PCOS Print The Potential Link Between PCOS and Hypothyroidism These two different endocrine disorders share similar features By Nicole Galan, RN facebook twitter linkedin Nicole Galan, RN, is a registered nurse and the author of "The Everything Fertility Book." Learn about our editorial process Nicole Galan, RN Medically reviewed by Medically reviewed by Richard N. Fogoros, MD on January 05, 2019 facebook linkedin Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology. He is Verywell's Senior Medical Advisor. Learn about our Medical Review Board Richard N. Fogoros, MD Updated on November 28, 2019 Polycystic Ovary Syndrome Overview Symptoms Causes Diagnosis Treatment Fertility In This Article Table of Contents Expand PCOS and Hashimoto's Polycystic Ovaries LH-FSH Ratio Obesity Thyroid Autoimmunity View All When investigating the cause of missed or absent periods accompanied by weight gain and/or abnormal hair growth or loss, doctors will consider two diseases associated with hormonal irregularities: polycystic ovary syndrome (PCOS) and Hashimoto's thyroiditis, which is the most common cause of hypothyroidism. Despite their unique biologies, these two conditions share features that suggest a potential link exists between them, albeit one that is complex and not fully sorted out yet. Illustration by Emily Roberts, Verywell PCOS and Hashimoto's Irregular menstrual periods are a hallmark feature of PCOS and occur as a result of increased androgen (male hormone) levels, which prevent regular, monthly ovulation (egg release). Besides irregular menstrual cycles, other potential symptoms of PCOS include excessive facial hair growth, hair thinning, and/or acne. An Overview of PCOS Hashimoto's thyroiditis is the most common cause of hypothyroidism and occurs when your immune system attacks your thyroid tissue. This misguided attack on the thyroid gland impairs the production of thyroid hormone causing symptoms like fatigue, weight gain, hair loss, and irregular menstrual cycles. An Overview of Hypothyroidism Polycystic Ovaries Perhaps the most notable shared feature between PCOS and Hashimoto's thyroiditis is the presence of polycystic ovaries. The term "polycystic" refers to the presence of multiple fluid-filled sacs (cysts) within each ovary. These cysts are actually ovarian follicles that are unable to mature enough to release egg cells. In PCOS, the follicles cannot grow and mature properly due to high androgen levels. In hypothyroidism, hormone changes (specifically, a rise in the level of a hormone called prolactin) prevent ovulation, leading to polycystic ovaries. LH-FSH Ratio Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are two hormones released by the pituitary gland—a pea-sized gland located at the base of your brain. These hormones work to regulate your menstrual cycle. In women with PCOS, the LH-FSH ratio is higher than in women without PCOS. Likewise, research has found that the LH-FSH ratio is higher in people with Hashimoto's thyroiditis. Obesity Thyroid-stimulating hormone (TSH) is higher in people with a high body mass index (BMI). While experts have not fully teased out this association—it may involve the complex workings of inflammatory markers and/or a hormone called leptin—they do know that raised TSH levels lead to the rapid reproduction of fat cells (adipocytes). The Link Between Thyroid Hormones and Weight Likewise, women with PCOS are more likely to be obese or overweight, which may be due to their higher baseline TSH levels. Thyroid Autoimmunity Most women with hypothyroidism from Hashimoto's thyroiditis have elevated thyroid peroxidase (TPO) antibodies and a hypoechogenic thyroids, a pattern seen on ultrasound that is compatible with thyroiditis. Similarly, research has found that women with PCOS have more hypoechogenic thyroids when compared to women without PCOS. Women with PCOS also have higher thyroid antibody levels (for example, TPO antibodies) and are more likely to have a goiter (enlarged thyroid gland). Overall, this scientific data suggest that perhaps PCOS is a type of autoimmune disease or that women with PCOS are more vulnerable to developing autoimmune diseases. A Word From Verywell While the features above suggest a definite link between PCOS and hypothyroidism, exactly what the relationship is, or how it will affect women's care, remains unknown. Regardless, it seems sensible to discuss testing for one condition if you have the other, assuming your doctor has not already done so. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Muscogiuri G et al. 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