A cortisol test checks for cortisol levels. Your body responds to stress with the aid of the hormone cortisol which also controls blood pressure, metabolism, inflammation and blood sugar levels. Your adrenal glands, two little glands located above the kidneys produce cortisol. If you consistently take high doses of specific steroid medications like prednisone, high levels of cortisol might be a result. Medical diseases including Cushing's disease and Addison's disease can be identified with the aid of a cortisol test.