What is Cortisol?
Cortisol is a hormone secreted by the adrenal glands. Cortisol regulates nutrient metabolism. It also helps the body to maintain blood glucose and water balance, and a healthy immune system. Most of the cortisol in the blood remains bound to proteins, and only a small portion remains free and biologically active. The Blood Cortisol Test measures the total amount of cortisol hormone in the blood.
Why is Cortisol done?
· To diagnose Cushing’s syndrome caused due to high cortisol levels
· To diagnose Addison’s disease
· To detect and diagnose conditions of the adrenal glands or the pituitary glands
What does Cortisol Measure?
The Cortisol Test measures the total amount of cortisol hormone in the blood. Cortisol is a hormone secreted by the adrenal glands that helps in the metabolism of carbohydrates, fats, and proteins. It also plays a regulatory role in maintaining the blood sugar levels, water balance of the body. Cortisol also helps the body maintain a healthy immune system. Most of the cortisol found in the body is bound to proteins, only a small portion remains free and metabolically active.
Level of cortisol hormone rises and falls during the course of a day following a diurnal pattern. Cortisol levels reach highest in the early morning, drop slowly throughout the day reaching its lowest around midnight, and again increases slowly through the night to reach its highest early next morning. This diurnal pattern of cortisol secretion is maintained by the hypothalamus in the brain and the pituitary gland located just below the brain. Fall in the blood cortisol levels stimulates the production of Corticotropin Releasing Hormone (CRH) from the hypothalamus. CRH stimulates the pituitary gland to secrete the Adrenocorticotropic Hormone (ACTH), which in turn stimulates the production of cortisol from the adrenal glands to increase cortisol levels in the blood. Cortisol levels are regulated by a feedback mechanism. When cortisol levels rise to the required levels, CRH secretion from hypothalamus is stopped. This in turn stops ACTH secretion from the pituitary gland, thereby stopping cortisol secretion from the adrenal glands. Symptoms associated with increased or decreased levels of cortisol hormone appear when this feedback mechanism is disturbed due to diseases or lifestyle.
Interpreting Cortisol results
Normal cortisol levels may vary among individuals. Increased or decreased cortisol levels can be assessed only if the cortisol level in blood does not follow the diurnal pattern, as it should.
Cortisol levels may fall outside the normal range for the time of day due to diseases or due to lifestyle factors such as irregular sleeping times.
Causes of increased cortisol levels:
· Long term treatment with glucocorticosteroid hormones like prednisone, dexamethasone, etc.
· Pituitary tumors that increase ACTH production
· ACTH producing tumors in other parts of the body
· Adrenal tumors that increase cortisol secretion
· Congenital Adrenal Hyperplasia, a disease which causes excessive growth of adrenal gland cells
· Recent surgery, illness, injury, or sepsis
· CRH producing tumors in rare cases
Causes of decreased cortisol levels:
· Reduced cortisol production due to damage or diseases of the adrenal gland (primary adrenal insufficiency) like Addison’s disease
· Reduced ACTH production due to reduced activity of the pituitary gland or pituitary tumors (secondary adrenal insufficiency)