PCOS The Potential Link Between PCOS and Hypothyroidism These two different endocrine disorders share similar features By Nicole Galan, RN Nicole Galan, RN Facebook LinkedIn Twitter Nicole Galan, RN, is a registered nurse and the author of "The Everything Fertility Book." Learn about our editorial process Updated on November 04, 2022 Medically reviewed by Renita White, MD Medically reviewed by Renita White, MD LinkedIn Renita White, MD, FACOG, is a board-certified obstetrician/gynecologist who practices at Georgia Obstetrics and Gynecology. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents PCOS and Hashimoto's Polycystic Ovaries LH-FSH Ratio Weight and PCOS Thyroid Autoimmunity When investigating the cause of missed or absent periods accompanied by weight gain and/or abnormal hair growth or loss, healthcare providers 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 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. With hypothyroidism, the main hormone change is the decreased amount of thyroid hormone. That leads to a chain of events that include variations in prolactin, but it important to explain that it all stems from low thyroid hormone. Especially when there is another condition (hyperprolactinemia) that is due to high prolactin. 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 people with PCOS, the LH-FSH ratio is higher than in those without PCOS. Likewise, research has found that the LH-FSH ratio is higher in people with Hashimoto's thyroiditis. Weight and PCOS Thyroid-stimulating hormone (TSH) is higher in people who are considered overweight. 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 Relationship Between Thyroid Hormones, Metabolism, and Weight Likewise, those with PCOS are more likely to be overweight. 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 those 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). There is some data to suggest 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 care, remains unknown. Regardless, it seems sensible to discuss testing for one condition if you have the other, assuming a healthcare provider has not already done so. 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. High-normal TSH values in obesity: is it insulin resistance or adipose tissue's guilt? Obesity (Silver Spring). 2013 Jan;21(1):101-6. Danfeng D, Xuelian L. The relationship between thyroiditis and polycystic ovary syndrome: a meta-analysis. Int J Clin Exp Med. 2013;6(10):880-9. Gaberscek S, Zaletel K, Shwetz V, Pieber T, Obermayer-Pietsch B, Lerchbaum E. Mechanisms in Endocrinology: Thyroid and polycystic ovary syndrome. Eur J Endocrin. 2015; 172: R9-R21. Singla R, Gupta Y, Khemani M, Aggarwal S. Thyroid disorders and polycystic ovary syndrome: An emerging relationship. Indian J Endocrinol Metab. 2015 Jan-Feb; 19(1):25-9. doi: 10.4103/2230-8210.146860 McCance, K. and Huether, S. (2016) Understanding Pathophysiology (Sixth Edition). St. Louis, Missouri: Mosby. By Nicole Galan, RN Nicole Galan, RN, is a registered nurse and the author of "The Everything Fertility Book." See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit