PCOS and hyperthyroidism involve the overproduction of certain hormones. Although the two conditions can occur at the same time, they don’t cause one another.

Although PCOS and hyperthyroidism can produce some of the same symptoms — like thinning hair, menstrual irregularities, and weight fluctuations — how they do so differs.

Hyperthyroidism occurs when your thyroid gland produces more hormones than your body needs.

Thyroid hormones help regulate your energy levels, hair growth, weight, and more. Higher than expected levels can increase your metabolism, resulting in unexpected weight loss, an irregular heartbeat, and hand tremors.

PCOS, on the other hand, can cause your ovaries to produce unusually high levels of androgens like testosterone, and unusually low levels of estrogen and progesterone.

Estrogen and progesterone regulate the menstrual cycle and facilitate reproduction, explains Amy Myers, MD, author of “The Thyroid Connection” and “The Autoimmune Solution.” Low levels can lead to irregular menstrual cycles, missed periods, and unpredictable ovulation.

“Research has found that thyroid disorders are more common in people with PCOS,” said hormone specialist and integrative nutritionist Alisa Vitti, author of “In the FLO” and “WomanCode.”

It’s thought that the entire endocrine system is interconnected. When one hormone becomes imbalanced, the others are more likely to fluctuate, too, explains Kris Adair, family nurse practitioner and founder of Adair Family Clinic and MedSpa in Peoria, Arizona.

That said, people are more likely to have PCOS and hypothyroidism (underactive thyroid) than PCOS and hyperthyroidism (overactive thyroid), according to Vitti.

If you receive a PCOS diagnosis, many healthcare professionals will check your thyroid activity and prolactin levels to determine if you also have hyperthyroidism or hypothyroidism.

Unfortunately, we still don’t know conclusively what causes PCOS, says Adair.

There has been some research, she notes, that suggests the following may increase your risk of PCOS:

When your cells don’t respond to insulin, Myers explains, they can’t use glucose for energy. Your pancreas may increase insulin production to compensate.

This can increase the production of androgenic hormones, often resulting in PCOS. “High levels of androgens prevent the ovaries from producing estrogen and progesterone,” Myers said.

The reason that autoimmune disorders and diet may affect your PCOS risk may come down to inflammation.

“Research suggests that chronic low-grade inflammation contributes to the development of PCOS,” said Myers.

The most common cause of hyperthyroidism is an autoimmune condition called Graves’ disease. This condition causes your immune system to see your thyroid gland as an invader and attack it.

Overactive thyroid nodules and thyroiditis can also cause hyperthyroidism.

Generally speaking, hyperthyroidism is more common among people who have one or more of the following:

You might be more likely to develop hyperthyroidism if you consume a large amount of iodine (in food or medication) or use nicotine products, adds Vitti.

There isn’t a cure for PCOS, but there are treatments that can help manage your symptoms.

Doctors and other healthcare professionals may prescribe one or more of the following for PCOS:

Functional medicine specialists, notes Myers, may prescribe adaptogenic blends instead.

“Many providers also recommend changing your lifestyle to reduce inflammation,” said Myers.

These changes usually include:

“Sometimes providers will recommend a 30-day elimination diet that involves removing gluten, grains, and legumes, taming the toxins, and healing systemic inflammation,” she said.

“Finding the right treatment protocol can often be a case of trial and error, as you learn what medication or combination of medications, and at what doses, work best for you,” said Myers.

Hyperthyroidism can be cured in one of two ways.

The first is the total removal of the thyroid gland through surgery. Once the gland is gone, you’ll take lifelong thyroid replacement medications.

Some people opt to do radioactive iodine treatment instead. This treatment involves drinking or ingesting a mixture of iodine and a low dose of radiation to destroy thyroid cells.

Hyperthyroidism can also be managed long term with medication to stop the thyroid from producing excess hormones (thionamides) and to help alleviate symptoms (beta-blockers).

If any of the aforementioned symptoms resonate, Myers recommends working with a healthcare professional.

They can perform a blood test to discern which (if any) of your hormones are being produced in excess.

If your androgen levels are high — which suggests that you may have PCOS — a healthcare professional may also perform a pelvic ultrasound to look for ovarian cysts.

If your thyroid hormones are high, a healthcare professional may suggest a thyroid scan to rule out other conditions that could cause the thyroid to produce these hormones in higher quantities.

Depending on your final diagnosis, the healthcare professional will work with you to develop a care plan best suited to your individual needs.

Does PCOS cause hyperthyroidism?

No, PCOS does not cause hyperthyroidism.

“Hyperthyroidism is caused by Graves’ disease, consuming too much iodine, nodules on the thyroid, thyroiditis, and family history,” said Vitti. “PCOS is not caused by the same things.”

Does hyperthyroidism cause PCOS?

No, hyperthyroidism does not cause PCOS.

Although the two conditions are linked, available research says, “The exact nature of this link has not been elucidated yet.”

Can you have PCOS and hyperthyroidism at the same time?

Yes. Research shows that thyroid disorders like hyperthyroidism are more common in women with PCOS than in people without PCOS.

Can one condition be mistaken for the other?

“Both can cause thinning hair, missed or irregular periods, very light periods, and weight fluctuations,” explained Myers. Both also sometimes cause polycystic ovaries. As such, the two could be mistaken for one another.

“It can be hard to determine which one it is with just a health history review,” said Adair. “But the right provider will evaluate a patient for both conditions simultaneously with lab testing and appropriate diagnostics to determine the final diagnosis.”

PCOS and hyperthyroidism are two completely different conditions, though they do share many of the same symptoms. Without a full checkup by a healthcare professional, one can be mistaken for the other.

Gabrielle Kassel (she/her) is a queer sex educator and wellness journalist who is committed to helping people feel the best they can in their bodies. In addition to Healthline, her work has appeared in publications such as Shape, Cosmopolitan, Well+Good, Health, Self, Women’s Health, Greatist, and more! In her free time, Gabrielle can be found coaching CrossFit, reviewing pleasure products, hiking with her border collie, or recording episodes of the podcast she co-hosts called Bad In Bed. Follow her on Instagram @Gabriellekassel.