The adrenal glands are part of the endocrine system, which means that they make hormones. The adrenal glands are predominantly controlled by the pituitary, which is another gland in the endocrine system. The functionality of the adrenal glands can be compromised by tumors, damage to the glands themselves or problems with the pituitary. Testing of the adrenal glands usually focuses on assessing the levels of different hormones that the adrenal glands produce.
Significance
Tests can determine if the adrenal glands are overactive or underactive, as well as if the condition is caused by a problem with the adrenal glands themselves or some other disorder, such as a problem with the pituitary gland.
Detection
Adrenal hormones, LabTestsOnline explains, can be detected in the saliva, blood or the urine. Saliva makes for a very convenient but less accurate sample. The levels of adrenal hormones in urine can also be assessed, although typically a patient needs to provide a 24-hour urine sample (a collection of all urine expelled for 24 hours) for analysis. Adrenal function tests can also be done in concert with other blood testing.
Cortisol Measurement
Cortisol, according to MedlinePlus, is a commonly measured adrenal hormone because its levels are frequently altered as a result of adrenal problems. It has a natural ebb and flow throughout the day, with the blood levels being highest in the morning and lowest at night. For this reason, cortisol levels are commonly tested using the 24-hour urine samples, as these provide numbers independent of the ebb and flow. MedlinePlus notes that normal cortisol levels are between 10 and 100 mcg per 24-hour urine specimen.
Cortisol Test Types
If a patient has abnormally high or abnormally low levels of cortisol, tests can be done to determine if the cause of the abnormality is due to the adrenal glands or some other health problem. The ACTH stimulation test, MedlinePlus explains, involves measuring a patient's 24-hour cortisol levels before and after an injection of a hormone called ACTH. ACTH is produced by the pituitary and causes the adrenal glands to secrete additional cortisol. Patients with low cortisol levels that do not rise in response to ACTH likely have a problem with their adrenal glands. The dexamethasone suppression test is the opposite of ACTH stimulation; patients' cortisol levels are measured before and after the administration of dexamethasone. Dexamethasone inhibits adrenal production of cortisol.
Other Types
Adrenal abnormalities (such as an adrenal tumor) can be diagnosed using a CT or an MRI scan. If any growths are observed, a needle biopsy can provide a tissue sample of the tumor, which allows physicians to examine the tissue under a microscope to determine if it is cancerous.
