Cortisol, Serum (Morning Sample)
What is CORTISOL?
A cortisol test is done to measure the level of the hormone cortisol, a primary stress hormone which provides protective response to a perceived threat or danger. There are certain diseases, such as Addison’s disease and Cushing’s disease, which may affect the production of cortisol in the body.
This test is done to diagnose Cushing’s syndrome, Addison’s disease and to check the functioning of the adrenal gland.
The level of cortisol hormone rises and falls during the course of a day. These levels are highest in the early morning, drop slowly throughout the day reaching the lowest around midnight. Usually, the test involves drawing blood in the morning before 10 AM.
Why is CORTISOL done?
The Blood Cortisol Test is performed:
· 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 pituitary glands
What does CORTISOL Measure?
Cortisol is a hormone secreted by the adrenal glands that help in the metabolism of carbohydrates, fats, and proteins. It also plays a regulatory role in maintaining blood sugar levels, water balance of the body. It is also essential in the maintenance of a healthy immune system. Cortisol mainly remains bound to proteins, and 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 (sleeping/rotational pattern). These levels are highest in the early morning, drops slowly throughout the day reaching its lowest around midnight, and again rises 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 pituitary gland located just below the brain. Fall in the blood cortisol levels affects the production of Corticotropin-Releasing Hormone (CRH) from the hypothalamus. CRH stimulates the pituitary gland to secrete 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 it stops the secretion of CRH which generates from the hypothalamus. This, in turn, stops ACTH secretion from the pituitary, 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 in the blood:
· 6 to 8 a.m.: 10 to 20 µg/dL
· Around 4 p.m.: 3 to 10 µg/dL
· Around 12 a.m.: Less than 5 µg/dL
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.
Reference range may vary from lab to lab*
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)
Answers to Patient Concerns & Frequently Asked Questions (FAQs) about CORTISOL
Frequently Asked Questions about Cortisol, Serum (Morning Sample)