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Completed

NCT Number: NCT03748966

Calcitriol Monotherapy for X-Linked Hypophosphatemia

Children and adults with XLH recruited will be treated with calcitriol alone (without phosphate supplementation) for one year, during which the calcitriol dose will be escalated during the first 3 months of therapy. The investigators hypothesize that treatment of adults and children with XLH alone will improve serum phosphate levels and skeletal mineralization without causing an increase in kidney calcifications. The study will also examine if calcitriol therapy will improve growth in children.

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Key information

Conditions

X-linked Hypophosphatemia Avitaminosis Bone Diseases Bone Diseases, Metabolic Calcium Metabolism Disorders Congenital, Hereditary, and Neonatal Diseases and Abnormalities Deficiency Diseases Familial Hypophosphatemic Rickets Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Genetic Diseases, Inborn Hypophosphatemia Hypophosphatemia, Familial Hypophosphatemic Rickets Hypophosphatemic Rickets, X-Linked Dominant Kidney Diseases Male Urogenital Diseases Malnutrition Metabolic Diseases Metabolism, Inborn Errors Metal Metabolism, Inborn Errors Musculoskeletal Diseases Nutrition Disorders Nutritional and Metabolic Diseases Phosphorus Metabolism Disorders Renal Tubular Transport, Inborn Errors Rickets Rickets, Hypophosphatemic Urogenital Diseases Urologic Diseases Vitamin D Deficiency

Age range

3 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Early Phase 1

Primary location

Massachusetts General Hospital

Boston, Massachusetts, 02114, United States

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

calcitriol

Drug

Adults and children (age 3-17) with X-linked hypophosphatemia will be treated with calcitriol therapy without phosphate supplementation. Doses of calcitriol will be escalated and optimized in the first three months of the study. Calcitriol is an oral medication taken once a day.

Other names: 1,25 dihydroxyvitamin D

Primary outcomes

  1. Change in Serum Phosphate in Adults and Children With XLH Between Baseline and 12 Months

    Time frame: baseline and 12 months

    serum phosphate

  2. Change From Baseline in TmP/GFR in Adults and Children With XLH

    Time frame: baseline and 12 months

    a measure of kidney resorption of phosphate

  3. Rickets Score for Children With XLH

    Time frame: baseline and 12 months

    a score of rickets severity determined by reading x-rays of wrists and knees (10 point Thacher score with 0 being normal and 10 being severe)

  4. Change From Baseline in Nephrocalcinosis Grade

    Time frame: baseline and 12 months

    determine if there is change in amount of calcifications in the kidneys: graded from grade 0 (normal) to grade IV (stone formation, solitary focus of echos at the tip of the renal pyramid)

Secondary outcomes

  1. Growth in Children With XLH

    Time frame: baseline and 12 months

    Z-score of growth (this is full name of variable)- number represents standard deviation above or below the known mean of the general population at the corresponding age. Z score that is positive is above the mean, negative is below the mean.

Sponsors and collaborators

Lead sponsor

Massachusetts General Hospital

Other

Collaborators

  • National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

Registry information

Official study title

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

Important dates

Study start
2019
Primary completion
2025
Study completion
2026
First posted
Nov 21, 2018
Registry last updated
May 7, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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