HypophosphatemiaEarly Phase 1NCT03771105
The Impact of Phosphate Metabolism on Healthy Aging
A Early Phase 1 study testing phosphate in people with Hypophosphatemia and Rickets, run by Yale University at 1 site in United States.
Trial summary
Determine the association between duration and dose of chronic conventional therapy with Pi and renal (nephrocalcinosis/nephrolithiasis), vascular (endothelial function), and cardiovascular function (echo- cardiography) in patients with hereditary hypophosphatemic rickets with hypercalciuria (HHRH) and patients with… Read more about this study
- Who is it for?
- Ages 13 years and older
- Conditions the study is for
- Hypophosphatemia, Rickets, Hypercalciuria
- What is being tested?
- phosphate
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jan 2019to Apr 2028
- Phase
- Early Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 13 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Children above the age of 13 years
- Younger and older adults with XLH and HHRH with confirmed NPT2c mutations affecting both copies of the NPT2c gene (HHRH) or one copy of the PHEX gene (XLH)
- Be willing to provide access to prior medical records to determine eligibility including imaging, biochemical, medical, and surgical history data
- Be willing and able to complete all aspects of the study
- Be willing to adhere to the study visit schedule and comply with the assessments (in the opinion of the investigator).
Who cannot join
- Subjects will be excluded, if they are children younger than age 13 years
- Subjects that have other diseases likely to impact bone and mineral metabolism (e.g. renal, hepatic, gastrointestinal disorders, and malignancy),
- Subjects that are currently pregnant,
- Subjects that received medical therapy or developed any condition, which in the opinion of the investigator, could present a concern for either subject safety or difficulty with data interpretation.
- Subjects will be excluded from Aim 2, if they are unable to tolerate supplemental phosphate.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Yale University School of Medicine
New Haven, Connecticut, 06511
Clemens Bergwitz, M.D., 203-737-5450, clemens.bergwitz@yale.edu
About this study
Determine the association between duration and dose of chronic conventional therapy with Pi and renal (nephrocalcinosis/nephrolithiasis), vascular (endothelial function), and cardiovascular function (echo- cardiography) in patients with hereditary hypophosphatemic rickets with hypercalciuria (HHRH) and patients with X-linked hypophosphatemia (XLH).
Read the detailed description
The central hypothesis of this proposal is that patients with X-linked hypophosphatemia (XLH), when matched for duration and dose of phosphate (Pi) therapy to patients with hereditary hypophosphatemic rickets with hypercalciuria (HHRH), will evidence greater cardiovascular and vascular debility than patients with HHRH. The overall objectives of this project are to utilize our existing longitudinal databases for individuals with XLH and HHRH through an interdisciplinary collaboration between pediatric and adult endocrinology to: i) quantify the impact of exposure to Pi therapy across the lifespan on cardiovascular and renal complications, which are key aging endpoints, ii) determine the acute response to Pi loading in XLH and HHRH by studying the changes in surrogate markers of cardiovascular and renal function.
- Conditions
- Hypophosphatemia, Rickets, Hypercalciuria, XLH, HHRH
- Being tested
- phosphate
- Medical subject headings
- Hypophosphatemia, Rickets, Hypercalciuria
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
phosphateDrug
The target daily phosphate (Pi) intake is 3,500 mg/day (dietary intake plus our supplementation) for this study. Subjects will take a supplement of Pi (as KPhos Neutral 250 mg/tablet) to reach this target. Subjects will receive treatment for 30 days.
| Study group | Role | What they receive |
|---|---|---|
| Patients with hereditary hypophosphatemic rickets with HHRH | Experimental | Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) Receives: Drug: phosphate |
| Patients with X-linked Hypophosphatemia | Active comparator | Patients with X-linked hypophosphatemia Receives: Drug: phosphate |
| 15 Patients with X-linked Hypophosphatemia | Active comparator | 15 Patients with X-linked Hypophosphatemia that will receive phosphate treatment for 30 days. Receives: Drug: phosphate |
| 15 Patients Hereditary hypophosphatemic rickets with HHRH | Active comparator | 15 patients withHereditary hypophosphatemic rickets with hypercalciuria (HHRH) that will receive phosphate treatment for 30 days. Receives: Drug: phosphate |
What is being measured
The primary outcome is the main question the study is designed to answer.
Parathyroid Hormone (PTH) levels
PTH levels are expected to increase over baseline after phosphate supplement (Pi).
Measured: 30 days
Fibroblast Growth Factor 23 (FGF23) levels
FGF23 levels are expected to increase over baseline after phosphate supplement (Pi).
Measured: 30 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Dec 2018
- Study start1 Jan 2019
- Primary completionApr 2028 (estimated)
- Study completionApr 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HypophosphatemiaStudies of the same condition, open and under way.
