Cortisol and the menopause: sleep, hot flushes, HRT and testing

There is no cortisol test for the menopause, but the menopause does change how cortisol behaves and how a cortisol test should be read. The gap between men's and women's cortisol closes after the menopause, small studies link poor sleep and hot flushes with higher long-term cortisol, and HRT taken as tablets can make a blood cortisol result read falsely high.¹²³⁴ If your question is whether your cortisol has been running high over recent months, through a stretch of broken sleep or a demanding time of life, a hair test answers it most directly. It is the most accurate way to measure long-term cortisol from a single sample, and far more consistent from one test to the next than blood, saliva or urine.⁵ What it cannot do is diagnose the menopause, or tell you whether a particular symptom is caused by cortisol.

How cortisol changes around the menopause

Before the menopause, men tend to produce more cortisol than women, with a higher morning peak, a higher night-time low and a bigger rise in the half-hour after waking. After the menopause that difference is no longer seen.¹ Age changes the daily pattern as well: the gap between the daily high and low narrows, the early-morning rise comes earlier, the hourly pulses of cortisol get smaller and the night-time low rises.¹ Our guide to the daily cortisol rhythm explains how the normal pattern works.

Long-term cortisol measured in hair shifts with age too. In 654 adults with an average age of 65.8, hair cortisol rose with age, and once other factors were allowed for, only age and smoking still predicted it.⁶ Large hair studies of older adults still tend to find somewhat higher levels in men: in the Whitehall II study of people aged 59 to 83, women's hair cortisol was 17 per cent lower.⁷ None of this is a disorder. It means a result is most useful read against people of a similar age and sex, and against your own earlier results. See cortisol and ageing and cortisol in men and women.

Sleep, hot flushes and long-term cortisol

Poor sleep and hot flushes are two of the most common complaints around the menopause, and both have been linked with higher hair cortisol, though only in small studies. In 145 women aged 50 to 64, higher hair cortisol went with worse scores on the Pittsburgh Sleep Quality Index, a standard sleep questionnaire, and women who took a long time to fall asleep had higher hair cortisol than women who did not.² In a pilot study of 45 midlife Latina women, having any hot flushes or night sweats in the previous two weeks was linked with higher hair cortisol. Once perceived stress was taken into account the link was only suggestive, and the authors describe their findings as exploratory.³

Both studies were cross-sectional: they measured each woman once, so they cannot show which came first. Higher cortisol might disturb sleep, broken sleep might raise cortisol, or both might reflect something else, such as stress. There is good evidence for one direction at least. In a laboratory study, partial and total sleep loss raised cortisol the following evening by 37 and 45 per cent.⁸ Hair cortisol does not diagnose the menopause or track its stages. Read more in cortisol and sleep.

HRT and blood cortisol tests: why the route matters

Oestrogen in HRT can be taken as tablets, or through the skin as patches, a gel or a spray.⁹ That choice is usually made for other reasons, but it matters for a blood cortisol test. About 90 per cent of the cortisol in your blood is bound to a carrier protein called corticosteroid-binding globulin (CBG), and a standard blood test measures the total. Oestrogen taken by mouth raises CBG, which pushes total cortisol up even when the active, free cortisol has not changed.¹

The effect is large. In a study of 37 women with an average age of 33, those taking oral oestrogen had 67 per cent higher total blood cortisol than women taking none: 660.9 against 395.4 nmol/L, or about 24.0 against 14.3 µg/dL. Women using oestrogen through the skin had levels no different from the women taking none (334.7 nmol/L), and saliva cortisol, which reflects the free hormone, was similar in all three groups.⁴ Those women were younger than the menopause, but oestrogen tablets work the same way whatever they are taken for.¹

Guidelines take this seriously. NICE advises that people taking oral oestrogen stop it for six weeks before blood cortisol is measured, because otherwise the result reads falsely high.¹⁰ The Endocrine Society notes that the overnight dexamethasone suppression test gives false-positive results in about half of women on the combined pill, and advises withdrawing oestrogen-containing drugs for six weeks before testing wherever possible.¹¹ A 2021 consensus warns that the test may be unreliable in women taking oral oestrogen.¹² The authors of the oestrogen study suggested it is probably unnecessary to stop patch or gel oestrogen routinely before testing.⁴ Do not stop HRT on your own to prepare for a test: ask the doctor who arranged it, and tell them exactly which type you use.

