Frequencies of thyroid-related diagnoses and dyslipidemia among Japanese women with menstrual-related disorders aged under 40 years: A nationwide cross-sectional study using health insurance claims data.

Authors

Tatsuya Yoshihara, Yosuke Ono, Harumasa Arita, Akiko Nakagomi, Dai Miyashita, Kota Tanaka, Satoko Sasatsu, Osamu Yoshino

Published in

PloS one. Volume 21. Issue 10. Pages e0361575. Epub Oct 30, 2026.

Abstract

Women with endometriosis and dysmenorrhea are increasingly recognized as having systemic comorbidities beyond pelvic disease, but large-scale data on endocrine and metabolic comorbidities across a broad menstrual-related disorders population remain limited. Using the Japan Medical Data Center Claims Database, we conducted a nationwide cross-sectional study of women aged under 40 years enrolled in 2023. Women with confirmed diagnoses of endometriosis (ICD-10: N80) and/or dysmenorrhea (N94.4 or N94.6) were classified as the menstrual-related disorders group (n = 257,897); those without such diagnoses were the control group (n = 3,183,032). The primary outcomes were the frequencies of thyroid-related diagnoses (hypothyroidism [E03], non-toxic goiter [E04], hyperthyroidism [E05], thyroiditis [E06], and other thyroid disorders [E07]) and dyslipidemia (E78). Stratified analyses were performed according to prescription for low-dose estrogen-progestin preparations (LEP) or dienogest (DNG). All thyroid-related diagnoses were recorded more frequently among women with menstrual-related disorders than among controls. Hypothyroidism was identified in 2.1% of women with menstrual-related disorders versus 0.8% of controls (prevalence ratio [PR] 2.46; 95% CI 2.39-2.54); the corresponding PR was 3.11 (95% CI 2.99-3.24) in the endometriosis subgroup (n = 96,863). Dyslipidemia was recorded in 5.2% of women with menstrual-related disorders versus 1.4% of controls (PR 3.73; 95% CI 3.66-3.80; prevalence difference +3.78 percentage points). The endometriosis subgroup consistently showed the highest frequencies. These associations remained statistically significant after adjustment for age using the Mantel-Haenszel method (adjusted PR 1.45-3.02 across all comparisons), although adjusted estimates were consistently lower than crude estimates. Among women with menstrual-related disorders, hypothyroidism was more frequent in those without LEP/DNG prescriptions (3.4%) than in those with prescriptions (1.5%), whereas dyslipidemia frequencies were similar (5.2% vs. 5.1%). These findings indicate that young Japanese women with menstrual-related disorders have substantially higher frequencies of thyroid-related diagnoses and dyslipidemia than controls, particularly those with endometriosis. Surveillance bias, age confounding, and confounding by indication cannot be excluded because of the cross-sectional claims-based design.

PMID:
42961921
Bibliographic data and abstract were imported from PubMed on 31 Oct 2026.

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