Why it’s helpful to get a cortisol level test

Skeletal formula: Calvero. Design: BOOST Thyroid.

Skeletal formula: Calvero. Design: BOOST Thyroid.

Cortisol is a stress hormone produced by your adrenal glands (1). Cortisol affects many parts of your body—including your muscles and bones, heart and blood vessels, lungs, hormone-producing glands, and your brain (2).

Cortisol has lots of functions—controlling how you respond to stress, how your body fights infections, adjusting blood sugar levels, and regulating blood pressure (2, 3).

Cortisol and your thyroid

An underactive thyroid causes an increase in cortisol levels in your blood (4). Two of the most common conditions caused by cortisol are Cushing’s syndrome (too much cortisol) and Addison’s disease (too little cortisol).

When should you have a cortisol test?

Ask your doctor for a cortisol test if you have the following symptoms:

  • Obesity (especially around your abdomen)

  • Very high or very low blood pressure

  • High blood sugar

  • Skin that bruises easily and purple streaks on your stomach

  • Weak muscles

  • Irregular periods

  • Hirsutism (in females)

  • Fatigue

  • Abdominal pain

  • Nausea, vomiting, and diarrhea

  • Hair loss

What can affect cortisol test results?

Bacterial or viral infections, stress, and pregnancy can influence a cortisol test read-out (5-7).

Cortisol should be measured in the morning—around 8am—when levels are highest (1).

Cortisol lab values

A cortisol test can be done through blood samples, urine, or saliva. Cortisol has a circadian rhythm—levels are very low to undetectable at midnight, increase to a peak in the morning, and then slowly decline throughout the day (8-10).

Average cortisol levels at 8 A.M. are between 100–250 mg/mL (11).

Reducing cortisol levels

There are several physical and mental ways you can reduce your cortisol levels.

Activities including yoga (especially if you have depression-like symptoms) creating art, and spending time in green and natural environments are all proven to lower cortisol levels (12-14).

Mental training including perspective-taking (looking at a situation from a different point of view), as well as techniques that optimize expectations and/or provide beneficial distraction (noting ways to healthily manage stressful situations or writing to distract yourself from unnecessary stress) can also help keep cortisol levels low (15, 16).

Track your stress levels, cortisol blood values, and more in BOOST Thyroid.


  1. Lee DY, et al. Technical and clinical aspects of cortisol as a biochemical marker of chronic stress, 2015

  2. Yaribeygi H, et al. The impact of stress on body function: A review, 2017

  3. Hakamata Y, et al. Amygdala-centred functional connectivity affects daily cortisol concentrations: a putative link with anxiety, 2017

  4. Iranmanesh A, et al.Dynamics of 24-hour endogenous cortisol secretion and clearance in primary hypothyroidism assessed before and after partial thyroid hormone replacement, 1990

  5. Torpy DJ, et al. Value of free cortisol measurement in systemic infection, 2007

  6. LeWinn KZ, et al. Elevated maternal cortisol levels during pregnancy are associated with reduced childhood IQ, 2009

  7. Cay M, et al. Effect of increase in cortisol level due to stress in healthy young individuals on dynamic and static balance scores, 2018

  8. Debono M., Ghobadi C., Rostami-Hodjegan A., Huatan H., Campbell M.J., Newell-Price J., et al. (2009) Modified-release hydrocortisone to provide circadian cortisol profiles. 

  9. Krieger D.T., Allen W., Rizzo F., Krieger H.P. (1971) Characterization of the normal temporal pattern of plasma corticosteroid levels.

  10. Weitzman E.D., Fukushima D., Nogeire C., Roffwarg H., Gallagher T.F., Hellman L. (1971). Twenty-four hour pattern of the episodic secretion of cortisol in normal subjects.

  11. Mura G, et al. Quality of Life, Cortisol Blood Levels and Exercise in Older Adults: Results of a Randomized Controlled Trial, 2014

  12. Thirthalli J, et al. Cortisol and antidepressant effects of yoga, 2013

  13. Kaimal G, et al. Reduction of Cortisol Levels and Participants' Responses Following Art Making, 2016

  14. Ewert A, et al. Levels of Nature and Stress Response, 2018

  15. Engert V, et al. Specific reduction in cortisol stress reactivity after social but not attention-based mental training, 2017

  16. Salzmann S, et al. Optimizing expectations and distraction leads to lower cortisol levels after acute stress, 2018