What is PCOS?
In a normal cycle one follicle matures under the influence of FSH, releases ever more oestradiol, and a peak of LH sets ovulation going. In PCOS that maturation stalls: the ovaries contain many small follicles in development, but none becomes dominant, probably under the influence of androgens, LH and insulin. Women with PCOS therefore have a raised LH with a normal FSH, and most a raised testosterone and other androgens such as DHEA. Insulin plays a role of its own in that. PCOS is linked to insulin resistance, as in type 2 diabetes, and a high insulin lowers SHBG, the protein that binds testosterone. More free testosterone then circulates, and insulin also stimulates the production of androgens in ovaries and adrenal glands. That is why a PCOS picture is read from two sides, the hormones and the sugar and fat balance beside them, and why losing weight and exercise with excess weight calm the whole chain: less insulin, more SHBG, less free testosterone, and ovulation more often. The exact cause is unknown, disposition plays a part, and PCOS also occurs with a normal build. The diagnosis asks for at least 2 of 3 features: an absent or infrequent period, signs of too many androgens in skin or blood, and polycystic ovaries on ultrasound. In the long term PCOS carries a higher chance of type 2 diabetes and cardiovascular disease, and that is what the sugar and fat side is measured for every few years.
Which blood values show PCOS?
Every value below has its own page with the reference ranges of four Dutch labs.
| Value | What it shows | Points here when |
|---|---|---|
| Total testosterone | Raised in most women with PCOS. Only readable beside SHBG, and the upper limit differs from 1.7 to 2.6 nmol/L per lab. | high |
| SHBG | Falls with a high insulin, so more testosterone circulates free. Rises on the pill, which distorts the total. | low |
| FAI (free androgen index) | Total testosterone divided by SHBG: the working share in one number. | high |
| Free testosterone | The same question, calculated from total, SHBG and albumin. | high |
| LHdefining | Raised in PCOS, while FSH stays normal. Only assessable in the first days of the cycle. | high |
| FSH | Normal in PCOS. Strongly raised points instead to a premature menopause, the picture next door. | abnormal |
| Prolactin | A high prolactin also disturbs the cycle. Belongs in the panel to exclude that other cause. | abnormal |
| Oestradiol | Stays continuously present in anovulation without progesterone; low in a premature menopause. | abnormal |
| Fasting glucose | The sugar side: PCOS goes with insulin resistance as in type 2 diabetes. | high |
| HbA1c | The three-month average, for the same question. | high |
| Triglycerides | Rises when the liver sees too much insulin; often the earliest trace. | high |
| HDL Cholesterol | Falls in the same pattern. | low |
What are the symptoms of PCOS?
These complaints are described for PCOS in guidelines and research. None of them is exclusive to it: the same complaints fit many other explanations, and an abnormal value can exist without any of them.
PCOS can go unnoticed for a long time. Excess weight adds to the suspicion, but PCOS also occurs with a normal build, and the period is usually infrequent rather than gone altogether. Without skin complaints and without attention to the cycle it then often only stands out when wanting a child. The sugar and fat side is silent for years too.
- Irregular, infrequent or absent periods (oligomenorrhoea or amenorrhoea)in the guideline
In most women with PCOS the periods are too infrequent; prolonged absence is rare according to the NHG.
- Excess hair growth in a male pattern (hirsutism)in the guideline
The hair pattern runs in families and differs by ethnicity. In secondary care a Ferriman-Gallwey score below 8 counts as normal.
- Acnein the guideline
- Hair loss in a male pattern (androgenic alopecia)in the guideline
Also described at iron deficiency.
A complaint points in more than one direction, and a measurement explains no complaint: blood testing shows where your values stand, the reading and the diagnosis belong with your GP. The complaint list follows the Dutch GP guideline on amenorrhoea (NHG).
What causes PCOS?
Hormonal
The ovaries make too many androgens, and that brings the cycle to a halt.
Insulin
Insulin resistance feeds the hormonal picture from two sides.
Weight and predisposition
The precise cause is unknown and probably multifactorial.
- Excess weight, which adds to the suspicion and strengthens the insulin side
- PCOS also occurs at a normal build
What is PCOS confused with?
Each with the one value that tells the two apart.
Premature menopause
Also absent periods, but with a strongly raised FSH and a low oestradiol: the NHG speaks of a premature menopause at FSH above 40 IU/L with oestradiol below 100 pmol/L. In PCOS, FSH is normal.
Distinguishing value: FSH
Hyperprolactinaemia
A high prolactin, from medication or a prolactinoma, also suppresses the cycle. Prolactin itself decides.
Distinguishing value: Prolactin
Androgen-producing tumour
Hirsutism that arises in a short time, with other signs of virilisation and a strongly raised testosterone. Rare, but the reason the NHG watches the pace of the complaints.
Distinguishing value: Total testosterone
Underactive thyroid
Also cycle disturbances and weight gain, through a different hormone. TSH keeps the two apart.
