Chronic Kidney Disease (Stage 3-4)PACKNCT07368946
Phosphate Assessment in Chronic Kidney Disease Patients Study
A study testing Dietary Phosphorus Intake in people with Chronic Kidney Disease (Stage 3-4) and Chronic Kidney Disease Mineral and Bone Disorder, run by University of Texas Southwestern Medical Center at 1 site in United States.
Trial summary
The proposed pilot feeding study aims to explore novel pathways in phosphate metabolism and identify new biomarkers, as well as to develop a compound index for assessing phosphate overload with high validity and reliability. Investigators will address the following specific aims: 1). Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Chronic Kidney Disease (Stage 3-4), Chronic Kidney Disease Mineral and Bone Disorder
- What is being tested?
- Dietary Phosphorus Intake
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteUnited States
- Study dates
- 9 May 2025to 31 Dec 2026
- 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 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Men or women aged 18 years or older, of any race/ethnicity
- Women must either be post-menopausal or have no monthly menstrual cycle
- Estimated total daily energy expenditure (TDEE) of 1700 - 2700 calories
- eGFR >15 ml/min/1.73m2 - < 60 ml/min/1.73m2 for the CKD group (CKD Stage 3 or Stage 4)
- eGFR ≥ 60 ml/min/1.73m2 and negative urine protein on dipstick test for the non-CKD group
- English speaking
Who cannot join
- Pregnant, currently breastfeeding, or <3 months postpartum
- Current dialysis or kidney transplant patient
- Current use of insulin or chemotherapy drugs
- Smokes cigarettes or uses e-cigarettes (vapes)
- Uses nicotine products or other recreational drugs
- Medical history of stroke or myocardial infarction (MI)
Show all 30Show fewer
- Medical history of conditions that can affect phosphate metabolism (i.e., uncontrolled thyroid disorder, parathyroid disorder, or gastrointestinal malabsorption disorders [Crohn's, ulcerative colitis, and celiac disease], cirrhosis)
- Current use of certain medications that directly alter phosphate levels (i.e., phosphate binders; phosphate supplements, irregular use of iron)
- Regular use of laxatives
- Hypo- or hyperphosphatemia (serum phosphate < 2.5 or > 4.6 mg/dl)
- Hypo- or hypercalcemia (serum calcium < 8.4 or > 10.7 mg/dl)
- Severe anemia (hemoglobin < 8 g/dl for women and < 9 g/dl for men)
- Severe hyperglycemia (serum blood glucose > 300 mg/dl)
- Body weight less than <110 lbs (due to risk for phlebotomy-induced anemia)
- Received a blood transfusion in the last four months
- Extreme hypertension as demonstrated by a blood pressure > 180/120 as the average of 3 blood pressures taken during the screening/baseline, or extremely low blood pressure < 80/50
- Unwilling or unable to eat study meals
- Lack of access to a functional refrigerator or freezer
- Lack of access to a microwave or conventional oven
- On low potassium diet
- On low phosphate diet
- Specific dietary restrictions (i.e. vegetarian, vegan, ketogenic, etc.)
- Food allergies including but not limited to milk, egg, soy, nuts, shellfish, and wheat or gluten
- Allergic to sodium phosphate
- Unable or unwilling to complete urinary sample collection or food diaries
- Unable or unwilling to provide informed consent
- Unable to read or speak English
- Participant in other conflict clinical trial
- Unable to complete the study measurements
- Unsafe to participate in this study per investigator's judgement
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
University of Texas Southwestern Medical Center
Dallas, Texas, 75390
Alexandra Hartman, 2146458294, pack.utsw@utsouthwestern.edu
Paola Lanza, MD, 469-852-9550, paola.lanza@utsouthwestern.edu
About this study
Official title: A Pilot Feeding Study to Assess Phosphate Overload in Patients With Chronic Kidney Disease
The proposed pilot feeding study aims to explore novel pathways in phosphate metabolism and identify new biomarkers, as well as to develop a compound index for assessing phosphate overload with high validity and reliability.
