Reasons, Preparation & Procedure For Conducting a Cortisol Serum Test

Submitted on March 27, 2012

Cortisol serum or serum cortisol, as it is sometimes referred to, is a test to measure cortisol levels in the blood. Cortisol is a sterile hormone produced in the adrenal cortex. The hormone cortisol is produced in response to a hormone called ACTH, which is produced by the pituitary glands.

Reason Why It is Conducted

A serum cortisol test is taken to determine the functioning of the adrenal and pituitary glands. This helps in the diagnosis of several adrenal and pituitary gland related diseases. A normal result from this test would range from 6 to 23 mcg/dL (micrograms per deciliter). This is the accepted range although each laboratory may have a variation of a unit or two. Do note this is the cortisol level of a normal result as tested in the morning on or before 8 am.

A count higher than 23 mcg/dL would be an increased cortisol level which could be indicative of diseases like adrenal tumor, Ectopic, ATH tumors or Cushing's syndrome. A count of less than 6 mcg/dL could be indicative of conditions like hypopituitarism and Addison's disease.

This test is also conducted when a doctor suspects ectopic Cushing's syndrome, pituitary Cushing's syndrome or an acute adrenal crisis.


Cortisol serum test is a blood test, so preparation for this will mostly mean going off any prescription drug that could affect cortisol levels.

Drugs which cause an increase in cortisol levels include estrogens, synthetic glucocorticoids. Drugs which could result in decreased cortisol levels are androgens like phenytoin. Quite often it is expected that the patient come in early for tests.


This is a blood test, wherein blood is drawn usually from the vein inside the elbow or from the back of the hand. The vein area is cleaned with an antiseptic and an elastic band is wrapped tightly around the upper arm to exert more pressure and fill the vein with blood. This also helps to make the vein swell out prominently, making it easier to spot it. A needle is then inserted into the swollen vein and blood is collected into a tube or an airtight vial attached at the end of the needle.

As the needle is inserted and blood starts collecting, the band is removed from the arm. Once the vial is full, the needle is extracted and a piece of cotton will be placed on the area, and you or the person conducting the test will have to hold the cotton tightly on the vein area to stop any further bleeding.

Once the vial has been shut tight and labeled appropriately, you will be asked to remove the cotton or gauze and a tiny little plaster will be placed on it. In most cases, you will experience a small twinge like an ant bite when the needle is inserted and the area from where the blood is drawn might throb for a while after the test. But in all, it's not a painful process.

There are instances, however, when a person might feel a little woozy because of the loss of blood. In such cases, it's best to drink some citrus fluids after the blood test. Sweet lime, in particular is considered very effective in combating dizziness after a blood test.