Abstract
Background Hyperthyroid females often complain of menstrual disturbances and impaired fertility. This study was designed to observe the effect of hyperthyroidism on ovarian folliculogenesis and the hypophyseal-gonadal axis. Methodology Adult female Wistar albino rats (n= 12), six to eight weeks of age, and weighing 70-162 g, were divided randomly into control (Group A) and experimental (Group B) groups. Group A received daily intraperitoneal injections of 250 µL normal saline (10 µL 5 µM NaOH dissolved in it) for 14 days. Group B received a daily intraperitoneal injection of levothyroxine (600 µg/kg body weight) to induce hyperthyroidism. Rats were weighed at the start and the end of the experimental period on the day of sacrifice. Results Statistical analysis of the data revealed successful induction of hyperthyroidism in Group B as their thyroid-stimulating hormone (TSH) levels decreased significantly. The ovarian size was significantly reduced in the hyperthyroid group (p < 0.029). There was a significant decrease in thickness of the ovarian capsule (p < 0.000), an increase in the number of primordial, primary, and secondary follicles (p < 0.001, 0.000, and 0.001, respectively), and a decrease in size of primary and secondary follicles (p < 0.041 and 0.020) in the hyperthyroid group. Conclusion Hyperthyroidism can affect ovarian cytoarchitecture, probably by acting directly on its receptors and thus affects female fertility.