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Essential PCOS Blood Tests: A Comprehensive Guide to Diagnosis and Management

Although blood tests are not required for the diagnosis of PCOS, they can help rule out any other hormonal conditions which could be causing your symptoms, as well as give us an idea of what hormonal imbalances are driving your PCOS symptoms. Because there is an increased risk of developing type 2 diabetes and cardiovascular disease, there are certain blood tests that should be done regularly to monitor your risk.

The difficulty can be getting your GP to send you for blood tests, as well as ensuring they send you for the right tests. The aim of this article is to arm you with the correct information to enable you to have informed conversations with your GP about the blood tests that would be most beneficial for you.

Blood test vials

This is by no means an extensive list, there are many other things we can test for with PCOS, however anything more specific will be linked to your symptoms and would need to be discussed with a PCOS specialist or your GP.

These are the tests that I would recommend and/or request on my patients’ behalf:

Tests to exclude other conditions which have similar symptoms:


Elevated prolactin levels can cause irregular periods, which may be mistaken for PCOS symptoms. A prolactin test can help rule out other potential causes of irregular menstruation.

Thyroid function tests

Thyroid disorders can coexist with PCOS and can complicate its management. TSH (Thyroid-Stimulating Hormone), Free T3, and Free T4 should be assessed to rule out thyroid dysfunction.


Requested to rule out adrenal hyperplasia

Tests to confirm diagnosis:

These tests do not NEED to be done to confirm a PCOS diagnosis, but they may be used in certain scenarios.


Elevated testosterone levels can be diagnosed without a blood test by looking at the presence of symptoms such as acne, male pattern hair growth and balding.

The most accurate way to check testosterone levels is to test DHEA-Sulphate. Testosterone levels fluctuate throughout the day and not always giving you an accurate reading. DHEA-S remains the same for a few days and will therefore provide a more accurate reading. Elevated testosterone levels are often the cause of symptoms such as excessive hair growth, acne, and irregular menstrual cycles as it can prevent the maturation of follicles in the ovaries.

Anti-Mullerian hormone

Guidelines now (as of August 2023) recommend that this can be used to diagnose PCOS in place of an intravaginal ultrasound. Anti-Mullerian hormone indicates ovarian reserve and is usually elevated in PCOS.

Other tests to assess hormonal imbalances:

Luteinizing hormone (LH) & Follicle stimulating Hormone (FSH)

These are both involved in ovulation and your ability to fall pregnant. FSH can be low in PCOS and LH can be high, often due to increased insulin and testosterone levels which stimulate the pituitary gland to produce more LH than FSH. High LH levels can prevent regular ovulation. The ratio of these hormones is important, ideally, we are aiming for a ratio of 1:1, we often see ratios of 2:1 or 3:1 (LH to FSH) in women with PCOS.

Liver Function test

If insulin resistance is present and not managed, damage can be caused to the cells of the liver. It is important to check for any damage and help identify whether lifestyle changes need to be made to better manage insulin and glucose levels to prevent further damage to the liver.

C-Reactive Protein (CRP)

This is an indication of inflammation. It is often elevated in PCOS due to chronic low grade inflammation.

Glucose metabolism

It is important to check for prediabetes or diabetes. PCOS increases your risk of developing these conditions so it’s important to pick these up as early as possible to ensure you get the right treatment and manage your lifestyle accordingly. Most GPs will send you for an HbA1c test (this looks at your glucose levels over 3 months) which is great for identifying prediabetes or diabetes, but it does not always show us where there is insulin resistance. Oral glucose tolerance tests are slightly more accurate but not routinely requested as they involve drinking a glucose solution and then having blood tests at regular intervals for 2-3 hours afterward. Ask your GP about both tests, you might get lucky and be able to get both done.

Unfortunately, there is no regular test available to determine insulin resistance, we must rely on reported symptoms for this.


To assess for elevated cortisol levels which is often experienced in PCOS.

Sex Hormone Binding Globulin (SHBG) – This is a protein which plays a role in the regulation of sex hormones and is often disrupted due to PCOS.

Lipid profile

This includes triglyceride levels and cholesterol levels which are important to test due to the increased risk of heart disease.

Estrogen levels

Estradial is used to asses the level of estrogen (female hormones).

When it comes to interpreting your results, it’s important to note that most GPs use predetermined reference ranges to compare your results. Reference ranges are not based on what is considered normal or optimal, instead they are the levels that 95% of the normal population fall into. This includes women of all ages and stages of life, including postmenopausal and those with PCOS (who may have had elevated levels at the time). It is for this reason that women who are clearly showing signs of elevated testosterone levels (excess facial hair, acne) get a ‘normal’ testosterone reading. Be sure to take your results to someone who specialises in PCOS and they will be able to interpret your results correctly.

If you are not getting anywhere with your GP you can request to see another GP. Alternatively, it might be worth working with a health care professional (preferably one that specialises in PCOS) who can communicate with your GP on your behalf and request these blood tests.

If you don’t have any luck with your GP you can request private blood tests through companies like Thriva or Hertility.


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Uncover the 3 simple, highly-effective steps used by myself and all my clients to improve their PCOS symptoms, regain their confidence and live a life they love with PCOS (without dieting). 

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