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Hormone imbalance and PCOS

How it works, which markers are often off, and why you test first.

About 1 in 8 women has PCOS. Since 2026 it is officially called PMOS: polyendocrine metabolic ovarian syndrome. The new name shows better what it is: a hormonal and metabolic condition. A doctor makes the diagnosis. This page helps you understand what is going on and which markers you can have tested.

When is it PCOS?

According to the international guideline, you have 2 of these 3 features, after other causes are ruled out:

Irregular or missing periods.
Too much male hormone: visible (hair growth, acne) or in your blood.
Many small follicles on ultrasound, or a high AMH (adults only).

Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome.

Teede HJ, Tay CT, Laven JJE, Dokras A, Moran LJ et al.

J Clin Endocrinol Metab 2023 · PMID 37580314 · PMCID PMC10505534

Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process.

Teede HJ, Khomami MB, Morman R, Laven JSE, Joham AE et al.

Lancet 2026 · PMID 42119588

How it works

Two things reinforce each other: your brain sends the LH signal too often, and your body responds less well to insulin. Both push your testosterone up. Tap a step in the diagram to see how.

Tap a step to learn more.

Simplified diagram, based on the studies below.

Women with polycystic ovary syndrome have intrinsic insulin resistance on euglycaemic-hyperinsulaemic clamp.

Stepto NK, Cassar S, Joham AE, Hutchison SK, Harrison CL et al.

Hum Reprod 2013 · PMID 23315061

Neuroendocrine dysfunction in polycystic ovary syndrome.

Burt Solorzano CM, Beller JP, Abshire MY, Collins JS, McCartney CR et al.

Steroids 2012 · PMID 22172593 · PMCID PMC3453528

Which markers are often off

The typical picture in PCOS. Not everyone has every change, and one marker means little without the rest.

Total testosterone

Mildly raised. Best measured with LC-MS/MS.

↑ often high

Free testosterone / FAI

Higher, because SHBG is low.

↑ often high

SHBG

Insulin lowers production.

↓ often low

Androstenedione and DHEA-S

Sometimes raised. Mainly useful if testosterone is normal.

↑ often high

Often high, but can be normal. Not a diagnostic criterion.

↑ often high

FSH

Normal or low-normal. Used to rule out early menopause.

usually normal

AMH

High because of many small follicles. Adults only.

↑ often high

Progesterone (day 21)

Low means: no ovulation.

↓ often low

Triglycerides

Higher on average.

↑ often high

HDL

Lower on average.

↓ often low

Glucose

Higher risk. Best tested with a glucose tolerance test (OGTT).

to check

Fasting insulin / HOMA-IR

Often high, but the guideline doesn't recommend it as a routine test.

↑ often high

TSH, prolactin and 17-OH-progesterone

To rule out the thyroid, prolactin and the adrenal glands as the cause.

to rule out

Careful. The pill makes hormone results unreliable. Talk to your doctor if you want to test while you're on it.

Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome.

Teede HJ, Tay CT, Laven JJE, Dokras A, Moran LJ et al.

J Clin Endocrinol Metab 2023 · PMID 37580314 · PMCID PMC10505534

Lipid levels in polycystic ovary syndrome: systematic review and meta-analysis.

Wild RA, Rizzo M, Clifton S, Carmina E

Fertil Steril 2011 · PMID 21247558

Supplements: test first

Many women with PCOS try supplements such as myo-inositol, berberine or chasteberry (vitex). The international guideline sees little evidence: inositol 'could be considered', with limited benefit, and for women trying to conceive the guideline calls it experimental. Supplements aren't harmless either:

Berberine

Blocks liver enzymes that clear medicines, so medicines can act more strongly. Not in pregnancy or breastfeeding.

Chasteberry (vitex)

Can affect prolactin and so hide a high level, which is exactly what you want to rule out. Disrupted an IVF cycle in one case report.

Myo-inositol

Few side effects, but the evidence is limited and uncertain.

Never start without data. The wrong supplement can make your symptoms worse: through side effects, an interaction with your medicines, or because it doesn't fit what's going on for you. So test your markers first, then choose with a doctor.

Inositol for Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis to Inform the 2023 Update of the International Evidence-based PCOS Guidelines.

Fitz V, Graca S, Mahalingaiah S, Liu J, Lai L et al.

J Clin Endocrinol Metab 2024 · PMID 38163998 · PMCID PMC11099481

Repeated administration of berberine inhibits cytochromes P450 in humans.

Guo Y, Chen Y, Tan ZR, Klaassen CD, Zhou HH

Eur J Clin Pharmacol 2012 · PMID 21870106 · PMCID PMC4898966

Vitex agnus castus effects on hyperprolactinaemia.

Puglia LT, Lowry J, Tamagno G

Front Endocrinol (Lausanne) 2023 · PMID 38075075 · PMCID PMC10702745

Multiple follicular development associated with herbal medicine.

Cahill DJ, Fox R, Wardle PG, Harlow CR

Hum Reprod 1994 · PMID 7989506

That's why it starts with testing. Only when you know which markers are off can you and your doctor choose what makes sense, and see at the next test whether it works.

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