Free Serum Cortisol icon

Free Serum Cortisol

Content Source: Health3 AG
Data Compiled From: Clinical laboratory standards & peer-reviewed research
Quality Assurance: Verified against multiple authoritative sources
Academic Sources: Adam, 2010; Brownlee, 2005; Barbé, 2013; Chen, 2015; Buford, 2008; Dal, 2020; Pagana, 2019; Bilezikian, 2007; Daimon, 2016; Cumming, 1983; Gandhi, 2023; Bodine, 2015; Andersen, 2015; Canalis, 1994; Luger, 2021; Kritikou, 2020; Chyun, 1984; Luger, 2021; Canalis, 1983; Butt, 2021
Last Verified: 2025-12-17
Our Content Standards & Medical Disclaimer

What is Free Serum Cortisol?

Cortisol, often referred to as the ""stress hormone,"" is produced by the adrenal glands and plays a crucial role in various body functions. It helps regulate metabolism, reduce inflammation, and assist with memory formulation. It's vital for maintaining blood sugar levels, regulating the body's salt and water balance, and managing stress response. Cortisol levels typically follow a diurnal rhythm – high in the morning and low in the evening. This should be considered when comparing your values. It helps the body respond to stress, but it's also important for many other bodily functions, including immune response and energy regulation.

Elevated cortisol levels over prolonged periods can lead to a variety of health issues, a condition often referred to as Cushing's syndrome. Symptoms of high cortisol levels include weight gain (particularly around the abdomen and face), thinning skin, easy bruising, fatigue, weakness, high blood pressure, mood swings, and increased thirst and urination. High cortisol can be due to various causes, including adrenal gland tumors, pituitary gland tumors, or long-term use of corticosteroid medications. Chronic stress can also contribute to persistently high cortisol levels, impacting overall health and well-being.

Conversely, low levels of cortisol, known as Addison's disease, can lead to symptoms such as fatigue, muscle weakness, weight loss, low blood pressure, mood changes, and darkening of the skin. This can be due to damage to the adrenal glands, autoimmune diseases, or certain medications that affect adrenal gland function. Both high and low cortisol levels can have significant health implications and usually require medical intervention for diagnosis and management.

To maintain healthy cortisol levels:

  • Practice stress management techniques such as mindfulness, deep breathing, meditation, or engaging in relaxing activities to help regulate cortisol levels.

  • Maintain a consistent sleep schedule and prioritize getting enough quality sleep, as sleep disturbances can affect cortisol rhythms.

  • Engage in regular physical activity, as exercise can help reduce stress and regulate cortisol levels. However, avoid excessive or intense exercise, which can temporarily elevate cortisol.

  • Eat a balanced diet rich in whole foods, and avoid excessive consumption of caffeine, alcohol, and processed foods, as these can impact cortisol levels.

  • If you suspect you have abnormal cortisol levels, consult with your healthcare provider for proper diagnosis and treatment.

​​​

Measurement Units

Free Serum Cortisol can be measured in: ng/L, nmol/L, µg/100mL, µg/dL, µg/L, µg/mL, µg%

Reference Ranges by Age and Gender

Reference ranges represent typical values for healthy individuals. Your healthcare provider must interpret your specific results.

Age Range Gender Unit Optimal Normal Source
All ages All genders µg/dL - 0.121 - 1.065 Pagana, 2019

Health Impact

Muscle Function​

A stress hormone that affects many bodily functions, including muscle metabolism. Chronic high levels of cortisol can lead to muscle breakdown and weakness. [Schakman, 2013][Bodine, 2015]

​
Premium

3 More Health Topics Available

Explore 3 additional health topics related to this biomarker in the Health3 app.

