CKDNCT06712719
Effects of Dietary Phosphorus on Phosphorus and Calcium Whole-Body Balance and Kinetics in Moderate CKD
A study testing LP then HP and HP then LP in people with CKD, run by University of Minnesota at 1 site in United States.
Trial summary
The aim of the study is to look at the effects of dietary phosphorus on phosphorous and calcium whole-body balance and kinetics in moderate chronic kidney disease (CKD). N = 14 enrolled subjects will be randomly assigned to a cross-over order of (A) Low P Diet, High P Diet. Read more about this study
- Who is it for?
- Ages 30 to 75 years
- Conditions the study is for
- CKD
- What is being tested?
- LP then HP and HP then LP
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 14 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Dec 2026to May 2027
- Phase
- Interventional
- 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 30 to 75 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Men or women, ages 30-75 years old, any race or ethnicity
- Moderate CKD, defined by KDIGO as eGFR category 3b (30-44 mL/min) or 4 (16-29 mL/min) with albuminuria categories A1-A3
- Serum intact parathyroid hormone above assay normal limit
- Female subjects must be postmenopausal (>12 months since last menstrual period), surgically sterile, or confirmed not pregnant by pregnancy test
- Must be on stable doses of medications (except those noted in exclusion criteria) for at least 4 weeks prior to the study
- Willing to discontinue supplements (e.g., vitamin D, calcium, multivitamin/minerals, or others) upon enrollment until completion of the study
- Adequate vitamin D status defined as serum 25D > 20 ng/mL based on National Academy of Medicine (then Institute of Medicine) criteria.
Who cannot join
- Plans to initiate dialysis within 6 months
- Hypercalcemia defined as corrected serum calcium >9.8 mg/dL within past 3 months
- Hyperkalemia defined as serum potassium >5.5 mg/dL within past 3 months
- Hyperphosphatemia defined as serum phosphate >5.5 mg/dL within past 3 months
- Intestinal disease that alters absorption or normal intestinal function including celiac disease, small bowel resection, bariatric surgery, or chronic diarrhea/malabsorption
- Serious, uncontrolled underlying systemic disease including diabetes, lupus, hypertension in the opinion of their physician
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- Pregnant or breastfeeding
- Prescribed and taken a phosphate binder medication, calcitriol, vitamin D analogs, calcimimetics, PTH analogues, and other medications that may alter Ca and P metabolism within past 4 weeks
- Non-English speaking
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Study Coordinator contact
United States1 site
Indiana University School of Medicine
Indianapolis, Indiana, 46202
Mary Balmes-Fenwick, 317-948-7772, mbalmes@iu.edu
Sharon M Moe, MD
About this study
The aim of the study is to look at the effects of dietary phosphorus on phosphorous and calcium whole-body balance and kinetics in moderate chronic kidney disease (CKD). N = 14 enrolled subjects will be randomly assigned to a cross-over order of (A) Low P Diet, High P Diet. Each cross-over phase will be 19 days and consist of a 7-day outpatient, controlled diet period, followed by a 5- day inpatient, controlled diet, balance, and kinetic study period, followed by a second 7-day outpatient, controlled diet period.
Read the detailed description
Chronic kidney disease (CKD) affects approximately 37 million (1 in 7) U.S. adults, most of whom experience mineral and bone disorders (CKD-MBD) that increase risk for cardiovascular events, bone fractures, and death. Dietary and pharmaceutical treatments for CKD-MBD have diverse effects on serum calcium and phosphorus levels, but their effects on the underlying physiological processes of calcium and phosphorus balance are largely unknown. This study aims to determine the effects of a low versus high phosphorus bioaccessibility diet on whole-body calcium and phosphorus balance and kinetics, including measures such as estimated intestinal absorption. This study will be a randomized two-phase cross-over design trial that will include a controlled study diet, a phosphorus isotope as a tracer for kinetic modeling, stool and urine collections, and blood draws. After screening, eligible participants who choose to enroll in the study will be asked to participate in two cross-over sessions, each of approximately 3 weeks (19 days) duration during which time all food will be provided according to the randomized diet intervention assignment. After the first week on the study diet, participants will be asked to stay at the clinical research center when they will be given oral and intravenous doses of phosphorus isotope. Serial blood draws and complete urine and fecal collections will be made for 5 days, then the final week will only include blood draws. Between cross-over sessions, there will be a washout period of 1-3 weeks. Participants will then switch diets and repeat the same study process as the first session. Calcium and phosphorus whole-body balance, intestinal absorption, renal excretion, and movement to and from bone will be determined for both minerals. This project will provide foundational knowledge of calcium and phosphorus physiology in CKD that will support progress towards preventing morbidity and mortality associated with CKD-MBD.
- Conditions
- CKD
- Being tested
- LP then HP, HP then LP
- Keywords
- phosphorus, phosphate, balance, diet, calcium
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
LP then HPOther
Cross-over order of LP then HP diet. Each cross-over phase will be 19 days and consist of a 7-day outpatient, controlled diet period, followed by a 5-day inpatient, controlled diet, balance, and kinetic study period, followed by a second 7-day outpatient, controlled diet period.
