Evaluation Of The Clinical Features Of Infertile Women With Subclinical Hypothyroidism In Relatively High-Iodine-Intake Area

Background: It is well known that hypothyroidism may cause menstrual abnormalities, infertility, increased risk of miscarriage, obstetric complications, and adverse outcomes in offspring. On the other hand, some studies have reported the efficacy of supplementation of levothyroxine (LT4) for subclinical hypothyroidism (SCH) in infertile women. The aim of this study was to evaluate the clinical features of infertile SCH patients in Japan.Methods: A total of 156 SCH patients were enrolled in this study. They were divided into two groups: 76 patients who showed positivity for anti-thyroglobulin antibody (TgAb) and/or thyroid peroxidase antibody (TPOAb) were categorized into group A, while 80 patients who showed negativity for both TgAb and TPOAb were categorized into group B. Between these two groups, we evaluated the following factors: age, thyroid function before treatment, presence of hyperprolactinemia, necessary dose of LT4 for correction of thyroid function, thyroid function after treatment, history of abortion, history of pregnancy after treatment, and dose of LT4 before delivery in pregnant subjects.Results: All of the above investigated factors showed no significant differences between groups A and B. However, a notable point was that the necessary dose of LT4 for correcting thyroid function did not show a significant difference, regardless of anti-thyroid autoantibody.Conclusion: In Japan, an area of high iodine intake, in infertile women with SCH, the administration of an adequate dose of LT4 is recommended, regardless of the presence of chronic thyroiditis.