Investigators will address the following specific aims: 1). To explore novel pathways of phosphate metabolism and assess the influence of CKD status on these metabolic pathways. 2). To identify novel biomarkers for phosphate overload that reflect changes in dietary phosphorus intake. 3). To develop a compound phosphate overload index that measures dietary phosphorus intake with high validity and reliability.
This study will provide novel insights into phosphate metabolism and the assessment of phosphate overload in CKD patients. This investigation aims to provide preliminary data to further studies for the development of reliable biomarkers in CKD patients, which could contribute significantly to early interventions and improve health outcomes.
Read the detailed description
Specifically, study team propose recruiting 30 participants with CKD and 30 without CKD to investigate the responses of blood metabolites and known biomarkers to a 21-day diet intervention. The intervention will consist of a dietary phosphorus intake of about 777 mg/day for 7 days, followed by an increase to about 1,277mg/day for another 7 days, and a further increase to about 1,777 mg/day for the subsequent 7 days. 1200 mg/day and 1700 mg/day phosphorus diets will be achieved by providing participants with sodium phosphate capsules and 777 mg/day meals. The meal plan will maintain consistent intake of calories, sodium, potassium, and calcium throughout the 21-day intervention. Sodium, calcium, and potassium content will not change significantly throughout the intervention. The overnight fasting blood and 24-hour and random urine samples will be collected at the baseline and end of each phase.
- Being tested
- Dietary Phosphorus Intake
- Keywords
- chronic kidney disease, study diet, feeding study, pilot, oral phosphate feeding
- Medical subject headings
- Renal Insufficiency, Chronic, Chronic Kidney Disease-Mineral and Bone Disorder
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dietary Phosphorus IntakeDietary supplement
Dietary phosphorus intake of about 777 mg/day for 7 days, followed by an increase to about 1,277mg/day for another 7 days, and a further increase to about 1,777 mg/day for the subsequent 7 days.
The meal plan will maintain consistent intake of calories, sodium, potassium, and calcium throughout the 21-day intervention.
1200 mg/day and 1700 mg/day phosphorus diets will be achieved by providing participants with sodium phosphate capsules and 777 mg/day meals.
| Study group | Role | What they receive |
|---|---|---|
| Chronic Kidney Disease Patients | Active comparator | Participants with eGFR >15 ml/min/1.73m2 - < 60 ml/min/1.73m2 for the CKD group Receives: Dietary Supplement: Dietary Phosphorus Intake |
| Control Group | Active comparator | Healthy participants without CKD eGFR ≥ 60 ml/min/1.73m2 Receives: Dietary Supplement: Dietary Phosphorus Intake |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in serum phosphate levels
Circulating serum phosphate levels (mg/dL) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Change in parathyroid hormone (PTH) levels
Circulating PTH levels (pg/mL) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Change in C-terminal Fibroblast Growth Factor 23 (FGF23) levels
Circulating C-terminal FGF23 levels (RU/mL) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Change in Fibroblast Growth Factor 23 (FGF23) levels
Circulating FGF23 levels (pg/mL) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Phosphate burden indices
Phosphate burden indices, developed using machine learning methods to systematically incorporate both known biomarkers and novel biomarkers. No units have been identified, we anticipate creating a score.
Measured: Baseline, week 1, week 2, week 3
Secondary outcomes (6)
Change in serum calcium levels
Circulating serum calcium levels (mg/dL) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Change in Alkaline Phosphatase (ALP) levels
Circulating serum ALP levels (U/L) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Change in 1,25-dihydroxyvitamin D levels
Circulating serum 1,25-dihydroxyvitamin D levels (pg/mL) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Change in Bone-Specific Alkaline Phosphatase (BALP) levels
Circulating serum BALP levels (U/L) will be measured using standard clinical laboratory assays
Measured: Baseline, week 1, week 2, and week 3
Change in urinary calcium levels
Circulating urinary calcium excretion levels (mg/day) will be measured using standardized laboratory urine assays
Measured: Baseline, week 1, week 2, and week 3
Change in urinary phosphorus levels
Circulating urinary phosphorus excretion levels (mg/day) will be measured using standardized laboratory urine assays
Measured: Baseline, week 1, week 2, and week 3
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Jan 2026
- Study start9 May 2025
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Chronic Kidney Disease (Stage 3-4)Studies of the same condition, open and under way.
