Cortisol and PCOS: what the research shows and which tests matter

Polycystic ovary syndrome (PCOS) is diagnosed by a clinician from symptoms and tests, and cortisol is not part of the definition. One small study found higher cortisol in the hair of women with PCOS, but it can’t show that cortisol causes it, and the National Institute of Child Health and Human Development (NICHD) says the exact cause of PCOS is unknown. Where cortisol testing does matter is in ruling out Cushing’s syndrome, which can look like PCOS.

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How PCOS is diagnosed

NICHD says women with PCOS usually have at least two of three features. The first is no ovulation, which leads to irregular periods or none. The second is high levels of androgens, or signs of them such as extra body or facial hair. The third is growths in one or both ovaries, often clumps of follicles that stopped developing. NICHD also uses the name Polyendocrine Metabolic Ovary Syndrome (PMOS). The Office on Women’s Health (OWH) says between 5% and 10% of women aged 15 to 44 have PCOS.

OWH is plain that there is no single test. Your doctor may take a history, examine you, and order an ultrasound of the ovaries. Blood tests check androgen levels and other hormones tied to conditions that can be mistaken for PCOS, such as thyroid disease. Cholesterol and diabetes tests may be added. A diagnosis comes once other conditions are ruled out and at least two of the features above are present.

Is cortisol linked to PCOS?

NICHD says genetic and environmental factors contribute to PCOS and its exact cause remains unknown. It describes many symptoms as the result of hormone imbalance: higher androgens, and often a problem with insulin, since high insulin levels may push the body to make more androgens. The NICHD pages we read don’t mention cortisol, and neither does the OWH page. So we don’t say cortisol causes PCOS.

There is research on the question. A 2022 study in Scientific Reports measured cortisol in hair, which reflects cortisol over a longer stretch than one blood draw. In 44 women with PCOS aged 18 to 34 and 49 women without it, hair cortisol was higher in the PCOS group (median 130 versus 63 picograms per milligram of hair). The authors read this as overactivity of the body’s stress hormone system.

Several things limit that reading:

• Morning blood cortisol did not differ between the two groups.
• The PCOS group had a much higher body mass index on average, about 30 compared with about 20.
• Everyone was measured once, so the study can’t say whether higher cortisol came first, came later, or travels with weight, insulin and other differences.
• The authors note that the number of patients was small.

Hair cortisol is also not a routine clinical test. See saliva, urine and hair cortisol tests. The honest summary is that one small study found an association, and nothing we can cite shows a cause.

Why the adrenal glands come up

Androgens aren’t made only in the ovaries. NICHD says the ovaries, testes and adrenal glands all produce reproductive hormones, androgens included. A 2022 review in Diagnostics says DHEA-S, an androgen precursor, is made almost entirely by the adrenals, and that testosterone production in women is shared nearly equally between the ovaries and the adrenals.

That is why a clinician may check an adrenal androgen when someone has extra hair growth or irregular periods. MedlinePlus says the DHEA-S test is used to look for the cause of masculine features in women, such as excess body and facial hair. It says a high result can be a sign of PCOS, congenital adrenal hyperplasia, an adrenal tumor and, rarely, an ovarian tumor. So a high DHEA-S doesn’t point to PCOS on its own. MedlinePlus says no special preparation is needed for the test, and that a provider reads the result alongside your symptoms, age, history and other tests. See the DHEA-S test.

When Cushing’s syndrome looks like PCOS

NIDDK says Cushing’s syndrome can be hard to diagnose, because symptoms like fatigue and weight gain have many causes, and that it may be mistaken for PCOS or metabolic syndrome. In women it can cause excess hair on the face, neck, chest, abdomen and thighs, and periods may become irregular or stop. The Diagnostics review says Cushing’s syndrome has to be ruled out before PCOS can be diagnosed, and that a dexamethasone suppression test is used routinely to tell the two apart.

Cushing’s syndrome from the body’s own overproduction of cortisol is rare, with estimates of about 40 to 70 people per million. NIDDK also says the most common cause overall is long-term, high-dose use of glucocorticoid medicines. Other signs NIDDK lists for Cushing’s, which are not on OWH’s list of PCOS symptoms, include easy bruising, wide purple stretch marks, weak muscles, thin arms and legs, a round face, and a fatty hump between the shoulders. Having PCOS-like symptoms does not mean you have Cushing’s syndrome.

NIDDK says no single test is perfect, so doctors usually do two of these: a 24-hour urine free cortisol collection, a late-night saliva cortisol test, and a low-dose dexamethasone suppression test. A single morning blood cortisol can’t diagnose or rule out Cushing’s syndrome. See high cortisol.

The same review names another condition that has to be ruled out, non-classic congenital adrenal hyperplasia. It says the main test is 17-hydroxyprogesterone, measured at baseline and after an ACTH injection. That is a clinic test. See the 17-OHP test. The review also says that quickly progressing hirsutism may be due to an androgen-secreting adrenal tumor. If body hair, voice or other changes develop fast, see a clinician soon.

Which test answers which question

Your question	What is usually used	Who usually arranges it
Do I have PCOS?	History, exam, androgen and other hormone blood tests, sometimes an ultrasound. No single test.	A clinician
Could it be Cushing’s syndrome?	Two of: 24-hour urine, late-night saliva, low-dose dexamethasone suppression.	A clinician
Is an adrenal hormone adding to my androgens?	DHEA-S is one blood test used in the work-up.	A clinician, or you with a clinician to review it
Could it be non-classic congenital adrenal hyperplasia?	17-hydroxyprogesterone, sometimes after an ACTH injection.	A clinician
Is my thyroid involved?	TSH is the usual first check. See cortisol and the thyroid.	A clinician, or you

If you take birth control pills

Hormonal birth control is one of the medicines OWH lists for PCOS. Estrogen taken by mouth raises the protein that carries cortisol in the blood, so a blood test for total cortisol can read high. A 2024 review in the Journal of the Endocrine Society puts the rise at about 67 percent in women who take birth control pills, a figure it takes from one earlier study. It says tests that measure free cortisol, in urine or saliva, are not affected. Don’t change your pill on your own. Your prescriber decides, and should know about the pill before any cortisol test. See cortisol and birth control.

Questions people ask

Should I have a cortisol test if I have PCOS?

Not as a PCOS test. A cortisol test fits when a clinician suspects Cushing’s syndrome or another adrenal condition, for instance because of easy bruising, wide purple stretch marks or fast-changing symptoms. A morning blood cortisol can be a starting point, never the answer. Tell the clinician about any hormone medicine you take.

Does stress cause PCOS?

NICHD names genetic and environmental factors and says the exact cause is unknown. It does not name stress or cortisol. If you are worried about cortisol, bring it up with the clinician who is managing your PCOS.

What about blood sugar?

NICHD and OWH both describe insulin problems as common in PCOS. OWH says researchers don’t know whether PCOS causes some of its related health problems, whether they cause PCOS, or whether something else causes both. For how cortisol and blood sugar relate, see cortisol and blood sugar.

When to see a clinician

See a clinician if you have irregular or missing periods, extra hair growth, acne or thinning scalp hair. See one sooner if changes develop quickly, or if you also bruise easily, have wide purple stretch marks or have a round face. If you take a steroid medicine, ask your prescriber how it affects any test, and don’t change it yourself.