Assessment of Stromal Calretinin Expression in Normal and Pathological Endometrium of Patients With Abnormal Uterine Bleeding.

BACKGROUND

Abnormal uterine bleeding (AUB) is a prevalent gynecological issue, often arising from structural or functional endometrial abnormalities. Calretinin, a calcium-binding protein, has demonstrated diagnostic relevance in various tissues; however, its role in endometrial stroma remains insufficiently explored. This study was conducted to evaluate calretinin expression in normal and pathological endometrial tissues associated with AUB.

MATERIALS AND

METHODS

A prospective observational study was conducted on 60 endometrial samples (normal and AUB-associated lesions) over two years from June 2023 to March 2025. Histopathological evaluation was followed by immunohistochemistry for stromal calretinin using a semi-quantitative score (0-5+). Statistical analysis was performed using IBM SPSS Statistics v25.0 (IBM Corp., Armonk, USA), including analysis of variance (ANOVA), Tukey's post hoc test, and Pearson's correlation.

RESULTS

Normal endometrium (notably secretory and proliferative phases) exhibited higher stromal calretinin expression (mean scores: 3.0 and 2.0, respectively), while lesions such as adenomyosis, endometrial polyps, hyperplasia, and carcinoma demonstrated markedly reduced or absent expression. A statistically significant difference in calretinin scores was found across different histopathological categories (p=0.0002). A moderate negative correlation (r=-0.43) was observed between calretinin expression and pathological endometrial states.

CONCLUSION

Stromal calretinin expression was substantially reduced in AUB-related endometrial lesions compared to normal endometrium. These findings suggest its potential utility as a supplementary biomarker for distinguishing between physiological and pathological endometrial conditions. Further large-scale studies are warranted to validate its diagnostic and prognostic significance.