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

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ClinicalTrials.gov Identifier: NCT00417612
Recruitment Status : Completed
First Posted : January 1, 2007
Results First Posted : October 28, 2014
Last Update Posted : March 17, 2020
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Information provided by (Responsible Party):
Thomas Carpenter, Yale University

Brief Summary:
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 or disease Intervention/treatment Phase
Hypophosphatemia, Familial Hyperparathyroidism Drug: Paricalcitol Other: Placebo Phase 3

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.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 33 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, 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)
Study Start Date : January 2007
Actual Primary Completion Date : August 2012
Actual Study Completion Date : August 2012

Arm Intervention/treatment
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

Primary Outcome Measures :
  1. Area Under the Curve for Parathyroid Hormone (PTHauc) Measurement [ Time Frame: Measured at baseline and Month 12 ]
    Mean area under the curve for parathyroid hormone levels (PTHauc) sampled during a 26 hour study period, for Paricalcitol (Active Drug) and Placebo groups at Baseline and Month 12 .

  2. Area Under the Curve for Parathyroid Hormone (PTH; Percentage Decrease) [ Time Frame: Measured at baseline and Month 12 ]
    Mean PTHauc (% decrease) for Paricalcitol (Active Drug) and Placebo from Baseline to Month 12.

  3. Reduction of Parathyroid Hormone Area Under the Curve (PTHauc) of 20% or Greater [ Time Frame: Measured at baseline and Month 12 ]
    Clinically significant reduction of Mean PTHauc (% decrease >/= 20) for Paricalcitol (Active Drug) and Placebo from Baseline to Month 12.

Secondary Outcome Measures :
  1. Static Parameters of Serum Alkaline Phosphatase at Baseline and 1 Year for Paricalcitol and Placebo Arms. [ Time Frame: Measured at baseline and Month 12 ]
  2. Serum Calcium [ Time Frame: Measured at baseline and Month 12 ]
  3. Bone Scan Severity Score [ Time Frame: Measured at baseline and Month 12 ]

    99-Tc-methylenediphosphonate bone scans were completed and analyzed using the following scale*: Bone scan severity scale with minimum score of 0 and maximum score of 4 (0 is no disease and 4 is greatest severity of disease).

    Appearance of lumbar spine and the sacroiliac region were used as internal references to which all suspected lesions were compared, and scored as follows:

    grade 0, normal scan without suspicious lesions grade 1, lesion(s) less intense than normal lumbar spine grade 2, lesion(s) similar in intensity to normal lumbar spine grade 3, lesions more intense than normal lumbar spine but similar to the normal sacroiliac region grade 4, lesions more intense than the normal sacroiliac region.

    *devised by nuclear medicine radiologist at Yale New Haven Hospital

  4. Percent Change in Urinary Calcium Excretion From Baseline to 1 Year [ Time Frame: Measured at baseline and Month 12 ]
    Percent change in daily urinary calcium excretion, which is calculated the measurements of the calcium in the subject's 24-hr urine collections done at baseline and at the 1 year timepoints

  5. Serum Intact Fibroblast Growth Factor 23 (FGF23) [ Time Frame: Measured at baseline and Month 12 ]
  6. Serum 1,25 (OH)2D [ Time Frame: Measured at baseline and Month 12 ]

Information from the National Library of Medicine

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Ages Eligible for Study:   9 Years and older   (Child, Adult, Older Adult)
Sexes Eligible for Study:   All
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-hydroxy 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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00417612

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United States, Connecticut
Yale University School of Medicine
New Haven, Connecticut, United States, 06520
Sponsors and Collaborators
Yale University
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
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Principal Investigator: Thomas O. Carpenter, MD Yale University
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
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Responsible Party: Thomas Carpenter, Professor of Pediatrics, Yale University
ClinicalTrials.gov Identifier: NCT00417612    
Other Study ID Numbers: 0607001636
P50AR054086 ( U.S. NIH Grant/Contract )
1P50AR054086-01 ( U.S. NIH Grant/Contract )
First Posted: January 1, 2007    Key Record Dates
Results First Posted: October 28, 2014
Last Update Posted: March 17, 2020
Last Verified: March 2020
Keywords provided by Thomas Carpenter, Yale University:
Rickets, Hypophosphatemia
Rickets, Vitamin D-Resistant
Rickets, X-linked hypophosphatemic
Additional relevant MeSH terms:
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Rickets, Hypophosphatemic
Familial Hypophosphatemic Rickets
Hypophosphatemia, Familial
Parathyroid Diseases
Endocrine System Diseases
Phosphorus Metabolism Disorders
Metabolic Diseases
Bone Diseases, Metabolic
Bone Diseases
Musculoskeletal Diseases
Calcium Metabolism Disorders
Vitamin D Deficiency
Deficiency Diseases
Nutrition Disorders
Renal Tubular Transport, Inborn Errors
Kidney Diseases
Urologic Diseases
Metal Metabolism, Inborn Errors
Metabolism, Inborn Errors
Genetic Diseases, Inborn