Cortisol
This page covers total cortisol in a morning blood sample. MedlinePlus gives 5 to 25 µg/dL at 8 a.m., and an Endocrine Society guideline reads a level below 5 as suggestive of adrenal insufficiency. Saliva, urine and stimulation tests measure different quantities. Results shift with time of day, oral estrogen and the assay used.
- Status
- A blood test ordered by a clinician and also sold direct to consumers by some US laboratories. FDA classifies cortisol test systems as class II devices [1].
- Measures
- The total cortisol in a morning blood sample. Cortisol is a steroid hormone made by the adrenal glands, and its level varies through the day [2].
- Also called
- cortisol, serum cortisol, cortisol blood test, total cortisol, cortisol total, morning cortisol, AM cortisol, 8 a.m. cortisol, plasma cortisol, hydrocortisone
- Tested for
- stress, fatigue, adrenal fatigue, adrenal insufficiency, Addison disease, Cushing syndrome, weight gain, sleep problems, coming off steroid medicines
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Linked in research0
None sourced yet.
Reported risks0
No risks sourced yet.
Reference ranges
Each range is the one its source published, in µg/dL. Also reported in nmol/L. Where sources differ, each is shown.
US National Library of Medicine, MedlinePlus
A blood sample taken at 8 in the morning · [2]
| Range | What the source calls it |
|---|---|
| below 5 µg/dL | No name given |
| 5 to 25 µg/dL | "normal" |
| above 25 µg/dL | No name given |
Printed as 5 to 25 mcg/dL or 138 to 690 nmol/L. MedlinePlus states that normal values depend on the time of day and the clinical context, that ranges may vary slightly among laboratories, and that the expected result can be outside this range when the sample is part of a cosyntropin stimulation test or a dexamethasone suppression test. It names no assay [2].
Endocrine Society guideline on primary adrenal insufficiency, 2016
People with symptoms or signs of adrenal insufficiency who are not taking glucocorticoids, sample drawn between 6 and 10 in the morning · [3]
| Range | What the source calls it |
|---|---|
| below 5 µg/dL | "suggestive of adrenal insufficiency" |
| 5 or above µg/dL | No name given |
Printed as below 140 nmol/L (5 µg/dL). The guideline suggests it, together with the ACTH level, as a preliminary test when a corticotropin stimulation test is not feasible, until confirmatory testing is available. It states that the cut point is not to be used for community-based screening and that the figure depends on the assay. It gives no morning level that rules adrenal insufficiency out, noting that studies have argued for levels from above 285 nmol/L (10.3 µg/dL) to above 480 nmol/L (17 µg/dL), so this block does not classify results of 5 or above any further. It notes that 5 µg/dL sits at or near the lower limit of 4.1 to 4.7 µg/dL found in reference populations with contemporary assays [3].
European Society of Endocrinology and Endocrine Society guideline on glucocorticoid-induced adrenal insufficiency, 2024
People coming off long-term glucocorticoid therapy, sample drawn between 8 and 9 in the morning at least 24 hours after the last dose · [4]
| Range | What the source calls it |
|---|---|
| below 5 µg/dL | No name given |
| 5 to 10 µg/dL | "indeterminate" |
| above 10 µg/dL | "recovery of the HPA axis" |
Printed as 150 nmol/L or 5 µg/dL and 300 nmol/L or 10 µg/dL. The guideline states that these are rounded, not exact conversions, and that the value is to be read as a continuum, with higher values more indicative of recovery of the hypothalamic-pituitary-adrenal (HPA) axis. It describes people below 5 µg/dL as very likely to have persistent adrenal insufficiency, and states that between 5 and 10 µg/dL recovery is possible and dynamic testing can be considered. The cut points were set for people taking glucocorticoids, not for the general population [4].
What has been shown to move it
Shown to lower it2
Cortisol
Shown to lower cortisol by about 1.2 µg/dL against placebo in adults, though perceived stress did not change in the same review.
A review of 23 trials of standardized root extract in healthy adults reported consistent cortisol reductions.
The numbers and sources
- Effect
- Across 7 trials, cortisol fell 1.16 µg/dL (95% CI -1.64 to -0.69) against placebo [4]. Across 23 placebo-controlled trials, cortisol fell (SMD -1.18, p < 0.04), with a possible dose-response by withanolide content [6]. A review of 23 trials of standardized root extract in healthy adults reported consistent cortisol reductions [7].
- Population
- Adults in RCTs of 2 weeks or more at 250 mg a day or more [4]. 1,706 adults in 23 RCTs [6]. 2,317 healthy adults [7].
- Sources
- [4], [6], [7]
- Caveats
- In the same review, cortisol fell while perceived stress did not change [4]. Cortisol is a lab marker, not a symptom. Two authors of [7] reported employment by companies, and two reported honoraria from supplement companies.
