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RecruitingNCT03771105Updated May 27, 2026

The Impact of Phosphate Metabolism on Healthy Aging

An Early Phase 1 interventional study of phosphate in Hypophosphatemia, Rickets and Hypercalciuria, sponsored by Yale University. Recruiting at 1 site in United States. Open to participants aged 13 Years and older. Per ClinicalTrials.gov, last updated 2026-05-27.

Sponsored by Yale University · Early Phase 1, Interventional, and Treatment

From the registry’s dates

  • Started Jan 2019; still recruiting 7 years 10 months later.
Phase
Early Phase 1
Study type
Interventional
Enrollment
30
Allocation
Non-randomized
Ages
13 Years and older
Sex
All
01

Study 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 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.

02

Conditions studied

  • Hypophosphatemia
  • Rickets
  • Hypercalciuria
  • XLH
  • HHRH
03

In context

Hypophosphatemia

53 studies on the registry are indexed under Hypophosphatemia; 16 are open to participants now.

This study's planned enrollment of 30 is below the median of 46 across 26 interventional studies indexed under Hypophosphatemia.

Browse Hypophosphatemia studies →

Lead sponsor

Yale University is the lead sponsor of 1,770 studies on the registry; 294 are open to participants now.

Of its 221 completed or terminated interventional studies of FDA-regulated products, 129 (58%) have results posted.

Browse Yale University studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
13 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • 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).

Exclusion criteria

Exclusion Criteria:

  • 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 ),
  • 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.
Terms in these criteria, in plain language(1)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Cancer (malignancy)

Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.

Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.

05

Study design

Phase
Early Phase 1
Primary purpose
Treatment
Allocation
Non-randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
30 participants (estimated)

Study arms

  • Experimental
    Patients with hereditary hypophosphatemic rickets with HHRH

    Hereditary hypophosphatemic rickets with hypercalciuria (HHRH)

    Drug: phosphate

  • Active comparator
    Patients with X-linked Hypophosphatemia

    Patients with X-linked hypophosphatemia

    Drug: phosphate

  • Active comparator
    15 Patients with X-linked Hypophosphatemia

    15 Patients with X-linked Hypophosphatemia that will receive phosphate treatment for 30 days.

    Drug: phosphate

  • Active comparator
    15 Patients Hereditary hypophosphatemic rickets with HHRH

    15 patients withHereditary hypophosphatemic rickets with hypercalciuria (HHRH) that will receive phosphate treatment for 30 days.

    Drug: phosphate

Interventions

  • Drugphosphate

    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.

06

What researchers measure

Primary outcomes

  1. Parathyroid Hormone (PTH) levels

    PTH levels are expected to increase over baseline after phosphate supplement (Pi).

    Time frame: 30 days

  2. Fibroblast Growth Factor 23 (FGF23) levels

    FGF23 levels are expected to increase over baseline after phosphate supplement (Pi).

    Time frame: 30 days

07

Study locations

1 of 1 sites recruiting
08

References and documents

Study documents

PDFs hosted by the registry, ClinicalTrials.gov.

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Started Jan 2019 (actual). Primary completion is estimated for Apr 2028, 111 months after the start.

How these figures are worked out, and which studies are left out of them.

Registered
Dec 7, 2018
First posted
Dec 10, 2018
StartActual
Jan 1, 2019
Primary completionEst.
Apr 2028
CompletionEst.
Apr 2028
Last update
May 27, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on May 27, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT03771105
Lead sponsor
Yale University
Collaborators
National Center for Advancing Translational Sciences (NCATS)
Responsible party
Sponsor
First posted
Dec 10, 2018
Start date
Jan 1, 2019
Primary completion
Apr 2028 (estimated)
Completion
Apr 2028 (estimated)
Last update
May 27, 2026

Study contacts

Clemens Bergwitz, MD
Contact
clemens.bergwitz@yale.edu
203-737-5450
Clemens Bergwitz, MD
principal investigator · Yale University

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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