Overt Versus Subclinical Hypothyroidism in Women with Abnormal Uterine Bleeding: A Prospective Observational Study

Abnormal uterine bleeding (AUB) is a common gynecological problem, and thyroid dysfunction is an important endocrine contributor to menstrual abnormalities.

The objective of this study was to compare the demographic characteristics, menstrual pattern, clinical manifestations, ultrasonographic findings, and laboratory parameters of women with overt hypothyroidism and subclinical hypothyroidism who presented with AUB.

It was a prospective observational study which was carried out in the Department of Obstetrics and Gynecology of a tertiary care hospital from January 2025 to December 2025. Consecutive sampling was used to enroll a total of 252 women with AUB. Clinical, menstrual, ultrasonographic, and thyroid function evaluations were performed on the participants. Serum free T3, free T4, and thyroid-stimulating hormone were determined by chemiluminescence immunoassay.

Of the 252 women with AUB, 33 (13.1%) were diagnosed with hypothyroidism and 40 (15.9%) with subclinical hypothyroidism. The number of women with irregular menstrual cycles was significantly higher in women with hypothyroidism than in women with subclinical hypothyroidism (9 [27.3% vs. 4 10.0%], P = 0.030). Menorrhagia occurred in 18 (54.5%) and 13 (32.5%), respectively, whereas oligomenorrhea occurred in 5 (15.2%) and 15 (37.5%). Lethargy was significantly more frequent in hypothyroidism (22 [66.7%] vs. 14 [35.0%], P = 0.008). Endometrial hyperplasia was seen in 15 (45.5%) and 10 (25.0%), respectively.

Women with AUB who had overt hypothyroidism had more menstrual and clinical features than those who had subclinical hypothyroidism. The results indicate the need for thyroid function assessment in women with AUB, especially when there is menstrual irregularity or clinical features suggestive of thyroid dysfunction.