Hormones are an important part of the body because they affect several aspects of the body's function such as growth, development, blood pressure, fluid balance and immunity. Endocrine glands like the thyroid gland, pituitary gland, pancreas and the adrenal glands situated above each kidney, secrete hormones. Corticosteroids, mineralocorticoids, androgens and catecholamines are the classes of hormones secereted by the adrenal gland. When an imbalance of adrenal hormones is suspected, certain tests including blood tests are done.
ACTH Stimulation Testing
ACTH or cosyntropin is a hormone synthesized and released by the pituitary gland which is located in the brain. When ACTH is released into the bloodstream, it stimulates the adrenal glands to produce a steroid hormone called cortisol. The ACTH stimulation test is done to evaluate the adrenal glands ability to produce cortisol. Medline Plus states that this test is used when Addison's disease or adrenal insufficiency is suspected. They are both diseases where the adrenal glands produce low quantities of adrenal hormones. This test is done by first measuring the amount of cortisol in a patient's blood and then injecting the patient with ACTH. The patients cortisol levels are then measured again 60 minutes after ACTH administration. Increased levels of cortisol suggests normal adrenal functioning while little to no response may indicate a problem with the adrenal glands.
Dexamethasone Test
Dexamethasone is a synthetic—man made—steroid that is similar to cortisol. It is used during the dexamethasone test to determine if a patient has Cushing’s syndrom, a disease where the adrenal glands produce high levels of cortisol. Dexamethasone suppresses ACTH production which would result in low cortisol production. The American Association for Clinical Chemistry, reports that dexamethasone testing involves administering oral dexamethasone to a patient every 6 hours over a period 2 to 4 days. After this, a blood sample is collected to check how much cortisol it contains. A normal response would be decreased levels of cortisol as ACTH suppresses its production. An abnormal result would be increased blood levels of cortisol which may indicate Cushing’s disease.
Aldosterone and Plasma Renin Activity
Aldosterone is a minerocorticoid hormone secreted by the adrenal glands. It is responsible for retaining sodium in the body and excreting potassium. Mayo Clinic reports that primary aldosteronism is a condition where the adrenal glands release too much aldosterone, leading to increased sodium and decreased potassium in the blood. High blood sodium results in increased blood volume and hypertension. The aldesterone and plasma rennin activity tests are used to measure the amount of aldosterone and renin in the blood. Renin is an enzyme released by the kidneys that regulates blood pressure and stimulates the release of aldosterone. During this test, blood is collected from a patient after a period of lying down or being upright. High levels of aldosterone and low renin levels in the blood sample may indicate primary aldosteronism.
