Effects of High-dose Radioactive Iodine Therapy on Hormonal Profiles and Sperm Quality in Thyroidectomy Patients

Objectives: This study investigates the effects of high-dose radioactive iodine therapy on gonadotropin and sex hormone levels, and on sperm parameters in male patients with differentiated thyroid carcinoma following thyroidectomy. Methods: Twenty-five male patients (aged 20-60 years) with differentiated thyroid carcinoma underwent thyroidectomy and iodine therapy. The therapeutic dose was 150 mCi of oral sodium iodide solution. Levels of gonadotropins, sex hormones, and anti-Müllerian hormone (AMH) were measured before and two weeks after radioiodine therapy (RT). Semen analysis included liquefaction, odor, color, viscosity, agglutination, and aggregation. The main parameters evaluated were semen volume, pH, sperm count, percentages of motile and progressively motile sperm, round cells, and sperm morphology. Sperm motility, including progressive, non-progressive, and immotile types, and DNA fragmentation were analyzed according to World Health Organization guidelines. Results: The Wilcoxon signed-rank test was used with a significance level of p≤0.05. Follicle-stimulating hormone levels in patients' sera were significantly higher than pre-RIT measurements (p=0.002), whereas luteinizing hormone, dihydrotestosterone, dehydroepiandrosterone sulfate, testosterone, and AMH levels were not significantly different from pre-RT measurements. Total sperm count, volume, motility, and rapid progressive motility increased significantly compared to pre-radioiodine ablation measurements, while other parameters remained unchanged. Conclusion: Male patients who received 150 mCi of radioactive iodine showed no impairment in fertility. Long-term follow-up studies with larger sample sizes are crucial to investigate the physiological roles of gonadal hormones, sperm DNA fragmentation, and AMH in the testes after RIT.