Are You One of the 25% of Women with PCOS That Has a Thyroid Condition?

By Clare Goodwin

Last updated: September 3, 2020

PCOS and hypothyroidism. You may not think that they’re linked, but hypothyroidism is actually one of the most common ‘hidden’ causes of PCOS. A quarter of all women with PCOS have a thyroid condition, but this largely goes undiagnosed. According to the Rotterdam Criteria of diagnosis for PCOS, hypothyroidism should be ruled out when you are diagnosed with PCOS. However, in my experience this is rarely happening. In the last week alone, I’ve seen three patients with undiagnosed hypothyroidism. One of them had an extreme case of Hashimoto’s Thyroiditis, an autoimmune condition which will be explained in more detail in this article.

Before we can discuss the relationship between PCOS and hypothyroidism, we need to know what the thyroid is. The thyroid is a gland that sits at the base of your neck and controls how fast or slow your metabolism is. If you have an underactive thyroid (hypothyroidism) then your metabolism will be slower. This will cause you to gain weight, even if you’re on a low calorie diet and a disruption of your sex hormones resulting in infertility. Weight gain and infertility is also a symptom of PCOS. As a result, hypothyroidism often goes undiagnosed in women with PCOS. Other symptoms shared by PCOS and hypothyroidism include:

  • Hair loss
  • Slow metabolism
  • Low mood and depression
  • Fatigue and muscle weakness

Another reason that thyroid conditions are undiagnosed in women with PCOS is because the incorrect tests and reference ranges are used.

How are PCOS and Hypothyroidism Related?

Hypothyroidism (underactive thyroid) occurs when your thyroid isn’t producing enough hormone. Up to a quarter of women with PCOS have hypothyroidism. There are 3 different causes/forms of hypothyroidism:

  1. The thyroid does not produce enough thyroid hormone.
  2. Hashimoto’s Thyroiditis, an autoimmune thyroid condition where the body attacks the thyroid gland.
  3. Low T3 syndrome

Androgens are the main things that links PCOS and hypothyroidism. Hypothyroidism causes increased androgens, which are the main cause of PCOS.  This disruption of sex hormones causes infertility, and studies have shown that up to 25% of women suffering from infertility or repeated miscarriages have hypothyroidism.

How Do You Know If You Have Hypothyroidism?


I’ve detailed some of the general symptoms of hypothyroidism above. Some of the more specific symptoms include:

  • Cold hands and feet
  • Low body temperature
  • Dry, coarse skin and hair
  • Thinning outer third of the eyebrow


Hypothyroidism is diagnosed via a blood test. Unfortunately, the test of the most common measurement for hypothyroidism, Thyroid Stimulating Hormone (TSH), is not very accurate. TSH is a hormone produced in your brain that acts on the thyroid and tells it to produce thyroid hormone. If too little thyroid hormone is produced, then your body will increase TSH to try to produce more of it. It would therefore be expected that TSH levels are a good indicator of whether the thyroid is functioning well or not. However. this is rarely the case.

…and its problems

Studies have shown that inflammatory conditions, such as PCOS, suppress the action of TSH. This means that TSH could be in the normal range, but this doesn’t result in enough thyroid hormone being produced. Another reason why TSH levels are not a good measurement of thyroid function is because the ‘normal’ measurement range is much too high. This week alone I’ve seen three patients that have likely had hypothyroidism for years, but it’s gone undiagnosed for exactly this reason.

Case Example

The most extreme example of this was Emma. She has struggled with her weight for all of her life, even when eating a low calorie diet. When she asked for more tests to find out why she wasn’t losing weight she was told that she just needed to try harder: “PCOS is just an excuse for being fat”. Although higher than what is now deemed as normal, when she was tested her TSH was in the ‘normal’ range, so further testing was refused.


I encouraged her to pay for a full thyroid panel privately (about $150). Her results were pretty astonishing, even to me. As you can see, her thyroid antibodies (indicating Hashimoto’s Thyroiditis) were well above the reference range.


Emma has likely been affected by hypothyroidism for her whole life and it’s possibly the cause her PCOS. About 25% of patients with an autoimmune disease develop other autoimmune diseases. These include rheumatoid arthritis, multiple sclerosis, lupus, inflammatory bowel disease, and many more. It’s really important that people like Emma know this so that they can treat the underlying causes and avoid developing these other conditions.

