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Hypothyroidism or underactive thyroid gland has a major impact on a person’s overall health and wellbeing.
Insufficient production of thyroid hormones starts a domino effect or a chain of reactions that affect your quality of life.
Hypothyroidism isn’t just about the thyroid itself, complications associated with this condition are numerous. One of these potential complications is polycystic ovary syndrome (PCOS) which is discussed throughout this post.
Scroll down to learn whether there is, indeed, a relationship between hypothyroidism and PCOS.
What causes PCOS?
Polycystic ovary syndrome is defined as a hormonal disorder that affects women of childbearing age. Figures show that between 5% and 10% of women of childbearing age, i.e. ages 15 to 44, have this hormonal disorder. Women usually find out they have PCOS in their 20s or 30s when they’re experiencing difficulties getting pregnant[i].
PCOS develops due to an imbalance of reproductive hormones which has a negative impact on ovaries which become unable to develop and release an egg needed for ovulation. Some women with PCOS have cysts, but others don’t. Although it’s called POLYCYSTIC ovary syndrome, not all women have multiple cysts.
The exact cause of PCOS is unknown and at this point, it is impossible to pinpoint a trigger behind serious hormonal imbalance. Women with this condition produce higher than normal levels of androgens or male sex hormones.
As a result, their menstrual period becomes irregular and it makes conception more difficult. Low-grade inflammation, family history of PCOS, and excess insulin also play a role in onset this hormonal condition[ii].
Estrogen dominance, a condition that occurs when a person has too high, normal, or even low levels of estrogen but little to no progesterone, can also lead to PCOS problems. In fact, estrogen dominance and PCOS often go hand in hand as one contributes to the other.
Inflammation present in both PCOS and hypothyroidism
Even though inflammation is necessary for wound healing and immune system function, it’s not good in the long run. Persistent inflammation is associated with a wide array of diseases and autoimmune conditions including Hashimoto’s thyroiditis.
Hashimoto’s is an autoimmune disease and the most common cause of hypothyroidism. Gupta G. et al confirmed that hypothyroidism is linked to an inflammatory state as well as dyslipidemia. Their study found that hypothyroid patients have a higher level of inflammatory markers than healthy individuals[iii].
Mancini et al discovered that oxidative stress could be the reason behind inflammation in hypothyroid patients. Oxidative stress and inflammation create a vicious circle while thyroid hormones have a protective role modulating antioxidant levels.
That being said, hypothyroidism can worsen oxidative stress thus aggravating inflammation as well. Same scientists also explained that thyroid function influences activity of ovaries. Free radicals have a physiological role in both hypothyroidism and ovary function which is why low T3 can interfere with antioxidant defenses and induce dysfunction of ovaries[iv].
Just like hypothyroidism, PCOS is also linked with low-grade inflammation. In their study, Kelly et al found that women with PCOS have significantly higher levels of C-reactive protein (CRP), an inflammatory marker, compared to healthy controls. The study also showed that CRP concentrations in women with PCOS strongly correlated with the degree of obesity[v].
As you can see, PCOS and hypothyroidism have a mutual connection – chronic inflammatory state. The two conditions have more in common than most people think. Let’s take a closer look at the relationship between PCOS and hypothyroidism.
How hypothyroidism contributes to PCOS?
Polycystic ovary syndrome and thyroid disorders are the most prevalent endocrine-related problems in general population. Despite the fact that PCOS and hypothyroidism have different etiopathogenesis (the cause and subsequent development) they also have many similarities.
The reality is that PCOS and hypothyroidism have a complex relationship that is not fully elucidated. Underactive thyroid gland influences the morphology of ovaries thus making them become polycystic. Due to the impact of thyroid function on ovaries, disorders affecting the butterfly-shaped gland are one of the exclusion criteria prior to diagnosing PCOS.
How does hypothyroidism lead to polycystic ovaries, you wonder?
Singla et al explained that elevated levels of TRH (thyrotropin-releasing hormone) increase concentration of prolactin and TSH (thyroid-stimulating hormone). Prolactin, a hormone produced by the pituitary gland, plays a role in polycystic ovary morphology by affecting ovulation due to an altered ratio of luteinizing hormone and FSH (follicle-stimulating hormone) and increased concentration of DHEA (dehydroepiandrosterone).
High levels of TSH act on FSH receptors through a spillover effect when seemingly unrelated events in one part of the body can have a huge impact on processes and functions elsewhere. It has also been suggested that hypothyroidism contributes to PCOS through deposition of collagen in ovaries[vi].
Back in 1960 scientists Van Wyk and Grumbach reported that ovarian morphology severity oftentimes depends on gravity and duration of primary hypothyroidism. For example, in the most severe cases of primary hypothyroidism problems affecting ovarian morphology can be mistaken for malignancies.
This unique condition got its name after these scientists and it is called Van Wyk and Grumbach syndrome[vii].
Muderris et al carried out an interesting study whose primary objective was to investigate the relationship of hypothyroidism and PCOS, but also to evaluate the effect of thyroid hormone replacement on ovarian volume. For this purpose, scientists enrolled 26 patients with hypothyroidism who had healthy or polycystic ovaries and 20 controls. Results showed that hypothyroid women had a higher ovarian volume compared to healthy controls. That being said, therapy with levothyroxine decreased the volume of the ovaries.
The study also revealed that hypothyroid women with PCOS had greater levels of testosterone and DHEA which correlates with the fact that this hormonal condition affecting ovaries occurs due to excessive concentration of androgens. Severe and longstanding hypothyroidism not only increases the volume of ovaries but also contributes to cyst formation, scientists concluded[viii].
Role of BMI
A growing body of evidence confirms that prevalence of thyroid disorders, mainly hypothyroidism, increases among women with PCOS.