Stress and cortisol
Shown to lower salivary cortisol slightly in forest groups in one meta-analysis, and serum cortisol fell after forest visits in two small trials in men.
Compared with urban groups [1]; people with lower greenspace exposure [2]; the group sent to a city area [3]; the day before forest therapy, in the same men [4]
Across observational and intervention studies, greenspace exposure was linked to lower salivary cortisol (-0.05, 95% CI -0.07 to -0.04).
The numbers and sources
- Effect
- Salivary cortisol was lower in forest groups than urban groups after the intervention (MD -0.05 μg/dL, 95% CI -0.06 to -0.04, I² 88%), and also before it (MD -0.08 μg/dL). In all but two of 22 studies, cortisol was lower after forest time than in comparison groups or than before [1]. Across observational and intervention studies, greenspace exposure was linked to lower salivary cortisol (-0.05, 95% CI -0.07 to -0.04) [2]. After a two-night forest trip, serum cortisol was lower than in a group sent to a city, as were interleukin-6 and tumor necrosis factor alpha [3]. In middle-aged men with high-normal blood pressure, serum cortisol and urinary adrenaline were lower after forest therapy than the day before [4].
- Population
- 22 studies, 8 pooled [1]. 103 observational and 40 interventional studies [2]. 20 healthy male university students, randomized [3]. Middle-aged men with high-normal blood pressure [4].
- Sources
- [1], [2], [3], [4]
- Caveats
- The forest groups' cortisol was already lower before the visit, which the reviewers tie to anticipation and placebo effects [1]. Studies were short, small and mostly in Japan, and nobody can be blinded to a forest. The serum trials studied only men [3][4].
Studies disagree2
Stress hormones, blood pressure and immune cells after one session
Mixed results: a single session lowered blood pressure and heart rate in pooled trials, and cortisol fell in one small trial but not in pooled trials.
Compared with control conditions in randomized studies the source abstract does not describe [12]; light touch [18]
The numbers and sources
- Effect
- Single sessions reduced state anxiety, blood pressure and heart rate, and did not reduce cortisol [12]. In healthy adults, 45 minutes of Swedish massage produced a large drop in arginine vasopressin and a small drop in blood cortisol against light touch. Circulating lymphocytes rose (effect sizes 0.14 to 0.43) and stimulated cytokine production fell [18].
- Population
- 37 randomized studies [12]. Healthy adults aged 18 to 45 [18].
- Sources
- [12], [18]
- Caveats
- The trial calls its data preliminary, and these were changes over one session [18]. Lymphocyte counts in blood do not show fewer infections.
Cortisol
Small trials found mixed results: cortisol rose in older adults and did not rise in obese men.
How it compares with the reference method
Mixed results1
Morning cortisol against the ACTH stimulation test
Mixed results: morning levels below about 4 to 5 µg/dL or above about 11 to 13 predicted the stimulation test result, and levels in between did not.
The numbers and sources
- Compared with
- The 250 µg ACTH (cosyntropin) stimulation test
- Effect
- A 2024 guideline reviewed three studies in people who had taken glucocorticoids. In one, every patient with morning cortisol below 100 nmol/L (3.6 µg/dL) failed the stimulation test and every patient above 350 nmol/L (12.6 µg/dL) passed. In a second, a level of 336 nmol/L (12.1 µg/dL) or above was 100% specific for a normal test, and 124 nmol/L (4.5 µg/dL) or below was 100% sensitive for a failed one. In the third, a level above 310 nmol/L (11.2 µg/dL) excluded adrenal insufficiency with 98% sensitivity, and a level below 152 nmol/L (5.5 µg/dL) confirmed it with 97% specificity [4]. For the stimulation test itself, a peak below 500 nmol/L (18 µg/dL) had a sensitivity of 0.92 (95% CI 0.81 to 0.97) for primary adrenal insufficiency [3].
- Population
- Three studies of people on or after glucocorticoid therapy, two of which measured cortisol by immunoassay [4]. Five primary studies of primary adrenal insufficiency [3].
- Sources
- [4], [3]
- Caveats
- The guideline grades the evidence behind its morning cortisol recommendation at the lowest of its four levels [4]. The earlier guideline states that there is no evidence to support using a random cortisol to rule adrenal insufficiency out [3].
Did not match the reference method4
Immunoassays against mass spectrometry
One study found six routine cortisol assays varied considerably against a mass spectrometry reference method and overread samples from people taking prednisolone or metyrapone.
