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PCOS Blood Tests Guide: What to Ask Your GP & How Often (UK)

Updated: Nov 5

When you're living with PCOS, it’s easy to feel unsure about testing - what’s essential, what’s optional, and what to ask for at the GP appointment.


You might be wondering:

  • Which blood tests do I need for PCOS?

  • Has my GP missed anything?

  • How often should I be tested?

  • How do I ask for the right tests confidently?


This guide answers all those questions, with clear, UK-specific, NICE-aligned guidance so you feel informed, supported, and in control of your health.


Blood test vials

Do You Need Blood Tests to Diagnose PCOS?


A PCOS diagnosis is based on symptoms - blood tests are not required to confirm it.


However, blood tests are extremely helpful to:

✅ Rule out other hormone conditions

✅ Understand what’s driving your symptoms

✅ Screen for fertility and metabolic risks

✅ Protect your long-term health

PCOS increases the risk of insulin resistance, type 2 diabetes and cardiovascular disease - so routine testing matters.

The Essential PCOS Blood Tests Checklist (UK)

Tests to Rule Out Other Conditions

These should be carried out during the diagnostic process.

Test

Why it matters

TSH ± Free T4 (Thyroid function)

Thyroid issues can cause irregular periods, fatigue, weight changes.

Prolactin

High levels can cause irregular/absent periods.

17-OHP

Screens for non-classic adrenal hyperplasia (rare, but must be excluded).

Hormone Tests Used in PCOS

Helpful for understanding your hormonal picture - especially for acne, hair growth, hair loss or cycle issues.

Test

Why it matters

Total and/or Free Testosterone

High levels can cause acne, hair growth, hair thinning.

DHEA-S

Helps identify if androgens are coming from adrenal glands.

SHBG

Low in insulin resistance; helps interpret testosterone.

AMH (Anti-Müllerian Hormone)

Often higher in PCOS - can be used instead of ultrasound in adults (per 2023 guideline).

LH and FSH are not routinely recommended for diagnosis - levels can fluctuate and may be misleading.

Metabolic & Long-Term Health Tests

These are essential because PCOS increases metabolic risk.

Test

Why it matters

How often

HbA1c

Screens for pre-diabetes/diabetes

Every 1–3 years (annually if high risk)

Fasting glucose or OGTT

Detects insulin issues more accurately

Ask if TTC or symptoms of insulin resistance

Lipid panel

Checks cholesterol & triglycerides

Every 1–3 years

Liver function test (LFTs)

PCOS increases risk of fatty liver

Every 1–3 years

Vitamin D

Often low in PCOS

Every 6–12 months

If You Take Metformin

Test

Why

Frequency

Vitamin B12

Metformin can lower B12 levels

Annually (NICE-supported)

✅ PCOS Blood Test Checklist Summary

Ask your GP for:

  • Thyroid function (TSH ± Free T4)

  • Prolactin

  • 17-OHP

  • Total ± Free Testosterone

  • DHEA-S

  • SHBG

  • AMH (if no ultrasound done)

  • HbA1c

  • Lipid profile

  • LFTs

  • Vitamin D

  • Vitamin B12 (if taking metformin)


Save this list to your phone for appointments


How Often Should You Have PCOS Blood Tests?

Situation

Recommended frequency

At diagnosis

Full panel

Stable PCOS, low risk

Every 2–3 years

Higher metabolic risk / insulin resistance

Every 12 months

On metformin

Annual B12 + metabolic panel

Trying to conceive

Annual panel or pre-conception check

What to Say to Your GP

It can feel awkward to ask - but you deserve guideline-aligned care.

Try saying:


“Because I have PCOS and the guidelines recommend metabolic monitoring, can we check HbA1c, lipids and liver function?


“I'd also like thyroid function, prolactin and 17-OHP to rule out other causes of my symptoms.”

If they decline, say:


“Could you please record in my notes that I requested these tests and the reason they were not approved?”


This is calm, factual, and protects you - it also encourages clinical accountability.


Private Testing Options (if needed)

You can also access private blood tests through:

Share private results with your GP so they're on your NHS record.


When to See a PCOS Specialist

Consider specialist support if:

  • Your diagnosis feels unclear

  • Your GP won’t run essential tests

  • You’re trying to conceive

  • Your symptoms aren’t improving

  • You want personalised guidance


You don’t have to do this alone - PCOS deserves specialist care.


Need Support Making Sense of Your Results?


If navigating PCOS testing and diagnosis feels overwhelming, my PCOS Initial Assessment & Roadmap session gives you:


  • A full review of your symptoms and history

  • A detailed review of your blood tests

  • Identification of missing tests

  • A personalised nutrition + lifestyle plan

  • GP advocacy support and clear next steps


This session gives you clarity, confidence, and a plan you can trust.

👉 Learn more & book your PCOS Initial Assessment & Roadmap here.


Frequently Asked Questions

Do you need blood tests to diagnose PCOS? No - but they help rule out other causes and check metabolic health.


What blood tests are most important for PCOS? Thyroid, prolactin, testosterone, HbA1c, lipids, liver function and vitamin D.


How often do I need PCOS blood tests? Every 1–3 years, or annually if higher risk or on metformin.


Can PCOS be diagnosed without an ultrasound? Yes — if you meet two of the three Rotterdam criteria.


What if my GP refuses testing? Ask for the refusal to be noted in your record - and request rationale. You an also ask to see another GP for a second opinion.


References

 
 
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