Cortisol blood test
Quick answer: A cortisol test measures cortisol, the stress hormone made by the adrenal glands, which normally peaks in the morning and falls through the day. Doctors order it to look for too much cortisol (Cushing's syndrome) or too little (adrenal insufficiency); morning and afternoon samples show the daily rhythm.
- SampleBlood
- TakesAbout 5 minutes per sample
- Before the testCome at the exact time your doctor asks for; tell staff about steroid medicines or creams you use.
How the test is done
- 1You come at the time your doctor sets, often around 8 to 9 am
- 2You rest for a short while before the sample
- 3A needle draws blood from a vein
- 4A second sample may be taken later in the day to see the daily pattern
What your results can mean
Reading your report
Ranges depend on the time of day the sample was taken, so discuss your result with your doctor.
If the result is outside the usual range
A high level can be seen with Cushing's syndrome, stress, illness, pregnancy or steroid medicines. A low level can be seen with adrenal insufficiency, such as Addison's disease, or after stopping long-term steroids.
Who usually has this test
People with symptoms of too much cortisol, such as weight gain and stretch marks, or too little, such as tiredness, weight loss and low blood pressure.
Risks and aftercare
A small bruise is possible; if you feel faint, dizzy or very unwell, contact your doctor.
Names and options
Also called: serum cortisol, 8 am cortisol, 4 pm cortisol
Options
- 8 am
- 4 pm
- Random
Listed by the hospital as
- CORTISOL 4 PM
- CORTISOL 8AM
- CORTISOL, SERUM (RANDOM)
Questions about this test
Why does the timing of a cortisol test matter?
Cortisol is highest in the early morning and lowest late at night. Testing at a set time makes the result easier to read.
Can steroid medicines affect my cortisol?
Yes. Steroid tablets, inhalers, creams and injections can change the result. Tell your doctor, but do not stop steroids suddenly.
What is a dexamethasone suppression test?
It is a test where you take a steroid tablet the night before and cortisol is measured the next morning. It helps check for Cushing's syndrome.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.