Free vitamin D and steroid metabolism in endocrine and kidney conditions

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This observational study collects blood samples from adults across several cohorts (healthy controls, people with obesity, chronic kidney disease stage ≥3a, first-trimester pregnancy, primary hyperparathyroidism scheduled for surgery, and complex calcium/phosphate disorders) to measure free and total vitamin D and related steroid markers. Laboratory assays will quantify free vitamin D, total vitamin D, vitamin D binding protein, and selected steroid metabolites to characterize binding and metabolic patterns. The study compares these measures between groups to determine whether total vitamin D testing reflects biologically available free vitamin D in different clinical contexts. Findings are intended to clarify how vitamin D results should be interpreted in pregnancy and in various endocrine and renal disorders.

Why it matters

Who can join: the full rules

1. General inclusion Criteria:

   \- 18 years or above
2. General exclusion Criteria:

   * Below 18 years of age
   * Individuals incapable of providing informed consent
3. Cohort inclusion criteria

   * Obesity: BMI ≥ 25 kg/m2
   * Chronic Kidney Disease: ≥ CKD stage 3a (eGFR \< 60 mL/min/1.73m2)
   * Pregnancy: in trimester 1 of pregnancy
   * Primary hyperparathyroidism: diagnosis at UZ Leuven and scheduled for parathyroidectomy at UZ Leuven
   * Complex calcium and phosphate disorders: diagnosis at UZ Leuven
4. Cohort exclusion criteria

   * Healthy controls: BMI below 18 kg/m² or above 25 kg/m², pregnancy, chronic kidney disease (independent of staging), primary hyperparathyroidism and vitamin D and/or calcium supplementation
   * Obesity: chronic kidney disease (independent of staging), pregnancy, primary hyperparathyroidism
   * Chronic Kidney Disease: BMI below 18 kg/m² or above 30 kg/m², pregnancy, primary hyperparathyroidism
   * Pregnancy: BMI below 18 kg/m² or above 30 kg/m², chronic kidney disease (independent of staging), primary hyperparathyroidism
   * Primary hyperparathyroidism: BMI below 18 kg/m² or above 30 kg/m², pregnancy, chronic kidney disease (independent of staging), secondary hyperparathyroidism

Where it's running

• University Hospitals Leuven
  Leuven, Belgium Recruiting

Study contacts

• Principal investigator: Leen Antonio, MD, PhD — University Hospitals Leuven, Department of Endocrinology
• Study coordinator: Nick Narinx, MD
• Email: nick.narinx@uzleuven.be
• Phone: +3216348516

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.