Endocrine Abstracts

Introduction: Thyroid hormones play an important role in achieving and maintaining reproductive functions. Thyroid dysfunction affects the menstrual cycle and often leads to menstrual irregularity. We prospectively investigated untreated female patients presenting to our Endocrinology and Internal Medicine outpatient clinics.

Material and methods: All the patients were of reproductive age and were newly diagnosed with thyroid dysfunction. After a detailed history (including menstrual history) was taken, TSH, fT₃, fT₄, anti-Tg, and anti-TPO levels were measured and thyroid ultrasound was performed in all. Thyroid functional status was determined by measurement of TSH, fT₃, and fT₄. Patients were subdivided into the following groups: overt hypothyroidism (54 patients), subclinical hypothyroidism (106 patients), overt hyperthyroidism (50 patients), subclinical hyperthyroidism (55 patients), and euthyroid patients (Hashimoto’s thyroiditis/nodular goiter, 220 patients). Women with normal routine laboratory and imaging studies were classified as controls. Thus, 485 patients and 108 healthy controls were evaluated.

Results: Among patients with overt hypothyroidism, the most frequent menstrual disorders were hypermenorrhea, menorrhagia, oligomenorrhea, and polymenorrhea. Hypermenorrhoea was significantly more common (33.3%) than in controls (5.6%) (P<0.05). Among hypothyroid patients, hypermenorrhoea was more common (35%) in those with severe hypothyroidism (TSH >50 μIU/ml) than in those (16.5%) with mild hypothyroidism (TSH 5–10 μIU/ml) (P<0.05). The prevalence of menstrual disturbances in the other groups of thyroid dysfunction patients was not significantly different than that of controls.

Conclusion: Thyroid function influences the menstrual cycle and affects reproductive activity, fertility, and pregnancy outcomes. For these reasons, investigation of thyroid function in women with abnormal menstrual activity should be performed.