We have not found a study of hair cortisol in women taking HRT. Studies of the combined contraceptive pill, which also delivers oestrogen by mouth, have found at most a small and inconsistent effect on hair cortisol, nothing like the two-thirds rise seen in blood.¹³¹⁴ If you use HRT, tell the laboratory, as you would for any hormone medicine.

When symptoms overlap with cortisol conditions

Some changes around the menopause overlap with the symptoms of Cushing's syndrome, the rare condition caused by too much cortisol. The NHS lists more fat around the tummy, low sex drive, mood changes and irregular or absent periods among its symptoms, alongside more specific signs such as a red, round face, easy bruising, stretch marks and weakness at the top of the arms and legs.¹⁵ Its most common cause is taking high-dose steroid medicine for a long time.¹⁵ Cushing's syndrome from the body's own cortisol is rare: European studies report two to three new cases per million people a year.¹¹

Low cortisol can overlap too. Addison's disease causes extreme tiredness, weight loss, dizziness on standing, darker patches of skin, and anxiety and depression.¹⁶ If you have symptoms like these, especially the more specific ones, see your GP rather than putting them down to the menopause or relying on a home test. Our guides to high cortisol symptoms, low cortisol symptoms and getting a cortisol test from your doctor explain what to expect.

What a cortisol test can and cannot tell you

Each test answers a different question. A blood or saliva test shows your cortisol at the moment of the sample, which moves with the time of day, a bad night and the stress of the test itself. A hair test shows the average over roughly the past three months, because scalp hair grows about 1 cm a month and the 3 cm nearest the scalp are tested.¹⁷ Growth varies from 0.6 to 1.4 cm a month, and new hair takes a few weeks to emerge, so the window is approximate and ends a little before the day the sample is cut.¹⁷¹⁸

For long-term cortisol, hair is the stronger measure. In a study of adults who gave saliva three times a day for 30 days, hair cortisol tracked their 30-day saliva average (r = 0.61). The same people's hair results correlated at r = 0.84 from one month to the next, against 0.38 to 0.61 week to week for saliva and 0.59 to 0.68 for 24-hour urine.⁵ Hair cortisol does not vary with the time of day the sample is cut.¹⁹ That makes it the most accurate way to measure long-term cortisol from a single sample, which suits a question about months of disrupted sleep rather than one bad morning.

The limits are just as clear. A hair test cannot tell you whether you are perimenopausal, which hormone is behind a symptom, or whether cortisol caused it. It does not diagnose or rule out Cushing's syndrome or adrenal insufficiency, which are diagnosed with blood, saliva and urine tests and dynamic tests arranged by a doctor.¹¹¹⁰ And the menopause research is small and cross-sectional, so there are no menopause-specific ranges.²³ For a side-by-side view, see hair vs blood cortisol tests.

Reading a hair cortisol result in midlife

Your result comes in picograms of cortisol per milligram of hair (pg/mg), shown against the laboratory's own range. Ranges differ greatly by method: a recent LC-MS/MS study of healthy adults set a range of 0.84 to 8.07 pg/mg, while an early immunoassay study found 17.7 to 153.2 pg/mg.²⁰²¹ So compare your result only with the range on your own report.

A few things common in midlife can lower a result. In Whitehall II, people who dyed their hair had 12.5 per cent lower hair cortisol, and heat treatments have been linked with lower values too.⁷¹⁴ Tell the laboratory about dye, heat treatments, HRT and any steroid medicines, including creams and inhalers. A result is most useful as a baseline: testing again after three to six months shows whether changes to sleep, HRT or workload have moved it. See hair cortisol results explained and how to lower cortisol.