Distinguishing value: TSH
What you do about PCOS
Focus on insulin, because that is the link you hold in your own hands. With excess weight losing 5 to 10% of your weight is the treatment that improves the whole picture: less insulin lifts SHBG, lowers free testosterone, brings ovulation back in many women and calms the skin. Eat with few fast sugars, cut soft drinks and fruit juice, and eat protein, fibre and vegetables with every meal; exercise daily and do strength training, because muscles take up glucose without insulin. Sleep enough and keep your weight stable even with a normal build, because belly fat lowers SHBG then too. The pill regulates the cycle, protects the womb lining with an absent period and lowers the androgens, and is the first choice when there is no wish for a child; with excess hair, hair removal helps beside the pill, and when wanting a child, inducing ovulation is the way once weight is in order. Metformin helps with an impaired glucose and sometimes with the cycle, and at its core does the same as losing weight. Stop smoking, because that strengthens the vascular side of the picture. Have fasting glucose, HbA1c, the fats and blood pressure measured every few years, even without complaints, because the sugar and fat side of PCOS is silent for years and the chance of type 2 diabetes is raised. Measure hormones only when the question calls for it, in the first days of the cycle and without the pill, otherwise the total says little.
From which LH does a lab call it high?
This is what the four largest Dutch labs publish themselves, side by side.
2.4 – 10.9U/l
Between 1.8 and 2.4 and between 10.9 and 12.6 it differs per lab, because each lab sets its limits on its own method and population. Above 12.6 every lab calls it abnormal.
Every age group per lab
| Lab | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | Follicular phase (from 14 yrs) | 1.8–11.8 U/l |
| Mid-cycle (from 14 yrs) | 7.6–89.1 U/l | |
| Luteal phase (from 14 yrs) | 0.6–14.0 U/l | |
| Post-menopausal (from 14 yrs) | 5.2–62.0 U/l | |
| Men from 20 yrs | 0.6–12.1 U/l | |
| Certe2026 | Men (pubertal and post-pubertal) | 1.7–8.6 U/l |
| Women follicular phase (day 1–12) | 2.4–12.6 U/l | |
| Women ovulation peak (day 13–15) | 14–95.6 U/l | |
| Women luteal phase (day 16–28) | 1–11.4 U/l | |
| Women post-menopausal | 7.7–58.5 U/l | |
| Clinical Diagnostics2026 | Men | 1.2–8.6 U/l |
| Women follicular phase | 2.1–10.9 U/l | |
| Women ovulation peak | 19.2–103.0 U/l | |
| Women luteal phase | 1.2–12.9 U/l | |
| Women post-menopausal | 10.9–58.6 U/l |
How to get PCOS measured
- Fasting
- Fasting for the sugar and fat side; not for the hormones themselves. The day of the cycle does count: LH, FSH and oestradiol belong in the first days of the cycle, progesterone in the second half, and that takes two draws.
- Material
- Venous blood, drawn at one of our collection points.
- Results
- Results within 24 hours of analysis, in the app.
- Referral
- No referral from a GP required.
- Which test
- The comprehensive test (€229, single test) measures the values on this page.
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What are the symptoms of PCOS?
An irregular, infrequent or absent period, and signs of too many androgens: excess hair in a male pattern, acne and hair loss on the head. Excess weight adds to the suspicion, but PCOS also occurs with a normal build, and the sugar and fat side you do not feel. The diagnosis asks for at least 2 of 3 features, with polycystic ovaries on ultrasound as the third.
Which blood values belong with PCOS?
A raised LH with a normal FSH, and in most women a raised testosterone or other androgens. SHBG is often low through insulin, so more testosterone circulates free; the free androgen index puts that together. Beside that the sugar and fat side: fasting glucose, HbA1c, triglycerides and HDL, because PCOS is linked to insulin resistance and that side is silent for years. Measure the hormones in the first days of the cycle and without the pill.
Why does the GP not measure testosterone in PCOS?
Because the total says little without SHBG beside it: the pill raises SHBG and with it the total, while a low SHBG can hide a normal total. Moreover the upper limit differs sharply per report, for a woman of 30 from 1.7 to 2.6 nmol/L. The diagnosis therefore hangs on the cycle, the skin and if needed the ultrasound, and the hormones are measured where the question calls for it, such as when wanting a child.
Is PCOS linked to insulin resistance?
Yes, and that is the link you hold in your own hands. A high insulin lowers SHBG, so more testosterone circulates free, and stimulates the production of androgens in ovaries and adrenal glands. That is why you also read the sugar and fat values with PCOS, and why losing weight with excess weight improves the whole picture: less insulin, more SHBG, less free testosterone and ovulation more often. The chance of type 2 diabetes is raised in the long term.
Can you have PCOS without excess weight?
Yes. Excess weight adds to the suspicion, but PCOS also occurs in women with a normal build, and the diagnosis hangs on the cycle, the androgens and the ultrasound, not on weight. With a normal build too insulin often plays a part, and then the same things help: few fast sugars, strength training and enough sleep. Excess weight does strengthen the insulin side, and that is why it counts in the approach.
Sources
- 1.NHG-Standaard Amenorroe. 2018. richtlijnen.nhg.org
- 2.Teede HJ et al., Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome, Journal of Clinical Endocrinology & Metabolism. 2023. doi.org
- 3.Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group, Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome, Human Reproduction. 2004. doi.org
This page explains what a result means. It is not a diagnosis and not treatment advice. Discuss complaints or an abnormal value with your doctor.
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