The numbers and sources
- Compared with
- A liquid chromatography tandem mass spectrometry candidate reference method
- Effect
- Six routine assays measured samples from men, nonpregnant women, pregnant women and people prescribed metyrapone or prednisolone. The authors report considerable variation between and within assays in the men and nonpregnant women. Four immunoassays read low in pregnancy, where cortisol-binding globulin was higher. All immunoassays overestimated cortisol in people taking metyrapone or prednisolone. A routine mass spectrometry assay aligned with the reference method in every group [8]. An Endocrine Society guideline notes that the lower reference limit 30 minutes after stimulation runs from 418 to 574 nmol/L (15.2 to 20.8 µg/dL) depending on the assay [3].
- Population
- Surplus serum samples grouped into five cohorts, measured by six routine assays in collaborating laboratories [8].
- Sources
- [8], [3]
- Caveats
- The abstract gives no figures for the size of the differences [8]. Guidelines state that cut points depend on the assay [3].
Oral estrogen and binding proteins
One study found total serum cortisol 67% higher in women taking oral estrogen than in women taking none, with similar salivary cortisol.
The numbers and sources
- Compared with
- Total serum cortisol in women not taking estrogen
- Effect
- Total serum cortisol was 660.9 nmol/L in women taking oral estrogen, 395.4 in women taking none and 334.7 in women using estrogen through the skin. Cortisol-binding globulin was 110.9 mg/L on oral estrogen against 49.0 in the women taking none. Salivary cortisol was similar in all three groups [9]. Guidelines state that oral estrogen and pregnancy raise cortisol-binding globulin and with it the measured cortisol, and that low albumin or binding globulin, as in nephrotic syndrome, advanced liver disease and prolonged critical illness, lowers it [3][4].
- Population
- 37 women with a mean age of 33: 14 taking oral estrogen, 8 using it through the skin and 15 taking none, sampled fasting between 8:30 and 9:30 a.m. [9].
- Sources
- [9], [3], [4]
- Caveats
- One cross-sectional study of 37 women. The blood test measures cortisol bound to protein together with the free hormone, so a change in binding protein moves the result [10].
Time of day
One study found cortisol peaked near 15.5 µg/dL around 8:30 a.m. and fell below 2 µg/dL around midnight.
The numbers and sources
- Compared with
- The same people's level at the morning peak
- Effect
- In 33 reference subjects whose daily cortisol rhythm was profiled, cortisol peaked at 15.5 µg/dL (95% reference range 11.7 to 20.6) at 8:32 a.m. and reached its lowest point, below 2 µg/dL (1.5 to 2.5), at 12:18 a.m. [11]. Guidelines time the sample to the morning: between 6 and 10 a.m. in one and between 8 and 9 a.m. in another. The second notes that morning cortisol can appear falsely low in people with a disrupted sleep cycle, such as night shift workers [3][4].
- Population
- 33 reference subjects in a cross-sectional study [11].
- Sources
- [11], [3], [4]
- Caveats
- One study of 33 people. A result from an afternoon or evening sample cannot be placed against the morning ranges on this page.
Saliva, urine, dexamethasone and stimulation tests
Not shown to stand in for other cortisol tests: Endocrine Society guidelines test for Cushing syndrome with urine, late-night saliva or dexamethasone suppression, each with its own cut point.
The numbers and sources
- Compared with
- 24-hour urinary free cortisol, late-night salivary cortisol, the 1 mg dexamethasone suppression test and the ACTH stimulation test
- Effect
- These tests measure different quantities, and their cut points do not apply to a morning blood level. For Cushing syndrome the guideline's criteria are urinary free cortisol above the normal range for the assay, late-night salivary cortisol above 145 ng/dL (4 nmol/L), and serum cortisol above 1.8 µg/dL (50 nmol/L) on the morning after 1 mg of dexamethasone. It recommends against using a random serum cortisol to test for Cushing syndrome. It reports sensitivity of 92% to 100% and specificity of 93% to 100% for late-night salivary cortisol, and sensitivity above 95% with specificity of 80% for the dexamethasone test at the 1.8 µg/dL cut point [10]. For adrenal insufficiency, the stimulation test reads the peak 30 or 60 minutes after an injection of corticotropin, and a peak below 500 nmol/L (18 µg/dL) indicates adrenal insufficiency [3].
- Population
- Evidence reviewed for two Endocrine Society clinical practice guidelines [10][3].
- Sources
- [10], [3]
- Caveats
- Guideline statements, with cut points that depend on the assay. The guideline notes that urinary free cortisol, unlike serum cortisol, is not affected by conditions and medicines that change binding protein [10].
What studies tie it to
Mixed results1
Cardiovascular disease
Mixed results: higher morning cortisol went with 18% more cardiovascular disease per standard deviation in pooled cohorts, while genetic studies found no clear effect on heart disease or stroke.
