Treatment of X-Linked Hypophosphatemia with Calcitriol

Calcitriol Monotherapy for X-Linked Hypophosphatemia: Effects on Mineral Ions, Growth and Skeletal Parameters

Early Phase 1 Interventional Massachusetts General Hospital · NCT03748966

This study tests if using calcitriol alone for a year can help children and adults with X-Linked Hypophosphatemia improve their phosphate levels and bone health without adding extra phosphate.

Quick facts

PhaseEarly Phase 1
Study typeInterventional
Enrollment20 (estimated)
Ages3 Years to 70 Years
SexAll
SponsorMassachusetts General Hospital Academic / other
Locations1 site (Boston, Massachusetts)
Trial IDNCT03748966 on ClinicalTrials.gov

What this trial studies

This study involves treating children and adults diagnosed with X-Linked Hypophosphatemia (XLH) using calcitriol alone for one year, without phosphate supplementation. The treatment will begin with an escalating dose of calcitriol over the first three months. The goal is to improve serum phosphate levels and skeletal mineralization while monitoring for kidney calcifications. Additionally, the study will assess the impact of calcitriol on growth in children with XLH.

Who should consider this trial

Good fit: Ideal candidates include children and adults with a clinical diagnosis of XLH and specific serum and genetic criteria.

Not a fit: Patients with known allergies to calcitriol or those currently using certain medications that affect mineral handling may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could significantly improve phosphate levels and bone health in patients with XLH.

How similar studies have performed: While this approach is novel in its exclusive use of calcitriol without phosphate supplementation, similar studies have shown promise in managing XLH.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Clinical diagnosis of XLH with family history excluding male-to-male transmission, or positive genotype for PHEX mutation
* Serum PTH levels less than 1.5x the upper limit of normal
* Serum calcium levels less than 10.0 mg/dl
* eGFR \>= 60 mL/min/1.73m2
* 25(OH) vitamin D level \>= 20 ng/dL

Exclusion Criteria:

* Known allergy to calcitriol
* Pregnancy or breast feeding
* Use of skeletally active agents such as bisphosphonates, teriparatide, SERMS, hormone replacement therapy and progesterone-only contraceptive agents (combination oral contraceptive use in premenopausal women is not an exclusion criterion).
* Unwilling or unable to stop therapy with calcitriol and phosphate therapy for two weeks prior to study
* Therapy with cinacalcet within the past two weeks
* Current use of growth hormone therapy
* Use of diuretics or medications that alter renal handling of mineral ions.
* Use of glucocorticoids for more than 14 days in the past 12 months with the exception of inhaled agents.
* History of malignancy except basal and squamous cell carcinoma of the skin.
* Significant history of psychiatric disease per DSM-5.
* Substance use disorder per DSM-5.
* Significant cardiopulmonary disease (unstable CAD or stage D ACC/AHA heart failure).
* Absence of laboratory values for serum calcium, phosphate and creatinine in the 24 months prior to enrollment.

Where this trial is running

Boston, Massachusetts

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions X-linked HypophosphatemiaHypophosphatemic RicketsHypophosphatemic Rickets, X-Linked DominantXLHcalcitriolx-linked hypophosphatemiarickets1,25 dihydroxyvitamin D
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.