PCOS Blood Test: Which Labs Doctors Check and Why

Your doctor took blood for suspected PCOS, and the report lists testosterone, LH, FSH, TSH and a string of other abbreviations. This post sorts out which of them the guidelines use for the diagnosis and which are there to rule out something else. You can file the report in a folder or in Sam's Health Vault: with your consent, Sam reads the values. For rows such as testosterone, LH or FSH the name, value and unit stay as printed, plus the first reference range your lab printed.

In May 2026 an international consensus renamed PCOS polyendocrine metabolic ovarian syndrome (PMOS). During the three-year transition your report or letter may say PMOS or PMOS (formerly PCOS). It is the same condition.

What to write down about your cycle, skin and hair before the first appointment is in PCOS: log your cycle and symptoms for the doctor. What else Sam records for this condition is on the PCOS page. Who does what at the first appointments is in Which doctor for PCOS: GP, gynecologist or endocrinologist. Which tests you get is up to your doctor.

Which blood tests do doctors order for suspected PCOS?

The 2023 international evidence-based PCOS guideline and, according to the Deutsches Ärzteblatt, the German S2k guideline (AWMF 089-004) use the same rule. Adults need two of three features, and other causes have to be ruled out first. One feature is signs of raised male hormones. You can see them, as excess hair growth for example, or measure them in the blood. So the blood tests have three jobs: measure male hormones, rule out other causes and check metabolism.

Not everyone gets every test. If irregular cycles and signs of raised male hormones are already present, the guideline says AMH is not needed.

Why testosterone, and why does the lab matter?

For male hormones, also called androgens, the guideline starts with total and free testosterone. Free testosterone can be estimated with the calculated free androgen index, or FAI. If testosterone is not raised, the guideline says your doctor could consider androstenedione and DHEAS. Both are less specific, and DHEAS falls with age.

How the sample is measured makes a difference. The guideline asks labs to use tandem mass spectrometry (LC-MS/MS). Direct immunoassays measure testosterone less accurately, it says. Reference ranges also vary widely between methods and labs. They are often drawn from groups that very likely included women with PCOS.

So read a result against the range printed on the same report. Bring earlier reports in the original rather than copying numbers by hand. And it is fine to ask which method your lab used.

The guideline adds that repeated androgen measurements play a limited role in the ongoing assessment of adults.

Can you have PCOS with normal blood tests?

Yes. Raised male hormones are only one of three features, and they do not have to show up in the blood. In adults, excess hair growth, called hirsutism, on its own counts as a sign of raised male hormones and PCOS, the guideline says. Blood tests add the most when there are few or no visible signs.

In adults, the diagnosis can also rest on no androgen feature at all: irregular cycles plus polycystic-looking ovaries on ultrasound or a raised AMH level. Then there are the limits of measurement, meaning less accurate methods and wide ranges. And on combined oral hormonal medication, male hormones are very hard to assess reliably.

So a result inside the printed range does not rule PCOS out. A result outside it is not a diagnosis on its own. Your doctor weighs it with your cycle, skin and hair. Do not put off an appointment because your numbers look fine.

Which tests rule out other causes?

PCOS only applies once other causes are ruled out. The international guideline names three blood tests for this:

• TSH, for the thyroid. What TSH, free T4 and free T3 mean is explained in TSH results explained.
• Prolactin, to rule out hyperprolactinemia.
• 17-OHP, for non-classic congenital adrenal hyperplasia, an inherited adrenal disorder.

If periods have stopped altogether and the features are more severe, the guideline calls for further checks. These include whether the brain's control of the hormones is disturbed (hypogonadotropic hypogonadism), Cushing's syndrome, or a tumor that makes male hormones. The German guideline also names thyroid disease, tumors and Cushing's syndrome as causes to rule out, according to the Deutsches Ärzteblatt.

When periods stop, the first test is usually a pregnancy test, says the MSD Manual. As further blood tests it lists prolactin, thyroid hormones, FSH and male hormones.

