Association of Vitamin D Level and Its Receptor With Endometriosis

Completed

• Conditions: Endometriosis; Vitamin D Deficiency/Insufficiency; Vitamin D Status
• Interventions: Diagnostic Test: Vitamin D level; Other: Vitamin D receptor

• Registration Number: NCT06289257
• Lead Sponsor: Khon Kaen University

Brief Summary

The goal of this cross-sectional prospective matching study is to evaluate whether serum vitamin D levels and vitamin D receptor (VDR) expression are associated with the presence and severity of endometriosis in women of reproductive age.

The main questions it aims to answer are:

* Is there a difference in serum 25-hydroxyvitamin D \[25(OH)D\] levels between women with endometriosis and healthy controls?

* Is there a correlation between serum vitamin D levels and VDR expression in endometriotic tissues?

* Is there an association between vitamin D status and the severity of endometriosis based on the revised American Society for Reproductive Medicine (rASRM) staging?

Researchers will compare participants with endometriosis to matched healthy controls (1:2 ratio).

Participants will:

* Provide blood samples for serum 25(OH)D measurement.

* Undergo surgical tissue sampling (for the endometriosis group) to assess VDR expression using immunohistochemistry staining.

* Complete structured questionnaires regarding sun exposure, lifestyle, and clinical characteristics.

Detailed Description

This cross-sectional study aims to investigate the association between serum vitamin D levels and endometriosis, and to further explore the expression of vitamin D receptor (VDR) in endometriotic tissues using immunohistochemistry.

The study enrolled reproductive-aged women diagnosed with endometriosis who underwent laparoscopic surgery and compared them with matched healthy controls based on age and BMI.

Serum levels of 25-hydroxyvitamin D \[25(OH)D\] were measured using a standardized laboratory assay. Endometriotic tissue samples obtained during surgery were analyzed for VDR expression, qualitative-quantified using the H-score method in both stroma and epithelial compartments. Clinical data, including revised American Society for Reproductive Medicine (rASRM) staging, were used to assess disease severity. Additional data were collected via structured interviews covering sun exposure, reproductive history, lifestyle, and hormonal treatment.

Tissue staining and scoring were reviewed by two blinded pathologists to ensure reproducibility. Data entry validation was performed by cross-checking case report forms with original clinical records, and double data entry methods were used to minimize errors.

Sample size was determined based on prior effect size estimates from published literature, aiming to achieve a power of 80% and significance level of 5%. The study population was sufficient to detect a clinically meaningful difference in vitamin D status between cases and controls.

Missing data were managed using complete case analysis and sensitivity checks. For secondary outcomes, subgroup analyses were conducted based on categorized vitamin D levels (normal, insufficiency, deficiency, severe deficiency).

Statistical analysis included:

* Descriptive statistics for demographic and clinical characteristics.

* Conditional logistic regression or non-parametric equivalents for between-group comparisons.

* Logistic regression models to estimate the odds ratios for severe endometriosis by vitamin D status.

* Correlation analyses between serum vitamin D levels, VDR expression (H-scores), and rASRM scores.

All analyses were performed using STATA version 18.5. The findings aim to clarify the potential role of vitamin D and its receptor in endometriosis pathogenesis and to inform future interventional studies and clinical practice.

Study Timeline

• Study First Submitted: 2024-02-20
• Study First Submitted QC: 2024-02-28
• Study First Posted: 2024-03-01
• Study Start: 2024-05-06
• Primary Completion: 2024-12-23
• Study Completion: 2024-12-23
• Status Verified: 2025-05
• Last Update Submitted: 2025-05-04
• Last Update Posted: 2025-05-07

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 108

Inclusion Criteria

Not provided

Exclusion Criteria

• Received vitamin D supplements within the past 3 months prior to volunteering.
• History of chronic infectious diseases.
• Previously treated for autoimmune diseases.
• History of polycystic ovarian.
• History of bone disorders or receiving medications affecting bones.
• Irregular menstrual cycles or absence of menstruation for more than 3 months up to 1 year.

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Endometriosis	Vitamin D level	Women with endometriosis
Endometriosis	Vitamin D receptor	Women with endometriosis
Control	Vitamin D level	Healthy women

Primary Outcome Measures

Name	Time	Method
Vitamin D level	At enrollment	Vitamin D status

Secondary Outcome Measures

Name	Time	Method
rASRM	Intra operation	Severity of the disease
Vitamin D receptor	Up to 4 weeks after surgery	Tissue staining of Vitamin D antibody

Trial Locations

Locations (1)

Department of Obstetrics and Gynecology, Faculty of Medicine, Khonkaen University; 🇹🇭 Khon Kaen, Thailand