Analysis of Vitamin D and VDR Expression in Endometriosis: A Case-Control Study

July 1, 2025 updated by: Vitet Layanun, Khon Kaen University

Analysis of Vitamin D and VDR Expression in Women With Advanced Endometriosis: A Case-Control Study in Thailand

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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

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 Type

Observational

Enrollment (Actual)

108

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Thailand
      • Khon Kaen, Thailand, 40000
        • Department of Obstetrics and Gynecology, Faculty of Medicine, Khonkaen University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Thai women, reproductive age

Description

Inclusion Criteria Endometriosis Group:

  • Women diagnosed with ectopic endometriotic tissue:
  • Have a scheduled surgery appointment at Sri Nakarin Hospital.
  • Are aged 18 years or older.

Inclusion Criteria Control Group:

  • Women undergoing examination at the outpatient department of Sri Nakarin Hospital.
  • No history of gynecological diseases or previous treatment for gynecological conditions associated with lower abdominal pain, infections, or abdominal masses at present.
  • Have undergone a gynecological examination within the past year, or if examined during the current visit, the results were normal.
  • Have undergone an ultrasound examination within the past year, or if examined during the current visit, the ultrasound results were normal.

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 Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Endometriosis
Women with endometriosis
Diagnostic test: Vitamin D level
Vitamin D level in blood
Other Names:
  • Vitamin D status
Other: Vitamin D receptor
Vitamin D receptor in endometriosis tissue
Control
Healthy women
Diagnostic test: Vitamin D level
Vitamin D level in blood
Other Names:
  • Vitamin D status

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Vitamin D level
Time Frame: At enrollment
Vitamin D status
At enrollment

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
rASRM
Time Frame: Intra operation
Severity of the disease
Intra operation
Vitamin D receptor
Time Frame: Up to 4 weeks after surgery
Tissue staining of Vitamin D antibody
Up to 4 weeks after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Khon Kaen University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 6, 2024

Primary Completion (Actual)

December 23, 2024

Study Completion (Actual)

December 23, 2024

Study Registration Dates

First Submitted

February 20, 2024

First Submitted That Met QC Criteria

February 28, 2024

First Posted (Actual)

March 1, 2024

Study Record Updates

Last Update Posted (Actual)

July 4, 2025

Last Update Submitted That Met QC Criteria

July 1, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • HE661574

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Follow the Center for Ethics in Human Research, Khon Kaen University submission.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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