What about LH, FSH and the LH/FSH ratio?

Some reports show LH and FSH, sometimes with an LH/FSH ratio. Neither is one of the three features in the international guideline. A review of the guideline's diagnostic algorithm lists FSH and LH alongside TSH, prolactin and 17-OHP as tests that help rule out other causes.

An NHS hospital lab in Gloucestershire notes that the ratio can be normal in PCOS. For the diagnosis it names the two-of-three rule. So a normal ratio does not rule PCOS out. The same lab says FSH is of no value while you take combined hormonal medication.

Why are glucose and blood lipids part of it?

Women with PCOS have a higher risk of impaired glucose metabolism and type 2 diabetes, regardless of age and BMI, says the international guideline. It calls for a check at diagnosis, in adults and adolescents alike. After that, the check is repeated every one to three years, depending on other risk factors.

The 75 g oral glucose tolerance test is named as the most accurate test, regardless of BMI. If it cannot be done, fasting glucose or HbA1c can be considered, with significantly reduced accuracy. The guideline does not recommend insulin tests in routine care. When you book, ask whether you need to fast and how long the test takes.

Blood lipids should be measured in all women with PCOS at diagnosis: total cholesterol, LDL, HDL and triglycerides. How often after that depends on the results and your risk. The German guideline names the glucose tolerance test and regular checks of blood pressure and blood lipids, according to the Deutsches Ärzteblatt.

When in your cycle is blood taken for PCOS tests?

The international guideline's recommendations set no fixed cycle day for testosterone. They note that AMH can vary across the cycle. Your doctor decides when you come in for the blood draw. If your period has not come for a long time, there is no fixed cycle day at all. Ask your doctor when to come in and whether you need to fast.

Sam does not suggest a cycle day for a blood draw. The "Your cycles" card in Sam's cycle tracking shows today's day of your cycle, counted from the first day of the last bleed you logged. It does not show an earlier day, such as the day of a past blood draw. If a bleed is missing from your log the number will be off, and every bleed you log counts as the start of a period, also on hormonal medication.

If you take hormonal medication, say so before the blood draw. On combined oral hormonal medication, male hormones are very hard to assess reliably, says the guideline, and AMH can come out lower. Do not change anything without talking to your doctor. For a full list, see what to include on a medication list.

How do you keep PCOS lab reports for later checks?

Earlier reports help because glucose and lipids get checked again. Keep the originals in a folder, or file them in Sam's Health Vault as a photo, scan or PDF.

With your consent, Sam reads the values. Before saving, you check each row and can change the name, value, unit and reference range. Sam matches about 33 lab values by name, including TSH, free T4, glucose, HbA1c, total cholesterol, LDL, HDL and triglycerides. Testosterone, SHBG, LH, FSH, AMH, prolactin, DHEAS and 17-OHP are not among them. For those rows the name, value and unit stay as printed, plus the first reference range your lab printed.

For every value with a printed range, the value card shows "High", "Low" or "In range", worked out against the first printed range only. Some reports print several ranges, for women and men or for different cycle phases. Then the label can be wrong. For rows such as testosterone, LH or FSH it is not an assessment of your results, and a result in range does not rule PCOS out. Some rows also lose their exact name. The glucose results of a tolerance test, such as fasting and after two hours, often all show up as "Glucose". The original report is what counts, and its pages stay in Sam with the values.

You can add a note to each document, such as the cycle day of the blood draw or a hormonal medication. What the values mean is for you and your doctor to discuss.

When should you not wait for PCOS lab results?

A heavy period should be checked by a doctor. Signs, according to Germany's federal health portal: you often need to change a pad or tampon after only one to two hours, or you pass many thick clots. The NHS also lists severe period pain and bleeding between periods or after sex as reasons to see a GP.

Ask for an urgent GP appointment if new thick, dark hair suddenly starts growing on your face and body, your voice is getting lower or your muscles are getting bigger, the NHS says, and do not wait for the lab results. The guideline says signs of raised male hormones that are new and severe, or quickly getting worse, need further tests.

