PCOS or PMOS — what's in the name?
The long-used name "polycystic ovary syndrome" is widely seen as misleading: many people with the condition do not have true cysts, and the effects reach well beyond the ovaries — insulin resistance, lipid changes, fatty liver, mood and sleep. The newer term PMOS (polyendocrine metabolic ovarian syndrome) is being phased in. You will see both names on lab requests and in articles for some time; they refer to the same condition.
How it is usually diagnosed
Most guidelines look for a combination of features rather than one result:
- Irregular or absent ovulation — long cycles, few periods, or none
- Signs of excess androgens — acne, excess facial/body hair, scalp hair thinning, or raised androgens on a blood test
- Polycystic-appearing ovaries or a high AMH — in adults, depending on the guideline used
Other conditions with similar features must be excluded first, which is where much of the blood work comes in.
The blood markers doctors commonly review
| Marker | Why it is checked | What to know |
|---|---|---|
| Total & free testosterone | Looks for biochemical hyperandrogenism (excess androgens). | Often mildly raised in PCOS/PMOS. Markedly high values prompt a search for other causes. |
| SHBG | Carrier protein that binds testosterone; low SHBG raises 'free' androgen. | Tends to run low with insulin resistance. Used to calculate the Free Androgen Index (FAI). |
| LH and FSH | Pituitary hormones that drive ovulation. | LH can be relatively high versus FSH, but the ratio is not diagnostic and is not required. |
| AMH | Reflects the number of small follicles in the ovaries. | Often higher in PCOS/PMOS; guidelines allow it as an alternative to ultrasound in adults, but it varies by assay. |
| 17-OH progesterone | Screens for non-classic congenital adrenal hyperplasia. | A look-alike condition that must be excluded. |
| Prolactin | High prolactin can stop periods. | Checked to rule out other causes of irregular cycles. |
| TSH | Thyroid disease can mimic cycle irregularity. | Part of the standard exclusion work-up. See our thyroid guide. |
| Fasting glucose, HbA1c, fasting insulin / OGTT | Assess insulin resistance and diabetes risk. | Many with PCOS/PMOS have normal glucose but raised insulin, so glucose alone can miss it. |
| Lipid panel | Cardiometabolic risk screening. | Higher triglycerides, lower HDL and higher non-HDL cholesterol are common patterns. |
| ALT / liver enzymes | Fatty liver (MASLD) is more common with insulin resistance. | Mild ALT elevation is worth discussing with a clinician. |
Reference ranges differ between laboratories and with age, so always compare against the interval printed on your own report.
Androgens: testosterone, SHBG and the Free Androgen Index
Total testosterone measures everything circulating, most of it bound to SHBG. Only the free fraction is biologically active. When insulin is high, the liver makes less SHBG, so more testosterone is free — which is why a person can have a "normal" total testosterone but a raised Free Androgen Index (total testosterone ÷ SHBG × 100). Where possible, testing is best done in the early morning, in the early follicular phase if you still have periods, and off hormonal contraception.
LH, FSH and the "LH:FSH ratio"
A high LH relative to FSH is a classic textbook finding, but it is inconsistent between people and moves with the cycle. Current guidelines do not require it for diagnosis. FSH is more useful for ruling out primary ovarian insufficiency, where it is raised.
Insulin resistance: why glucose alone can mislead
Insulin resistance is common in PCOS/PMOS, including in lean women. The body compensates by making more insulin, which keeps glucose normal for years. That is why a normal fasting glucose or HbA1c does not exclude it. Clinicians may add:
- Fasting insulin — raised values suggest resistance, though assays and cut-offs are not standardised
- Oral glucose tolerance test (OGTT) — often recommended, as it can reveal impaired glucose handling that fasting tests miss
- HbA1c — a 3-month average; see our HbA1c guide
Cholesterol, triglycerides and long-term risk
PCOS/PMOS is associated with higher triglycerides, lower HDL and higher non-HDL cholesterol, which add to cardiovascular risk over time. A lipid panel is a sensible baseline and a useful way to track the effect of lifestyle changes. Our lipid panel guide explains each marker.
Other results that often come up
- Ferritin and vitamin B12 — heavy periods can deplete iron, and metformin can lower B12 over long-term use. See ferritin and B12.
- Vitamin D — commonly low and often checked, though evidence for supplementing to treat PCOS/PMOS itself is limited.
- TSH — to exclude thyroid disease; see the thyroid test guide.
Tracking your cycle alongside your labs
Lab numbers are a snapshot; cycle length, symptoms, sleep, training and mood tell the story between tests. Apps such as Nitya Health — a women's health app that combines period and cycle tracking, a daily routine planner, workout logging and an AI health coach — can help you keep that record in one place and bring clearer data to your appointment. Nitya Health also lists a PCOS/PMOS symptom checker as a quick way to flag early signs. A symptom checker is not a diagnosis, but it can help you decide whether to book a proper work-up.
Questions to take to your appointment
- Were my hormone tests timed appropriately for my cycle, and was I on contraception?
- Should I have an OGTT or fasting insulin as well as glucose and HbA1c?
- Have other causes — thyroid, prolactin, non-classic CAH — been excluded?
- How often should I repeat lipids, glucose and liver tests?
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