Thyroid Dysfunction Among Women Presenting with Menstrual Disorders at Kerbala Maternity Hospital, Iraq: A Descriptive Cross-Sectional Study

Background: Thyroid dysfunction may affect menstrual function, but there is little information regarding the pattern of thyroid dysfunction in women who received gynaecological services in Iraq. Objectives: To study the prevalence and type of thyroid dysfunction in women attending the Kerbala Maternity Hospital for menstrual disorders. To assess the impact of thyroid function on regularity of the menstrual cycle and the amount of blood lost during the menstrual cycle, and to assess related sociodemographic and clinical variables. Methods: This single-centre, descriptive cross-sectional study, reported according to STROBE, included 60 non-pregnant women aged 15–40 years with menstrual complaints of at least 3 months and was recruited using non-probability sampling of consecutive outpatients at Kerbala Maternity Hospital between August 2023 and February 2025. Women who had any known thyroid disease and/or drugs known to affect the thyroid were not included. Chemiluminescent immunoassays of fasting serum TSH, fT3 and fT4 were obtained, compared to laboratory reference intervals and reviewed by an endocrinologist. Prevalences are given with Wilson 95% confidence intervals (CI). The associations were tested using the Freeman–Halton exact test, Mann–Whitney and Kruskal–Wallis tests and Spearman correlation; exploratory models were tested using Firth penalised logistic regression. Results: Mean age was 26.9 ± 6.8 years, and 51 women (85.0%) had irregular cycles. Thyroid dysfunction (biochemical) developed in 13 women (21.7%, 95% confidence interval 13.1–33.6): 11 women (18.3%) had hypothyroidism (10 had overt and 1 had subclinical) and 2 women (3.3%) had overt hyperthyroidism. Thyroid status (Freeman–Halton exact p = 0.047) was associated with the distribution of blood-loss categories, as 6 women with thyroid dysfunction (46.2%) reported having severe blood loss. In comparison, 8 women with thyroid dysfunction (61.5%) did not. This finding was not robust because it was not significant after excluding the two hyperthyroid women (p = 0.097) or after excluding women on tranexamic acid and oral contraceptives (p = 0.092), but it was not found to be significant after Holm correction across the five prespecified comparisons (adjusted p = 0.235). TSH, fT3 and fT4 did not differ by cycle regularity (p = 0.756, 0.330 and 0.444). Exploratory analyses showed higher odds of thyroid disease in women with a family history of thyroid disease (odds ratio 4.9; 95% confidence interval 1.4–17.7) and a weak correlation between TSH and BMI (ρ = 0.29). Conclusions: In this sample, biochemical thyroid dysfunction in women with menstrual disorders was more hypothyroid than hyperthyroid, and the incidence of hypothyroidism was about 1 in 5 women. The proposed correlation with heavier periods is tentative and intended to generate hypotheses. More research is needed with a control group, more patients, and objective blood-loss measurement.