HP then LPOther
Cross-over order of HP then LP diet. Each cross-over phase will be 19 days and consist of a 7-day outpatient, controlled diet period, followed by a 5-day inpatient, controlled diet, balance, and kinetic study period, followed by a second 7-day outpatient, controlled diet period.
| Study group | Role | What they receive |
|---|---|---|
| CKD patients group 1 | Experimental | assigned to Low P Diet (LP) then High P Diet (HP), Receives: Other: LP then HP |
| CKD patients group 2 | Experimental | assigned to HP, then LP. Receives: Other: HP then LP |
What is being measured
The primary outcome is the main question the study is designed to answer.
Phosphorus Balance
Determined by analysis of phosphorus content in complete 24-hour urine and stool collections, subtracted from the diet phosphorus content consumed
Measured: 5 days
Calcium Balance
Determined by analysis of calcium content in complete 24-hour urine and stool collections, subtracted from the diet calcium content consumed
Measured: 5 days
Secondary outcomes (13)
Fractional phosphorus absorption
Determined by kinetic modeling of serum, urine, and stool P-33 isotope after oral and IV isotope administrations
Measured: 12 days
Bone phosphorus balance
Determined by kinetic modeling of serum, urine, and stool P-33 isotope after oral and IV isotope administrations
Measured: 12 days
Bone calcium balance
Determined from the natural stable isotope ratio of 44-Ca to 42-Ca in serum and urine
Measured: 5 days and 12 days
Urine phosphorus
Determined from the 24-hour urine collections over 1 week (daily average)
Measured: 1 week
Urine calcium
Determined from the 24-hour urine collections over 1 week (daily average)
Measured: 1 week
Net phosphorus absorption
Determined by analysis of phosphorus content in complete stool collections, subtracted from the diet phosphorus content consumed, divided by the diet phosphorus consumed.
Measured: 1 week
Net calcium absorption
Determined by analysis of calcium content in complete stool collections, subtracted from the diet calcium content consumed, divided by the diet phosphorus consumed
Measured: 1 week
Creatinine clearance
Creatinine clearance will be determined from the 2-hour fasting urine and a mid-point blood sample collected on Day 8.
Measured: 2hours, day 8
Serum Fibroblast growth factor-23
Measured in a fasting blood collection on Day 1 and Day 8.
Measured: Day1, Day8
Serum Parathyroid hormone
Measured in a fasting blood collection on Day 1 and Day 8.
Measured: Day1, Day8
Serum 1,25-dihydroxyvitamin D
Measured in a fasting blood collection on Day 1 and Day 8.
Measured: Day1, Day8
Serum phosphate
Measured in a fasting blood collection on Day 1 and Day 8.
Measured: Day1, Day8
Serum calcium
Measured in a fasting blood collection on Day 1 and Day 8.
Measured: Day1, Day8
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Dec 2024
- Study start1 Dec 2026 (estimated)
- Primary completionMay 2027 (estimated)
- Study completionMay 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for CKDStudies of the same condition, open and under way.
- More trials run by University of MinnesotaThe 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
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 14 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Minnesota
- Sponsor type
- University, hospital or other
- Collaborators
- Indiana University
- Responsible party
- Sponsor
- Investigators
- Kathleen Hill Gallant, PhD, Principal investigator, University of Minnesota
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06712719
- Sponsor's protocol ID
- TBD2
- Status last verified
- Nov 2026
- First submitted
- 26 Nov 2024
- Last updated
- 3 Nov 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Dietary Phosphorus on Phosphorus and Calcium Whole-Body Balance and Kinetics in Moderate CKD
- ClinicalTrials.gov ID
- NCT06712719
- Acronym / sponsor ID
- TBD2
- Conditions
- CKD
- Keywords
- phosphorus, phosphate, balance, diet, calcium
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 14 participants (estimated)
- Lead sponsor
- University of MinnesotaUniversity, hospital or other
- Collaborators
- Indiana University
- Study start
- 1 Dec 2026 (estimated)
- Primary completion
- May 2027 (estimated)
- Study completion
- May 2027 (estimated)
- First posted
- 2 Dec 2024 (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.
The aim of the study is to look at the effects of dietary phosphorus on phosphorous and calcium whole-body balance and kinetics in moderate chronic kidney disease (CKD). N = 14 enrolled subjects will be randomly assigned to a cross-over order of (A) Low P Diet, High P Diet. Each cross-over phase will be 19 days and consist of a 7-day outpatient, controlled diet period, followed by a 5- day inpatient, controlled diet, balance, and kinetic study period, followed by a second 7-day outpatient, controlled diet period.
