This study aimed to evaluate hormonal and spermatological parameters associated with male reproductive disorders in patients with thyroid dysfunction. Recent increases in the prevalence of male infertility have highlighted the need for further investigation into the role of the endocrine system, particularly thyroid hormones, in male reproductive health. Thyroid hormones (T3 and T4) are crucial for maintaining spermatogenesis and hormonal balance. According to recent population-based studies, the prevalence of thyroid gland dysfunctions (TGD) ranges between 2% and 6%. [6], while subclinical hyperthyroidism has been reported to occur in 0.5–6.3% of the population [9,10]. In hypothyroidism, reduced levels of thyroid hormones lead to a decrease in serum testosterone concentration, which negatively affects spermatogenesis and deteriorates sperm quality. These alterations manifest clinically as reduced sexual activity, erectile dysfunction, and delayed ejaculation. Conversely, in hyperthyroidism, elevated T4 levels disrupt LH and FSH responsiveness, slow down spermatogenesis, and impair testicular morphology. As a result, sperm count and motility decline, significantly increasing the risk of infertility. Therefore, identifying the relationship between thyroid disorders and male reproductive dysfunction is one of the pressing scientific directions in modern endocrinology and andrology.

This study was conducted at the Republican Specialized Scientific and Practical Medical Center of Endocrinology named after Academician Y.H. Turakulov (Uzbekistan). The study enrolled 21 men aged 25–50 years, including 8 with hypothyroidism and 13 with hyperthyroidism (6 of whom had autoimmune thyroiditis). Five healthy men served as controls. Serum levels of TSH, free T4, total T3, and testosterone, along with semen analysis parameters, were evaluated in all participants.

In the hypothyroidism group, mean TSH levels were 7.9 ± 1.2 mIU/L, testosterone 9.1 ± 1.7 nmol/L, sperm concentration 15.3 ± 5.8 million/mL, and motility 34.6 ± 10.4%. In hyperthyroidism, TSH was 0.09 ± 0.03 mIU/L, testosterone 11.8 ± 2.3 nmol/L, and sperm motility 41.2 ± 12.8%. Among patients positive for anti-TPO antibodies (autoimmune thyroiditis), 68% exhibited oligozoospermia and/or asthenozoospermia. In the control group, mean sperm concentration and motility were 39.8 ± 8.2 million/mL and 58.5 ± 9.7%, respectively (p < 0.01).

The findings demonstrate that thyroid hormonal imbalance significantly impairs male reproductive parameters. In hypothyroidism, reduced testosterone secretion and impaired spermatogenesis are major contributors to infertility. Evaluation of thyroid function should therefore be an integral part of the diagnostic assessment of male reproductive disorders.