Download on App Store Get it on Google Play

Academic References

  1. Adam TC, Goran MI, Hasson RE, Lane CJ, Le KA, Mahurkar S, Toledo-Corral C, Ventura EE, and Weigensberg MJ. Cortisol is negatively associated with insulin sensitivity in overweight Latino youth (2010). J Clin Endocrinol Metab. DOI: 10.1210/jc.2010-0322
  2. Brownlee KK, Hackney AC, and Moore AW. Relationship between circulating cortisol and testosterone: influence of physical exercise (2005). J Sports Sci Med. View Source
  3. Barbé C, Kalista S, Loumaye A, Schakman O, and Thissen JP. Glucocorticoid-induced skeletal muscle atrophy (2013). Int J Biochem Cell Biol. DOI: 10.1016/j.biocel.2013.05.036
  4. Chen TC, Kuo T, McQueen A, and Wang JC. Regulation of Glucose Homeostasis by Glucocorticoids (2015). Adv Exp Med Biol. DOI: 10.1007/978-1-4939-2895-8_5
  5. Buford TW. Impact of DHEA(S) and cortisol on immune function in aging: a brief review. (2008). Appl Physiol Nutr Metab.
  6. Dal Z, Hackett RA, and Steptoe A. The relationship between sleep problems and cortisol in people with type 2 diabetes (2020). Psychoneuroendocrinology. DOI: 10.1016/j.psyneuen.2020.104688
  7. Pagana KD, Pagana TJ, and Pagana TN. Mosby’s Diagnostic & Laboratory Test Reference (2019). Mosby’s Diagnostic & Laboratory Test Reference.
  8. Bilezikian JP, Canalis E, Giustina A, and Mazziotti G. Glucocorticoid-induced osteoporosis: pathophysiology and therapy (2007). Osteoporos Int. DOI: 10.1007/s00198-007-0394-0
  9. Daimon M, Kageyama K, Kamba A, Matsuhashi Y, Matsuki K, Murakami H, Nakaji S, Otaka H, Sato E, Takahashi I, Takayasu S, Tanabe J, Terui K, Tokuda I, and Yanagimachi M. Association between Higher Serum Cortisol Levels and Decreased Insulin Secretion in a General Population (2016). PLoS One. DOI: 10.1371/journal.pone.0166077
  10. Cumming DC, Quigley ME, and Yen SS. Acute suppression of circulating testosterone levels by cortisol in men (1983). J Clin Endocrinol Metab. DOI: 10.1210/jcem-57-3-671
  11. Gandhi J, Sharma S, and Thau L. Physiology, Cortisol (2023). StatPearls. View Source
  12. Bodine SC and Furlow JD. Glucocorticoids and Skeletal Muscle (2015). Adv Exp Med Biol. DOI: 10.1007/978-1-4939-2895-8_7
  13. Andersen ML, Hirotsu C, and Tufik S. Interactions between sleep stress and metabolism: From physiological to pathological conditions (2015). Sleep Sci. DOI: 10.1016/j.slsci.2015.09.002
  14. Canalis E, Delany AM, and Dong Y. Mechanisms of glucocorticoid action in bone cells (1994). J Cell Biochem. DOI: 10.1002/jcb.240560304
  15. Luger A, Schernthaner-Reiter MH, Vila G, and Wolf P. The Interaction of Insulin and Pituitary Hormone Syndromes (2021). Front Endocrinol (Lausanne). DOI: 10.3389/fendo.2021.626427
  16. Kritikou I, Nicolaides NC, and Vgontzas AN. HPA Axis and Sleep (2020). View Source
  17. Chyun YS, Kream BE, and Raisz LG. Cortisol decreases bone formation by inhibiting periosteal cell proliferation (1984). Endocrinology. DOI: 10.1210/endo-114-2-477
  18. Luger A, Schernthaner-Reiter MH, Vila G, and Wolf P. The Interaction of Insulin and Pituitary Hormone Syndromes (2021). Front Endocrinol (Lausanne). DOI: 10.3389/fendo.2021.626427
  19. Canalis E. Effect of glucocorticoids on type I collagen synthesis alkaline phosphatase activity and deoxyribonucleic acid content in cultured rat calvariae (1983). Endocrinology. DOI: 10.1210/endo-112-3-931
  20. Butt Waleed, Liu Peter., O’Byrne Nora, and Yuen Fiona. Sleep and Circadian Regulation of Cortisol: A Short Review (2021). Curr Opin Endocr Metab Res. DOI: 10.1016/j.coemr.2021.03.011

Save this biomarker reference for your medical appointments

Track Free Serum Cortisol in Health3

Monitor your biomarkers, visualize trends, and share insights with your care team.

Download on the App Store Get it on Google Play