Free cortisol blood test
Quick answer: This test measures the part of cortisol in your blood that is not bound to proteins and is active. Doctors may order it when total cortisol could be misleading, for example in pregnancy or with oestrogen-containing medicines.
- SampleBlood
- TakesAbout 5 minutes
- Before the testCome at the time your doctor asks for; tell staff about steroid medicines you use.
How the test is done
- 1You come at the time your doctor advises, often in the morning
- 2The skin over a vein is cleaned
- 3A needle draws blood into a tube
- 4The lab measures the unbound part of cortisol
What your results can mean
Reading your report
Ranges depend on the time of day, 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 or significant stress. A low level can be seen with adrenal insufficiency, even when total cortisol looks normal because of raised binding proteins.
Who usually has this test
People in whom total cortisol may be misleading, such as pregnant women, women taking oestrogen-containing medicines, and very ill people.
Risks and aftercare
You can resume your day as normal; mild bruising may occur.
Names and options
Also called: free cortisol
Listed by the hospital as
- CORTISOL (FREE), SERUM
Questions about this test
Why would my doctor order free cortisol instead of total cortisol?
Total cortisol includes cortisol bound to proteins. When these proteins are high or low, free cortisol gives a clearer picture.
Does birth control affect cortisol results?
Oestrogen-containing pills raise the protein that binds cortisol, which raises total cortisol. Free cortisol is less affected.
Is free cortisol the same as urine or saliva cortisol?
They are related, as urine and saliva tests also measure free cortisol, but the methods and uses differ.
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 →
Reception
Waiting area
IVF lab
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.