage occurs when your immune system mistakenly attacks your adrenals, explains the National Endocrine and Metabolic Diseases Information Service. Disorders that trigger this faulty autoimmune response include polyendocrine deficiency syndrome and Schmidt's syndrome. You may also acquire adrenal gland damage from tuberculosis, genetic defects, cancer and chronic AIDS-related or fungal infections. Medline Plus lists potential causes of hypopituitarism that include head trauma, exposure to radiation, stroke, brain surgery, brain infections and tumors of your pituitary gland or hypothalamus, as well as tumors elsewhere in your brain.
Diagnosis and Treatment
Your doctor can begin diagnosing cortisol deficiency with simple blood or urine tests. If preliminary tests indicate a deficiency, your doctor may perform an ACTH stimulation test. In this procedure, your blood levels of cortisol are measured before and after an injection of synthetic ACTH. Limited increases in cortisol after this injection can confirm a deficiency. Your doctor can treat a deficiency with oral doses of synthetic cortisol-like compounds such as prednisone, dexamethasone and hydrocortisone.
