Introduction
Polycystic ovary syndrome (PCOS) is recognized as one of the most common
endocrine disorders in women, causing ovulatory and menstrual
irregularity, infertility, hyperandrogenism, and metabolic dysfunction.
The association of PCOS and autoimmune diseases, especially autoimmune
thyroiditis, is increasingly being recognized. Graves’ disease is an
autoimmune thyroiditis affecting mostly young women, and causes symptoms
such as hyperthyroidism, sweating, heat intolerance, weight loss,
increased appetite, and tremor.(1, 2) Characterized by lymphocytic
infiltration of the thyroid parenchyma, Graves’ disease is found to be
regulated by T helper 1 (Th1) lymphocytes, several cytokines, and
chemokines.(3) Thyrotropin receptor autoantibodies (TRAb) act as the
important indicator of the development of Graves’ disease, which is
often used in clinical assessment.(4, 5) Although the exact pathogenic
mechanism is not fully clear to date, an individual’s genetic
predisposition, interactions between endogenous and environmental
factors, and immune system dysregulation greatly contribute to the onset
of Graves’ disease.(6, 7)
Previous studies showed that patients with PCOS run an elevated risk of
autoimmune thyroiditis compared with those without PCOS.(8, 9) A
previous clinical trial proved a positive relationship between ovary
function, thyroid function, and insulin resistance in women.(10) A
previous systematic review also revealed a higher prevalence of
autoimmune thyroid diseases in patients with PCOS compared with those
without.(11) A Danish cohort study further indicated that patients with
PCOS had a higher risk to develop thyroid diseases.(12) However, only
few pieces of research exclusively explored the association between PCOS
and Graves’s disease. A previous case series of 6 patients indicated a
positive relationship of PCOS and Graves’ disease.(13) A higher
prevalence of serological indicator of Graves’ disease has also been
found in PCOS patients.(14) Since the epidemiology of the relationship
of PCOS and new-onset Graves’ disease hasn’t been well disclosed, we
conducted this original longitudinal nationwide cohort study to explore
this issue.