Impact of Laboratory-Measured Euthyroid Hashimoto's Thyroiditis on Reproductive Hormone Profile in Women with Obesity.

Introduction: Hashimoto's thyroiditis is a common endocrinological disorder that often coexists with obesity. Thyroid hormones interact with the regulation of sex steroids, and thyroid autoimmunity has a negative impact on female fertility. There are studies showing when euthyroid state is achieved with hormone replacement therapy (HRT), the reproductive hormone profile is improved but they usually compare the reproductive hormones before and after HRT in the same individuals. Studies comparing patients with Hashimoto's thyroiditis in an euthyroid state receiving HRT with individuals having normal thyroid function are limited. Here, it was aimed to search the impact of euthyroid Hashimoto's thyroiditis on reproductive hormone profile in women living with obesity. Materials and Methods: Sixty-one randomly selected female patients with Hashimoto's thyroiditis were included as the case group and 60 patients without Hashimoto's thyroiditis were included as the control group, from our obesity center. The case group included patients who had menstrual cycles and were euthyroid under l-thyroxine treatment for at least 6 months. Data on weight, height, body mass index (BMI), waist circumference (WC), free thyroxine (fT4), thyroid stimulating hormone (TSH), thyroid peroxidase antibody (anti-TPO), cortisol, insulin, prolactin (PRL), follicular stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E₂), progesterone (prog), testosterone (T), and dehydroepiandrosterone sulfate (DHEAS) levels, l-thyroxine treatment dosage (for case group), and accompanying diseases were recorded. The results were evaluated using SPSS. Results: A total of 121 patients were included in the study. Mean age was 41.8 ± 8.5 years in case and 38.6 ± 8.9 years in control group. There was no significant difference in weight, height, BMI, WC, or accompanying diseases between Hashimoto's thyroiditis and control group. fT4, anti-TPO, cortisol levels were higher in Hashimoto's thyroiditis group when compared with control group, but there was no significant difference for TSH, insulin, FSH, LH, E₂, prog, T, DHEAS, or PRL. Conclusion: In women living with obesity, it is important to screen for Hashimoto's thyroiditis and achieve euthyroidism through effective LT4 treatment to promote a healthy reproductive system and improve fertility rates.