Periods that come every six weeks, then every three months. Acne that did not go away after the teenage years. Hair on the chin or chest that seems to grow faster than it should. Each of these on its own is common, and each can have more than one explanation. When they appear together, many women start reading about polycystic ovary syndrome (PCOS). This guide explains what a PCOS blood test measures, what it cannot show on its own, and how it fits with current guidance.
A quick word on the name
The NHS now uses the name polyendocrine metabolic ovarian syndrome (PMOS) for the condition long known as PCOS (NHS, PMOS). The new name reflects that it is a hormonal and metabolic condition, not only an ovarian one. Most research and laboratory tests still use "PCOS", so we use both terms here.
How PCOS is identified
The 2023 International Evidence-based Guideline for PCOS, developed with professional societies and women with PCOS across many countries, sets out how the condition is assessed (Teede et al., 2023). In adults it rests on a combination of features, after other conditions that look similar have been ruled out:
- irregular cycles or signs that ovulation is not happening regularly;
- signs of higher androgens, seen either clinically (acne, excess hair) or in blood tests;
- polycystic ovarian appearance on ultrasound, or, as an alternative in adults only, a raised anti-Müllerian hormone (AMH).
The guideline also stresses that PCOS goes beyond the ovaries, with links to metabolic risk factors, cardiovascular health, sleep and emotional wellbeing (Teede et al., 2023).
Adolescents are different
For teenagers, the guideline recommends looking for both irregular cycles and androgen excess, and advises that ultrasound and AMH should not be used during adolescence (Peña et al., 2025). Young people with only one of these features may be considered "at risk" and followed up over time. Under-18s who have blood taken at an LML collection point must attend with an adult.
What the Polycystic Ovary Syndrome Screen measures
The Polycystic Ovary Syndrome Screen SHORT in the BPR catalogue groups the markers most often requested when PCOS is being considered:
- Testosterone and SHBG (sex hormone binding globulin). SHBG carries testosterone in the blood; LML notes that SHBG is often lower in PCOS, leaving more testosterone free to act.
- FSH and LH, the pituitary hormones that control the ovaries.
- Insulin and glucose, which give a view of how the body handles sugar. The NHS lists insulin resistance among the things checked by blood tests for PMOS (NHS, PMOS).
- TSH, because thyroid problems can also disturb periods.
- Cholesterol profile (total, LDL, HDL and triglycerides), reflecting the metabolic side of the condition.
Because insulin and glucose are included, LML collects this panel in two tubes, including one specifically for glucose. LML can also send a doctor's report the day after results are available, if required.
Related tests in the catalogue
If testosterone needs a closer look, the Testosterone Plus Profile adds albumin to calculate free testosterone. Antimullerian Hormone (AMH Plus) is available separately for adults whose doctor wants AMH as part of the assessment.
What a blood test cannot do alone
No single result confirms PCOS. Hormone values depend on the timing of the sample, recent contraception and other medicines, and must be read alongside symptoms, history and sometimes an ultrasound. Other conditions can raise androgens or disturb cycles, which is why guidelines ask doctors to rule them out first (Teede et al., 2023). A normal panel does not exclude PCOS, and an abnormal value does not mean you have it.
What the panel offers is a structured starting point for a conversation with your GP or a gynaecologist, especially if you already have symptoms that bother you.