The numbers and sources
- Effect
- In two nested case-control studies, each standard deviation higher morning plasma cortisol had an odds ratio for new cardiovascular disease of 1.28 (95% CI 1.06 to 1.54), and in a meta-analysis with earlier prospective studies it was 1.18 (1.06 to 1.31). The same paper's genetic analysis gave 1.06 (0.98 to 1.15) [5]. A second genetic study found genetically predicted cortisol unrelated to ischemic heart disease (0.98, 0.93 to 1.03) or ischemic stroke (0.99, 0.91 to 1.08) [6]. A third found each standard deviation of genetically higher cortisol associated with more atrial fibrillation (1.20, 1.06 to 1.35), an association that disappeared after adjusting for genetically predicted blood pressure and waist size (0.99, 0.72 to 1.38) [7].
- Population
- 696 people with new cardiovascular disease and 6,680 controls in the pooled cohorts, and 122,737 coronary heart disease cases with 547,261 controls in the genetic analysis [5]. Genetic variants from a consortium of 12,597 people, applied to large outcome studies [6][7].
- Sources
- [5], [6], [7]
- Caveats
- The cohort finding is observational, and the genetic estimates disagree with one another. The genetic studies rest on a small number of variants [6][7].
Checked, no link found1
Type 2 diabetes in a genetic study
One genetic study found no association between genetically predicted cortisol and type 2 diabetes.
The numbers and sources
- Effect
- Genetically predicted cortisol, based on six variants, had an odds ratio for type 2 diabetes of 1.00 per unit of log-transformed cortisol (95% CI 0.96 to 1.04). It was also unrelated to adiposity, blood sugar traits, blood pressure and lipids. Genetically predicted diabetes was not associated with cortisol either [6].
- Population
- Six variants identified in 12,597 people, applied to genome-wide studies of type 2 diabetes [6].
- Sources
- [6]
- Caveats
- One genetic study, whose authors call for replication. Genetic estimates describe lifelong differences, not the effect of a change later in life [6].
Sources
- US Food and Drug Administration. 21 CFR 862.1205, Cortisol (hydrocortisone and hydroxycorticosterone) test system. Electronic Code of Federal Regulations. https://www.ecfr.gov/current/title-21/section-862.1205
- US National Library of Medicine. Cortisol blood test. MedlinePlus Medical Encyclopedia. Reviewed April 24, 2025. https://medlineplus.gov/ency/article/003693.htm
- Bornstein SR, Allolio B, Arlt W, et al. Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline. The Journal of Clinical Endocrinology and Metabolism. 2016. https://doi.org/10.1210/jc.2015-1710
- Beuschlein F, Else T, Bancos I, et al. European Society of Endocrinology and Endocrine Society Joint Clinical Guideline: Diagnosis and Therapy of Glucocorticoid-induced Adrenal Insufficiency. The Journal of Clinical Endocrinology and Metabolism. 2024. https://doi.org/10.1210/clinem/dgae250
- Crawford AA, Soderberg S, Kirschbaum C, et al. Morning plasma cortisol as a cardiovascular risk factor: findings from prospective cohort and Mendelian randomization studies. European Journal of Endocrinology. 2019. https://doi.org/10.1530/eje-19-0161
- Kwok MK, Kawachi I, Rehkopf D, Schooling CM. The role of cortisol in ischemic heart disease, ischemic stroke, type 2 diabetes, and cardiovascular disease risk factors: a bi-directional Mendelian randomization study. BMC Medicine. 2020. https://doi.org/10.1186/s12916-020-01831-3
- Larsson SC, Lee WH, Burgess S, Allara E. Plasma Cortisol and Risk of Atrial Fibrillation: A Mendelian Randomization Study. The Journal of Clinical Endocrinology and Metabolism. 2021. https://doi.org/10.1210/clinem/dgab219
- Hawley JM, Owen LJ, Lockhart SJ, et al. Serum Cortisol: An Up-To-Date Assessment of Routine Assay Performance. Clinical Chemistry. 2016. https://doi.org/10.1373/clinchem.2016.255034
- Qureshi AC, Bahri A, Breen LA, et al. The influence of the route of oestrogen administration on serum levels of cortisol-binding globulin and total cortisol. Clinical Endocrinology. 2007. https://doi.org/10.1111/j.1365-2265.2007.02784.x
- Nieman LK, Biller BMK, Findling JW, et al. The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline. The Journal of Clinical Endocrinology and Metabolism. 2008. https://doi.org/10.1210/jc.2008-0125
- Debono M, Ghobadi C, Rostami-Hodjegan A, et al. Modified-Release Hydrocortisone to Provide Circadian Cortisol Profiles. The Journal of Clinical Endocrinology and Metabolism. 2009. https://doi.org/10.1210/jc.2008-2380