If you have PCOS or any hypothyroidism symptoms then it’s a very good idea to work with a functional nutritionist or medicine practitioner. This will allow you to get a full panel of thyroid blood tests taken and interpreted.

What Causes Hypothyroidism?

Hypothyroidism can be caused by many things, such as the thyroid gland not be producing enough T4 thyroid hormone. Alternatively, it may be unable to convert T4 into the more active form of thyroid hormone, T3. This is known as low T3 syndrome.

Another form of hypothyroidism, Hashimoto’s Thyroiditis, is an autoimmune condition. Autoimmune conditions occur when the immune system becomes chronically activated. In the case of Hashimoto’s, the body detects the thyroid gland as a foreign invader and begins producing antibodies to attack it. The thyroid gland stops functioning properly as a result.

What is the Best Treatment for Hypothyroidism?

After a diagnosis of hypothyroidism is made, a common treatment is thyroid hormone medication. Although this can be helpful in some situations, it’s not a cure all. The thyroid is either not producing enough hormone or not converting it to the active form. In the case of Hashimoto’s, the thyroid has started attacking itself. Each case of hypothyroidism is unique, so it’s advisable to work with a functional medicine practitioner to fully understand your condition. Nevertheless, no matter what the condition there’s generally some degree of inflammation and there are three ways that this can be reduced.

1. Remove Sugar from Your Diet

‘Fake foods’, especially sugar, cause chronic inflammation, regardless of whether or not you have insulin resistance. One of the ways fake foods cause inflammation is by disrupting your gut bacteria. Your gut bacteria (microbiome) is responsible for 75% of your immune system. If you don’t have the right quantities or strains of good bacteria, or you have an overgrowth of bad bacteria, then this will cause inflammation.

Removing fake foods and replacing them with ‘real’ foods is the first step to reducing inflammation. These foods include vegetables, fruit, protein, and especially fatty fish. Salmon, tuna, and mackerel are all examples of fatty fish and contain omega 3 fats, which are anti-inflammatory.

2. Remove Inflammatory Foods

Your gut doesn’t just host the microbiome of bacteria. It’s also responsible for keeping big proteins out of your body. If you have too much bad bacteria then this can lead to a ‘leaky gut’. This causes inflammation by allowing big proteins, like gluten, to slip through the cell wall and get into your bloodstream.

The biggest offender here is gluten, even if you don’t have celiac disease. Most people don’t realise that 10% of the population have non-celiac gluten sensitivity. This means that they are producing antibodies to wheat and gluten, even if they don’t have celiac disease.

Tests can be done to see if you are producing antibodies. If your doctor won’t do them then they can be ordered privately through a functional medicine practitioner. Alternatively, you can try removing wheat from your diet for 4 months and see if you experience any improvements.

3. Be More Active, But At a Lower Intensity

Both too much or too little high intensity exercise can be inflammatory. Examples of medium to high intensity exercises are running, aerobics, or spin class. If you’re doing any of these for more than 40 minutes each day then this can cause inflammation. This amount of exercise is fine for a lot of people, but if you have an inflammatory condition then it could be doing you harm.

My advice is to be more active, but at a lower intensity. Mix this up with occasional sprinting and resistance exercise 3 times a week. Good ways to introduce low intensity activity into your day include:

  • Actively commuting to work.
  • Going for a walk at lunchtime and during breaks.
  • Meeting friends for a walk, instead of a coffee.
  • Taking up an active hobby, like hiking, surfing, or cycling.

Summary of PCOS and Hypothyroidism:

PCOS and hypothyroidism can frequently occur together. Hypothyroidism is a hidden cause of PCOS. It affects a quarter of all women with PCOS, but often goes undiagnosed. The reason it goes undiagnosed is that the symptoms of PCOS and hypothyroidism are very similar. The TSH measurement for hypothyroidism is also not accurate for women with PCOS.

If you have any symptoms of hypothyroidism, then work with a functional medicine practitioner to make sure that the proper tests are done and that the correct treatment is put in place.

Hypothyroidism comes in many forms and you need to treat the underlying cause of it. One thing you can do to help is reduce inflammation with the following three steps:

  • Remove sugar
  • Remove inflammatory foods
  • Be more active, but at a lower intensity