Detailed description
Chronic kidney disease (CKD) affects approximately 37 million (1 in 7) U.S. adults, most of whom experience mineral and bone disorders (CKD-MBD) that increase risk for cardiovascular events, bone fractures, and death. Dietary and pharmaceutical treatments for CKD-MBD have diverse effects on serum calcium and phosphorus levels, but their effects on the underlying physiological processes of calcium and phosphorus balance are largely unknown. This study aims to determine the effects of a low versus high phosphorus bioaccessibility diet on whole-body calcium and phosphorus balance and kinetics, including measures such as estimated intestinal absorption. This study will be a randomized two-phase cross-over design trial that will include a controlled study diet, a phosphorus isotope as a tracer for kinetic modeling, stool and urine collections, and blood draws. After screening, eligible participants who choose to enroll in the study will be asked to participate in two cross-over sessions, each of approximately 3 weeks (19 days) duration during which time all food will be provided according to the randomized diet intervention assignment. After the first week on the study diet, participants will be asked to stay at the clinical research center when they will be given oral and intravenous doses of phosphorus isotope. Serial blood draws and complete urine and fecal collections will be made for 5 days, then the final week will only include blood draws. Between cross-over sessions, there will be a washout period of 1-3 weeks. Participants will then switch diets and repeat the same study process as the first session. Calcium and phosphorus whole-body balance, intestinal absorption, renal excretion, and movement to and from bone will be determined for both minerals. This project will provide foundational knowledge of calcium and phosphorus physiology in CKD that will support progress towards preventing morbidity and mortality associated with CKD-MBD.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| CKD patients group 1 | Experimental | Other: LP then HPassigned to Low P Diet (LP) then High P Diet (HP), |
| CKD patients group 2 | Experimental | Other: HP then LPassigned to HP, then LP. |
Who may qualify
- Ages
- 30 to 75 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Men or women, ages 30-75 years old, any race or ethnicity
- Moderate CKD, defined by KDIGO as eGFR category 3b (30-44 mL/min) or 4 (16-29 mL/min) with albuminuria categories A1-A3
- Serum intact parathyroid hormone above assay normal limit
- Female subjects must be postmenopausal (>12 months since last menstrual period), surgically sterile, or confirmed not pregnant by pregnancy test
- Must be on stable doses of medications (except those noted in exclusion criteria) for at least 4 weeks prior to the study
Key exclusion criteria (9 listed)
- Plans to initiate dialysis within 6 months
- Hypercalcemia defined as corrected serum calcium >9.8 mg/dL within past 3 months
- Hyperkalemia defined as serum potassium >5.5 mg/dL within past 3 months
- Hyperphosphatemia defined as serum phosphate >5.5 mg/dL within past 3 months
- Intestinal disease that alters absorption or normal intestinal function including celiac disease, small bowel resection, bariatric surgery, or chronic diarrhea/malabsorption
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 |
|---|---|---|
| LP then HPCross-over order of LP then HP diet. Each cross-over phase will be 19 days and consist of a 7-day outpatient, controlled diet period, followed by a 5-day inpatient, controlled diet, balance, and kinetic study period, followed by a second 7-day outpatient, controlled diet period. | Other | CKD patients group 1 |
| HP then LPCross-over order of HP then LP diet. Each cross-over phase will be 19 days and consist of a 7-day outpatient, controlled diet period, followed by a 5-day inpatient, controlled diet, balance, and kinetic study period, followed by a second 7-day outpatient, controlled diet period. | Other | CKD patients group 2 |
Primary outcome
Phosphorus Balance
Time frame: 5 days
Determined by analysis of phosphorus content in complete 24-hour urine and stool collections, subtracted from the diet phosphorus content consumed
Calcium Balance
Time frame: 5 days
Determined by analysis of calcium content in complete 24-hour urine and stool collections, subtracted from the diet calcium content consumed
13 secondary outcomes
Fractional phosphorus absorption
Time frame: 12 days
Bone phosphorus balance
Time frame: 12 days
Bone calcium balance
Time frame: 5 days and 12 days
Urine phosphorus
Time frame: 1 week
Urine calcium
Time frame: 1 week
Net phosphorus absorption
Time frame: 1 week
Net calcium absorption
Time frame: 1 week
Creatinine clearance
Time frame: 2hours, day 8
Serum Fibroblast growth factor-23
Time frame: Day1, Day8
Serum Parathyroid hormone
Time frame: Day1, Day8
Serum 1,25-dihydroxyvitamin D
Time frame: Day1, Day8
Serum phosphate
Time frame: Day1, Day8
Serum calcium
Time frame: Day1, Day8
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 3 Nov 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.
Study Coordinator contact
Kathleen Hill Gallant, PhD principal investigator
University of Minnesota
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing LP then HP and HP then LP in people with CKD, run by University of Minnesota 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 7 inclusion and 9 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: opening soon, as of the sponsor's last update on 3 Nov 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.
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 Kathleen Hill Gallant, PhD (612-625-5285, hillkm@umn.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Phosphorus Balance (time frame: 5 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 3 Nov 2026.