Cortisol, or hydrocortisone, is a steroid hormone that is released into the bloodstream by the adrenal glands. The adrenal glands are located in the abdomen near the kidneys. Cortisol levels can vary during the course of the day, but highest levels are at about 6 to 8 a.m. and lowest levels are at about midnight. Lab testing for cortisol is usually done in the early morning. Normal circulating cortisol levels at this time are between 6 and 23 mcg/dL, according to MedLinePlus.
Cortisol Regulation
Cortisol is produced in the adrenal glands under the control of hypothalamic and pituitary hormones. The hypothalamus produces corticotropin-releasing hormone (CRH) to trigger the pituitary to produce adrenocorticotropic hormone (ACTH). ACTH travels in the bloodstream to the adrenal glands to stimulate cortisol production and release. Cortisol's function is to help increase blood sugar through liver production and to help in the release of glucose called gluconeogenesis, suppressing the immune system and aiding in the metabolism, or breakdown, of fats, proteins and carbohydrates.
How Cortisol Increases Glucose
Cortisol increases blood glucose levels by providing substrates for the liver to convert into blood sugar. Cortisol tells the body to breakdown structures to release fat and protein into the blood. The fat and protein is then converted into glucose through biochemical pathways in the liver.
Addison's Disease
Addison's disease is a disorder characterized by low activity of the adrenal gland in production of cortisol and aldosterone. The University of Maryland Medical Center states that 4 out of every 100,000 people have Addison's disease. Taking steroid medications, cancer, infection or other diseases can cause Addison's disease. Patients can develop very low blood sugar levels due to lack of cortisol and blood pressure due to retention of sodium and potassium. Symptoms include weakness, fatigue, weight loss, darkening of the skin, low blood pressure, low blood sugar and depression.
Cushing's Disease and Syndrome
Cushing's disease is a disorder of excessive secretion of ACTH from the pituitary gland. Cushing's syndrome is the clinical disorder of chronic exposure to excessive circulating levels of glucocorticoids. The condition leads to high blood pressure, high blood sugar, excessive hair growth, stretch marks, a round face, fatigue and changes to body fat deposition.