- More trials run by Yale UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Yale University
- Sponsor type
- University, hospital or other
- Collaborators
- National Center for Advancing Translational Sciences (NCATS)
- Responsible party
- Sponsor
- Investigators
- Clemens Bergwitz, MD, Principal investigator, Yale University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03771105
- Sponsor's protocol ID
- 2000023461
- Other IDs
- 1UL1TR001863-01
- Status last verified
- May 2026
- First submitted
- 7 Dec 2018
- Last updated
- 27 May 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 27 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Impact of Phosphate Metabolism on Healthy Aging
- ClinicalTrials.gov ID
- NCT03771105
- Acronym / sponsor ID
- 2000023461
- Conditions
- Hypophosphatemia, Rickets, Hypercalciuria, XLH, HHRH
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Yale UniversityUniversity, hospital or other
- Collaborators
- National Center for Advancing Translational Sciences (NCATS)
- Study start
- 1 Jan 2019 (actual)
- Primary completion
- Apr 2028 (estimated)
- Study completion
- Apr 2028 (estimated)
- First posted
- 10 Dec 2018 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Determine the association between duration and dose of chronic conventional therapy with Pi and renal (nephrocalcinosis/nephrolithiasis), vascular (endothelial function), and cardiovascular function (echo- cardiography) in patients with hereditary hypophosphatemic rickets with hypercalciuria (HHRH) and patients with X-linked hypophosphatemia (XLH).
Detailed description
The central hypothesis of this proposal is that patients with X-linked hypophosphatemia (XLH), when matched for duration and dose of phosphate (Pi) therapy to patients with hereditary hypophosphatemic rickets with hypercalciuria (HHRH), will evidence greater cardiovascular and vascular debility than patients with HHRH. The overall objectives of this project are to utilize our existing longitudinal databases for individuals with XLH and HHRH through an interdisciplinary collaboration between pediatric and adult endocrinology to: i) quantify the impact of exposure to Pi therapy across the lifespan on cardiovascular and renal complications, which are key aging endpoints, ii) determine the acute response to Pi loading in XLH and HHRH by studying the changes in surrogate markers of cardiovascular and renal function.
Study design
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Patients with hereditary hypophosphatemic rickets with HHRH | Experimental | Drug: phosphateHereditary hypophosphatemic rickets with hypercalciuria (HHRH) |
| Patients with X-linked Hypophosphatemia | Active comparator | Drug: phosphatePatients with X-linked hypophosphatemia |
| 15 Patients with X-linked Hypophosphatemia | Active comparator | Drug: phosphate15 Patients with X-linked Hypophosphatemia that will receive phosphate treatment for 30 days. |
| 15 Patients Hereditary hypophosphatemic rickets with HHRH | Active comparator | Drug: phosphate15 patients withHereditary hypophosphatemic rickets with hypercalciuria (HHRH) that will receive phosphate treatment for 30 days. |
Who may qualify
- Ages
- 13 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (5 listed)
- Children above the age of 13 years
- Younger and older adults with XLH and HHRH with confirmed NPT2c mutations affecting both copies of the NPT2c gene (HHRH) or one copy of the PHEX gene (XLH)
- Be willing to provide access to prior medical records to determine eligibility including imaging, biochemical, medical, and surgical history data
- Be willing and able to complete all aspects of the study
- Be willing to adhere to the study visit schedule and comply with the assessments (in the opinion of the investigator).
Key exclusion criteria (5 listed)
- Subjects will be excluded, if they are children younger than age 13 years
- Subjects that have other diseases likely to impact bone and mineral metabolism (e.g. renal, hepatic, gastrointestinal disorders, and malignancy),
- Subjects that are currently pregnant,
- Subjects that received medical therapy or developed any condition, which in the opinion of the investigator, could present a concern for either subject safety or difficulty with data interpretation.
- Subjects will be excluded from Aim 2, if they are unable to tolerate supplemental phosphate.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| phosphateThe target daily phosphate (Pi) intake is 3,500 mg/day (dietary intake plus our supplementation) for this study. Subjects will take a supplement of Pi (as KPhos Neutral 250 mg/tablet) to reach this target. Subjects will receive treatment for 30 days. | Drug | 15 Patients Hereditary hypophosphatemic rickets with HHRH, 15 Patients with X-linked Hypophosphatemia, Patients with X-linked Hypophosphatemia, Patients with hereditary hypophosphatemic rickets with HHRH |
Primary outcome
Parathyroid Hormone (PTH) levels
Time frame: 30 days
PTH levels are expected to increase over baseline after phosphate supplement (Pi).
Fibroblast Growth Factor 23 (FGF23) levels
Time frame: 30 days
FGF23 levels are expected to increase over baseline after phosphate supplement (Pi).
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 May 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Clemens Bergwitz, MD principal investigator
Yale University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing phosphate in people with Hypophosphatemia and Rickets, run by Yale University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 27 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Clemens Bergwitz, MD (203-737-5450, clemens.bergwitz@yale.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Parathyroid Hormone (PTH) levels (time frame: 30 days). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 27 May 2026.