Effectiveness of Paricalcitol in Reducing Parathyroid Hormone Levels in X-linked Hypophosphatemic Rickets

This study has been completed.
Information provided by (Responsible Party):
Thomas Carpenter, Yale University
ClinicalTrials.gov Identifier:
First received: December 28, 2006
Last updated: January 29, 2013
Last verified: January 2013

The purpose of this study is to determine the effectiveness of paricalcitol, a form of synthetic vitamin D, in lowering parathyroid hormone (PTH) levels and reducing disease symptoms in children and adults with X-linked hypophosphatemic (XLH) rickets.

Condition Intervention Phase
Hypophosphatemia, Familial
Drug: Paricalcitol
Other: Placebo
Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: The Role of Parathyroid Hormone in the Pathogenesis of Skeletal Disease in X-linked Hypophosphatemic Rickets (XLH)

Resource links provided by NLM:

Further study details as provided by Yale University:

Primary Outcome Measures:
  • Peak PTH and area under the curve for PTH measurement [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]
  • Change in a modified XLH Disease Index (XDI) [ Time Frame: Measured at Month 12, compared with baseline ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Clinical parameters of height and blood pressure [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]
  • Static parameters of serum alkaline phosphatase, CTx (resorption marker), PINP (bone turnover marker), 25-OH vitamin D, FGF7, FRP4 and MEPE (potential disease mediators), urinary calcium excretion, and TMP [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]
  • Diurnal measure including serum Ca, P, PTH, 1,25 vitamin D, and FGF23 (intact and C-terminal) [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]
  • Repeat bone scan [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]
  • Repeat cardiac sonogram [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]
  • Clinical questionnaire, SF-36v2 [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]
  • Overall disease score on XDI [ Time Frame: Measured at baseline and Month 12 ] [ Designated as safety issue: No ]

Enrollment: 34
Study Start Date: January 2007
Study Completion Date: August 2012
Primary Completion Date: August 2012 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1
Participants given active drug, paricalcitol (Zemplar), in effort to reduce PTH level
Drug: Paricalcitol
Paricalcitol given first as a dose of 2 capsules once per day. Dose titration as needed per biochemical results at outpatient visits.
Other Name: Zemplar
Placebo Comparator: 2
Participants given placebo capsule to match for comparison
Other: Placebo
Placebo sugar pill

Detailed Description:

XLH rickets is a rare inherited disorder in which the bones become painfully soft and bend easily because of a phosphate deficiency. This genetic defect causes the kidneys to allow excretion of an inappropriately high amount of phosphate into the urine. The kidneys are also unable to convert vitamin D into a form usable by the body, resulting in inadequate amounts of active vitamin D. Because vitamin D is needed to absorb calcium and phosphate from the intestine, this deficiency further reduces phosphate levels. Without the sufficient phosphate needed for normal bone growth, individuals with XLH rickets typically develop skeletal malformations, bone pain, and abnormally bowed legs. Hyperparathyroidism, a condition in which the parathyroid glands excrete excess amounts of PTH, also occurs frequently in individuals with XLH rickets, and may play a significant role in the skeletal complications associated with XLH rickets. The purpose of this study is to determine the effectiveness of paricalcitol in lowering PTH levels and reducing disease symptoms in individuals with XLH rickets.

This study will last 12 months. Participants will be randomly assigned to receive either paricalcitol or placebo, taken in the form of two pills daily for the duration of the study. During a baseline 3-day inpatient hospital stay, participants will undergo a physical exam, a cardiac ultrasound, a bone scan, blood collection, and a radiographic skeletal survey. The skeletal survey will include x-rays of various body parts. Participants who are 18 years or younger will not undergo the radiographic skeletal survey. Study visits for all participants will occur every 2 months until the end of the study. These visits will include a physical exam, review of disease symptoms, blood and urine collection, and a check of medication compliance.


Ages Eligible for Study:   9 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Diagnosis of XLH rickets
  • Fasting serum calcium of 10.7 mg/dl or less
  • Fasting PTH greater than 40 nleq/ml and less than 120 nleq/ml in the mid-molecule PTH assay at screening (upper limit of normal is 25 nleq/ml)
  • Willing and able to participate in the trial
  • Taking stable dose of standard therapy for XLH rickets for at least 2 months prior to study entry
  • Concomitant therapy for XLH rickets will not be an exclusion criteria
  • Parent or guardian willing to provide informed consent, if applicable

Exclusion Criteria:

  • Concomitant kidney failure (estimated creatinine clearance less than 60 cc/min or serum creatinine greater than 1.5 mg/dl)
  • Serum 25-OH vitamin D less than 20 ng/ml. Participants meeting this criterion will receive vitamin D3 supplementation for 3 months and then be rescreened.
  • Unable to comply with protocol and appropriate follow-up visits
  • Treatment with agents that may affect skeletal metabolism, such as glucocorticoids and anticonvulsants
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00417612

United States, Connecticut
Yale University School of Medicine
New Haven, Connecticut, United States, 06520
Sponsors and Collaborators
Yale University
Principal Investigator: Thomas O. Carpenter, MD Yale University
  More Information

Responsible Party: Thomas Carpenter, Professor of Pediatrics, Yale University
ClinicalTrials.gov Identifier: NCT00417612     History of Changes
Other Study ID Numbers: P50 AR054086, P50AR054086, 1P50AR054086-01
Study First Received: December 28, 2006
Last Updated: January 29, 2013
Health Authority: United States: Federal Government

Keywords provided by Yale University:
Rickets, Hypophosphatemia
Rickets, Vitamin D-Resistant
Rickets, X-linked hypophosphatemic

Additional relevant MeSH terms:
Familial Hypophosphatemic Rickets
Rickets, Hypophosphatemic
Hypophosphatemia, Familial
Parathyroid Diseases
Endocrine System Diseases
Bone Diseases, Metabolic
Bone Diseases
Musculoskeletal Diseases
Calcium Metabolism Disorders
Metabolic Diseases
Vitamin D Deficiency
Deficiency Diseases
Nutrition Disorders
Phosphorus Metabolism Disorders
Renal Tubular Transport, Inborn Errors
Kidney Diseases
Urologic Diseases
Metal Metabolism, Inborn Errors
Metabolism, Inborn Errors
Genetic Diseases, Inborn

ClinicalTrials.gov processed this record on September 16, 2014