A PCOS blood panel comes back as eight or nine abbreviations with a number, a unit, and a reference range beside each. Nothing on the page says what any of them is for, which of them matter together, or why three of them appear to have nothing to do with ovaries.
This is what each one is doing there. It is not an interpretation of your results — a number only means something next to its own laboratory’s range, your cycle day, and everything else on the sheet, and that combination is a clinician’s job. But knowing what was asked and why turns the results conversation into something you can follow.
First: there is no blood test for PCOS
This is the thing that surprises people most, and it explains the shape of the whole panel.
PCOS is diagnosed against the Rotterdam criteria, which require two of three findings: irregular or absent ovulation, raised androgens (either measured in blood or visible as symptoms), and polycystic ovarian morphology. Under the 2023 international guideline, that third one can now be assessed in adults by an AMH blood test rather than an ultrasound — one of the more consequential changes in the update, because it makes the workup possible in primary care.
Two further points from the same guideline are worth knowing before you read your own results:
- If irregular cycles and raised androgens are both present, neither an ultrasound nor AMH is needed. The diagnosis is already made on two criteria, and the third test adds nothing.
- In adolescents, AMH and ultrasound are not recommended for this at all — polycystic-looking ovaries are common enough in the years after menarche that the finding does not distinguish much.
So half the panel is there to establish criteria, and the other half is there to rule out conditions that produce the same picture.
The androgen tests
Total testosterone
The headline androgen measurement. In PCOS it may be raised, but plenty of people with PCOS have a total testosterone inside the reference range and are diagnosed on the clinical signs instead — the criterion is hyperandrogenism, and that can be biochemical or clinical.
A normal total testosterone therefore does not rule anything out, which is the single most common misreading of this panel.
SHBG, and the free androgen index
Sex hormone binding globulin is a protein that binds testosterone and takes it out of circulation. Because of that, the total figure alone can be misleading: the same total with a low SHBG means more unbound, active hormone.
The free androgen index is calculated from the two — it is not measured directly — and is often the more informative number of the three. If your results show a normal testosterone and you are wondering why the conversation continued anyway, this is usually why.
DHEAS and androstenedione
Other androgens, sometimes added. Their main use is one of location: DHEAS comes largely from the adrenal glands rather than the ovaries, so a markedly raised DHEAS points the investigation somewhere other than PCOS.
AMH
Anti-Müllerian hormone is produced by small follicles in the ovaries, so it rises roughly with how many of them there are. That is what makes it a stand-in for the ultrasound finding of polycystic ovarian morphology in adults, under the 2023 guideline.
Two things it is not:
- It is not a PCOS test on its own. It stands in for one of three criteria, and two are needed.
- It is not a fertility score, although it is widely read as one. It says something about the number of follicles, not about egg quality and not about whether you will conceive. AMH tends to be higher in PCOS, and a high result is not a prediction in either direction.
The tests that are there to rule things out
These three usually confuse people most, because none of them is about ovaries.
TSH — thyroid function. An underactive or overactive thyroid can cause irregular cycles, fatigue and weight change on its own. It has to be excluded before those symptoms are attributed to anything else.
Prolactin — a raised prolactin can stop ovulation entirely, and has causes of its own that need finding.
17-hydroxyprogesterone — screens for non-classic congenital adrenal hyperplasia, which is uncommon, produces a very similar picture of irregular cycles and raised androgens, and is managed differently. It is usually measured in the morning, and early in the cycle where there is a cycle to be early in.
If your panel came back “all normal” apart from one of the androgen measures, these three being normal is part of why the conversation moved to PCOS.
LH and FSH
Often measured, frequently over-interpreted. The ratio between them tends to run higher in PCOS, but it is not a diagnostic criterion under the current guideline and a normal ratio excludes nothing. If you have read that a 3:1 LH to FSH ratio means PCOS, that is a piece of older thinking that has outlived its evidence.
Their timing matters more than most: both swing considerably across a cycle, so a result without a cycle day beside it is hard to read at all.
The metabolic half of the panel
PCOS is associated with insulin resistance independently of weight, and the guideline treats metabolic assessment as part of ongoing care rather than a one-off at diagnosis.
HbA1c reflects average blood glucose over roughly the previous two to three months. Unlike most of this panel it does not need fasting and does not care what day of your cycle it is, which is why it turns up so often.
Fasting glucose, or an oral glucose tolerance test, may be used instead or in addition. The OGTT is the more sensitive of the two and the more unpleasant — it is the one where you drink a glucose solution and get bled twice.
A lipid panel — total cholesterol, LDL, HDL, triglycerides — is commonly included for the same reason.
The useful thing about this half is that it is the half that repeats. These are the numbers you will see again in a year, and a trend across three results says something a single result cannot.
Vitamin D, ferritin, B12
Not diagnostic, frequently added, and worth having in the record because they have their own explanations for fatigue. A tired person with a low ferritin has a finding, not a mystery.
Why one number rarely means what a search result says
Three things make a single value less informative than it looks:
- Reference ranges are laboratory-specific. Two labs can report the same sample as 1.9 and 2.1 with different ranges around each. Comparing your number to one from a forum post compares two different measurements.
- Cycle day changes several of these considerably. LH, FSH and progesterone in particular. A result without a date is missing half its meaning.
- The criteria are combinations. Almost nothing here is diagnostic alone, which is precisely why the panel is long.
Which is the argument for keeping your own results over time rather than reading each one on arrival. A testosterone of 2.1 tells you very little. A testosterone that has been 1.4, 1.8 and 2.1 over eighteen months tells you a direction, and a direction is something to raise.
What to do with the results
Ask for a copy — you are entitled to one, and photographing the whole sheet takes ten seconds. Keep the reference ranges with the numbers, because the numbers are meaningless without them, and keep the date.
Then ask the two questions that decide what happens next: what would change your mind about this? and when should this be repeated? The second one is the one people leave without.