Irregular periods, stubborn acne or excess hair growth, and then that one word that lingers after a search online: PCOS. Before you draw a conclusion, it helps to know which blood values belong to this picture and what they can and cannot say.
Important to state up front: a blood test does not establish PCOS on its own. PCOS is a clinical diagnosis a doctor makes based on several criteria. Blood values are an important puzzle piece, not a final verdict.
PCOS (polycystic ovary syndrome) is a common hormonal condition in women of reproductive age. Internationally the diagnosis often rests on the Rotterdam criteria, which look at an irregular or absent ovulation, signs of too much male hormone, and the appearance of the ovaries on ultrasound.
Which hormones and blood values belong to PCOS testing?
A doctor usually requests a combination, not a single test. Below are the values that most often play a part and what they show.
| Blood value | What it shows | Pattern that can fit PCOS |
|---|---|---|
| Total testosterone | Male hormone | Sometimes raised |
| Free testosterone | The active part | More sensitive than total; sometimes raised |
| SHBG | Binds sex hormones | Often lowered, raising free testosterone |
| LH and FSH | Cycle hormones | LH sometimes relatively high versus FSH |
| Progesterone (luteal) | Confirms ovulation | Low when ovulation is missed |
| Prolactin and TSH | Rule out other causes | Helps exclude thyroid or prolactin issues |
| Fasting glucose and insulin | Sugar metabolism | Can point to insulin resistance |
When is the best time to test?
Most hormones are best measured early in your cycle (day 2 to 5), if you have one. If you do not have a regular cycle, a doctor may ask you to test at any moment and judge the result in context. Progesterone, by contrast, is measured in the second half, about a week before an expected period, to see whether you ovulated. For glucose and insulin, fasting (8 to 12 hours without food) is important.
How do you read your PCOS result?
No single value is proof on its own. A raised testosterone or a lowered SHBG can fit PCOS, but can also have other causes. A doctor looks at the whole picture: your complaints, your cycle, your blood values and if needed an ultrasound. That is why ruling out other causes, such as a thyroid problem via TSH or a raised prolactin, is a fixed part of the work-up.
The Hormones Women panel brings the sex hormones together, and every result is assessed by a BIG-registered doctor. If you also wish to conceive, the Fertility assessment can give additional insight.
According to NHG and the international ESHRE guideline for PCOS, the diagnosis is emphatically a combination of criteria, not a sum of individual blood values. Want the broader picture? Then read our pillar on PCOS diagnosis and modern management.
What a blood test does not tell you
It is good to be honest about the limits. A blood test does not show the appearance of your ovaries on ultrasound, and in the Rotterdam criteria that is one of the three pillars. Your hormone values can also fall neatly within the reference while you do have PCOS, or deviate slightly without there being PCOS. That sounds confusing, but it fits the idea that PCOS is a pattern, not a single switch that is on or off.
What a blood test does do is give direction and rule out other causes. If an abnormal pattern comes out, that is a good reason to talk further with a doctor or gynaecologist about an ultrasound and about what the values mean in your situation. If a reassuring picture comes out while you still have complaints, that helps you search together in another direction. In both cases the result is a starting point for a conversation, not the end point.
Frequently asked questions
Can one blood test prove PCOS?
No. PCOS is a clinical diagnosis a doctor makes based on several criteria. Blood values are an important part, but do not prove it on their own.
On which cycle day do I test my hormones?
Most hormones are measured early in your cycle (day 2 to 5). If you do not have a regular cycle, a doctor judges the result in context. Progesterone, by contrast, is measured in the second half.
What if my values are normal but I have complaints?
Normal values do not fully rule out PCOS, and complaints can also have another cause. Discuss your complaints and results together with a doctor who looks at the whole.
References
- NHG. NHG-Standaard Amenorroe. Dutch College of General Practitioners. Available via richtlijnen.nhg.org.
- Thuisarts.nl. I have PCOS (polycystic ovary syndrome). Dutch College of General Practitioners. Available via thuisarts.nl.
- ESHRE. International evidence-based guideline for the assessment and management of polycystic ovary syndrome. European Society of Human Reproduction and Embryology. Available via eshre.eu.
Every blood test result through Lunara includes a professional assessment by a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
Autor
Lunarahealth
Dr. Naimi, lekarz wpisany do holenderskiego rejestru BIG, nadzoruje standardy medyczne naszych treści i ocen. Przeczytaj naszą politykę medyczną
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