If you go longer than 90 days without a bleed, get it checked by a doctor soon. If you could be pregnant, do not wait that long.

If dizziness, shortness of breath or a racing heart come with heavy bleeding, get medical help the same day. In the UK, contact NHS 111. If the breathlessness is severe, skip this route and call your local emergency number.

Call your local emergency number (112 in the EU, 999 in the UK, 911 in the US) for:

• severe breathlessness, where you are gasping or cannot get words out
• sudden, very severe pain low in the abdomen together with dizziness or fainting
• fainting with chest pain or a racing, pounding or irregular heartbeat
• fainting while exercising or while lying down
• fainting with a serious injury or with a seizure (shaking or jerking)
• fainting where you do not fully recover, or have difficulty speaking or moving afterwards
• someone who is not breathing, or who cannot be woken within a minute, after fainting
• bleeding that cannot be stopped

Do not wait for these to pass. If you have thoughts of harming yourself, call your local emergency number or a crisis line. Samaritans answer on 116 123 in the UK, day and night. In the US, call or text 988, open around the clock. Sam replaces neither an emergency call nor an examination.

Keep your lab reports in Sam and bring them to the appointment

At your next appointment, earlier reports are on your phone, with your lab's first reference range and your note about the blood draw.

• Instead of a folder in a drawer: you file reports as a photo or PDF. With your consent, Sam reads the values, and you check each row before saving.
• Instead of a scribble on the printout: you add a note to each report, such as the cycle day or a hormonal medication.
• Instead of loose numbers: the pages of the original report stay with the values in Sam.

Sam measures no hormones and does not diagnose. The High, Low or In range label is worked out against the first printed range only and is not an assessment; the original report is what counts. More on the PCOS page.

Try Sam for free

Sam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any condition or health state. Always consult qualified professionals for medical decisions.

Related reading

• PCOS: log your cycle and symptoms for the doctor
• Which doctor for PCOS: GP, gynecologist or endocrinologist
• TSH results explained: hypothyroidism and your doctor visit
• Medication list for your doctor: what to include
• Doctor appointment checklist for a chronic condition
• Getting a copy of your medical records when changing doctor

Sources

Updated: October 2026

• Teede HJ et al.: International evidence-based guideline for the assessment and management of polycystic ovary syndrome 2023, summary (PDF). Monash University with ESHRE, ASRM, the Endocrine Society and ESE (diagnosis context statement and recommendations 1.2.1 to 1.2.7, 1.2.10, 1.3.1, 1.3.7, 1.5.1, 1.5.2, 1.5.4 to 1.5.6, 1.8.3, 1.9.1 to 1.9.3, 1.9.9, 1.9.10, 1.9.12)
• Hong AR: Redefining Polycystic Ovary Syndrome: Transformative Diagnostic and Management Changes in the 2023 Guidelines. Endocrinology and Metabolism 2025;40(1):64-66 (figure on the diagnostic algorithm)
• Deutsches Ärzteblatt: New guideline on polycystic ovary syndrome published (German) (13 August 2025; report on the S2k guideline AWMF 089-004, whose full text we could not open in the AWMF register)
• Gloucestershire Hospitals NHS Foundation Trust, pathology: LH and FSH (gonadotrophins) (undated)
• MSD Manual, consumer edition: Absence of menstrual periods (German edition) (fully reviewed August 2025)
• German Federal Ministry of Health, gesund.bund.de: Heavy periods (German) (as of 5 February 2026)
• NHS: Hirsutism (18 August 2025), Heavy periods (19 September 2024), Shortness of breath (30 January 2024), Fainting (17 August 2026), Ectopic pregnancy (23 August 2022)
• British Red Cross: Learn first aid for an adult bleeding heavily
• Samaritans: Contact a Samaritan (call 116 123, 24 hours)
• 988 Suicide and Crisis Lifeline: 988lifeline.org (call or text 988, 24/7)