For example, Sinha et al found a high incidence of autoimmune thyroiditis in PCOS patients which was evidenced by elevated anti-TPO antibody concentration. Scientists revealed that women with PCOS had increased TSH levels compared to controls and some patients also had a goiter[ix].
The study only adds to current evidence that shows a meaningful and complex relationship between two conditions.
Despite the fact that all mechanisms connecting two conditions are not clear, it is believed that body mass index (BMI) has a significant role in the process.
Higher BMI is an integral part of polycystic ovary syndrome. In their study, Lim et al found that ladies with PCOS had a higher risk of overweight, obesity, and central obesity[x]. Same scientists published a separate study which revealed that obesity significantly worsens metabolic and reproductive outcomes in patients with PCOS. Weight treatment and prevention pose as a vital strategy in PCOS management[xi].
Similarly to PCOS, hypothyroidism is also connected with overweight and obesity. In fact, weight gain is one of the most common symptoms of the underactive thyroid gland. Weight gain in hypothyroidism occurs due to several factors. Thyroid hormones control thermogenesis and metabolism and they have a crucial role in lipid and glucose metabolism, food intake and fat oxidation. Dysfunction of thyroid gland decreases thermogenesis and metabolism, thus increasing BMI and leading to overweight and obesity, evidence shows[xii].
Asvold et al found that TSH is higher in people with higher BMI[xiii].
Bearing in mind that both PCOS and hypothyroidism are associated with overweight/obesity and higher BMI, it’s clear that both conditions are connected on a deeper level. Since inflammation plays a role in two conditions, it’s important to mention that obesity increases levels of pro-inflammatory markers.
As a result, this creates a deficiency in T3 hormone parallel with the increase in TSH. Don’t forget that elevated TSH is observed in women with polycystic ovary syndrome.
Insulin resistance is a condition wherein cells fail to respond to insulin. The primary function of insulin is to take in glucose and use it as fuel or stored as body fat. When the body is resistant to insulin, it tries to compensate by producing even more insulin.
This is a serious problem that could lead to type 2 diabetes. In fact, about 70% of people with insulin resistance will develop type 2 diabetes if they don’t change their lifestyle, the Lancet study reported[xiv].
Obesity, a common problem for both hypothyroidism and PCOS, is closely associated with insulin resistance. Evidence shows that overweight leads to insulin resistance through multiple mechanisms including increased oxidative stress, inflammation, mitochondrial dysfunction, among others.
Excessive weight involves chronic low-grade inflammation which makes it difficult for the body to perform various functions including responding to insulin[xv].
Insulin resistance is also a common problem among patients with PCOS. What’s more, a study from the Endocrine Reviews found patients with polycystic ovary syndrome are susceptible to insulin resistance regardless of their weight and BMI and it could be down to an excessive concentration of androgens[xvi].
Furthermore, patients with hypothyroidism are also prone to insulin resistance studies show. The reason behind this relationship is that thyroid dysfunction impairs glucose metabolism[xvii]. This also leads to an increased risk of cardiovascular events.
While the relationship between hypothyroidism and PCOS is complex and more studies are needed to fully understand it one thing is for sure – women with polycystic ovaries should have their thyroid evaluated. The same goes for hypothyroid ladies, you may want to consult your healthcare provider to see whether everything is okay with your ovaries and whether you could be at risk of developing PCOS.
This is particularly important if you’re trying to get pregnant and start a family.
Although both PCOS and hypothyroidism bring many symptoms that you may find uncomfortable, there are many things you can do to manage these conditions. Like hypothyroidism, PCOS also requires a healthy lifestyle and a well-balanced diet. Here are some things you can do to feel better:
- Remove sugar from your diet even if you don’t have insulin resistance
- Avoid inflammatory and strive to consume more anti-inflammatory foods
- Be more active, exercise regularly, move more, but avoid going overboard. Too much exercise can exhibit inflammatory effects. Getting 30-40 minutes of exercise a day is enough and it can help you manage weight
- Decrease consumption of heavily processed and refined foods
- Give a chance to whole foods, fruits, vegetables, and other items that are rich in nutrients
- Stay hydrated
- Adopt healthy cooking methods
Polycystic ovary syndrome affects millions of women who usually find out they have this endocrine condition when they seek doctor’s help due to unsuccessful efforts to get pregnant.
Hypothyroidism can be considered an important cause of PCOS, these two conditions have a rather complex relationship that resides on multiple mechanisms including inflammation, BMI, insulin resistance, elevated TSH, and others.
[i] Polycystic ovary syndrome, WomensHealth.gov https://www.womenshealth.gov/a-z-topics/polycystic-ovary-syndrome
[ii] Polycystic ovary syndrome (PCOS), Mayo Clinic https://www.mayoclinic.org/diseases-conditions/pcos/symptoms-causes/syc-20353439
[iii] Gupta G, Sharma P, Kumar P, Itagappa M. Study on Subclinical Hypothyroidism and its Association with Various Inflammatory Markers. Journal of Clinical and Diagnostic Research : JCDR. 2015;9(11):BC04-BC06. doi:10.7860/JCDR/2015/14640.6806. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4668398/
[iv] Mancini A, Di Segni C, Raimondo S, et al. Thyroid Hormones, Oxidative Stress, and Inflammation. Mediators of Inflammation. 2016;2016:6757154. doi:10.1155/2016/6757154. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4802023/
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[vi] Singla R, Gupta Y, Khemani M, Aggarwal S. Thyroid disorders and polycystic ovary syndrome: An emerging relationship. Indian Journal of Endocrinology and Metabolism. 2015;19(1):25-29. doi:10.4103/2230-8210.146860. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4287775/
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