A cortisol test, also called a cortisol level, is a blood test that measures the amount of cortisol in your system. Cortisol is a steroid hormone that's produced by the adrenal cortex; cortisol is released under stressful conditions in reaction to ACTH, a hormone produced by the pituitary gland. Your doctor performs a cortisol test to evaluate how efficiently your pituitary and adrenal glands are working.
Performing the Test
According to the National Institutes of Health, a cortisol test uses blood drawn from either the inside of your elbow or the back of your hand. Before drawing any blood, your doctor uses an antiseptic wipe to clean the area. An elastic band may be put around your upper arm to help more blood pool in your veins. A needle is inserted in your vein, and blood is collected into an airtight vial. However, according to the American Association for Clinical Chemistry, urine and saliva can be used to test excess cortisol levels as an alternative to a blood test.
Interferences
Certain medications can result in altered levels of cortisol. Estrogen and synthetic glucocorticoids, such as prednisone and prednisolone, can increase cortisol measurements. Androgen and phenytoin, on the other hand, can lower cortisol measurements. In addition, the American Association for Clinical Chemistry states that pregnancy, illness, and physical and emotional stress can also increase cortisol levels.
Results
According to the National Institutes of Health, a normal value for a cortisol test done at 8 a.m. is 6mcg to 23mcg per deciliter. However, the National Institutes of Health notes that the normal value can vary, depending on which laboratory did the analysis. Abnormal results from a cortisol level can indicate a disorder. Higher-than-normal cortisol levels indicate an adrenal tumor, Cushing's syndrome or ectopic ACTH-producing tumors. Lower-than-normal cortisol levels indicate Addison's disease or hypopituitarism.