- More trials run by University of Texas Southwestern Medical CenterThe 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
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Texas Southwestern Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Jing Chen, University of Texas Southwestern Medical Center
- Investigators
- Jing Chen, MD, Principal investigator, University of Texas Southwestern Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07368946
- Sponsor's protocol ID
- STU-2024-1240
- Other IDs
- 68418
- Acronym
- PACK
- Status last verified
- Jan 2026
- First submitted
- 17 Nov 2025
- Last updated
- 28 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: IRB approval is required before sharing IPD.
Study at a glance
From the registry record, last updated by the sponsor on 28 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Pilot Feeding Study to Assess Phosphate Overload in Patients With Chronic Kidney Disease
- ClinicalTrials.gov ID
- NCT07368946
- Acronym / sponsor ID
- PACK / STU-2024-1240
- Keywords
- chronic kidney disease, study diet, feeding study, pilot, oral phosphate feeding
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- University of Texas Southwestern Medical CenterUniversity, hospital or other
- Study start
- 9 May 2025 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 27 Jan 2026 (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 proposed pilot feeding study aims to explore novel pathways in phosphate metabolism and identify new biomarkers, as well as to develop a compound index for assessing phosphate overload with high validity and reliability.
Investigators will address the following specific aims: 1). To explore novel pathways of phosphate metabolism and assess the influence of CKD status on these metabolic pathways. 2). To identify novel biomarkers for phosphate overload that reflect changes in dietary phosphorus intake. 3). To develop a compound phosphate overload index that measures dietary phosphorus intake with high validity and reliability.
This study will provide novel insights into phosphate metabolism and the assessment of phosphate overload in CKD patients. This investigation aims to provide preliminary data to further studies for the development of reliable biomarkers in CKD patients, which could contribute significantly to early interventions and improve health outcomes.
Detailed description
Specifically, study team propose recruiting 30 participants with CKD and 30 without CKD to investigate the responses of blood metabolites and known biomarkers to a 21-day diet intervention. The intervention will consist of a dietary phosphorus intake of about 777 mg/day for 7 days, followed by an increase to about 1,277mg/day for another 7 days, and a further increase to about 1,777 mg/day for the subsequent 7 days. 1200 mg/day and 1700 mg/day phosphorus diets will be achieved by providing participants with sodium phosphate capsules and 777 mg/day meals. The meal plan will maintain consistent intake of calories, sodium, potassium, and calcium throughout the 21-day intervention. Sodium, calcium, and potassium content will not change significantly throughout the intervention. The overnight fasting blood and 24-hour and random urine samples will be collected at the baseline and end of each phase.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Chronic Kidney Disease Patients | Active comparator | Dietary Supplement: Dietary Phosphorus IntakeParticipants with eGFR >15 ml/min/1.73m2 - < 60 ml/min/1.73m2 for the CKD group |
| Control Group | Active comparator | Dietary Supplement: Dietary Phosphorus IntakeHealthy participants without CKD eGFR ≥ 60 ml/min/1.73m2 |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Men or women aged 18 years or older, of any race/ethnicity
- Women must either be post-menopausal or have no monthly menstrual cycle
- Estimated total daily energy expenditure (TDEE) of 1700 - 2700 calories
- eGFR >15 ml/min/1.73m2 - < 60 ml/min/1.73m2 for the CKD group (CKD Stage 3 or Stage 4)
- eGFR ≥ 60 ml/min/1.73m2 and negative urine protein on dipstick test for the non-CKD group
Key exclusion criteria (30 listed)
- Pregnant, currently breastfeeding, or <3 months postpartum
- Current dialysis or kidney transplant patient
- Current use of insulin or chemotherapy drugs
- Smokes cigarettes or uses e-cigarettes (vapes)
- Uses nicotine products or other recreational drugs
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 |
|---|---|---|
| Dietary Phosphorus IntakeDietary phosphorus intake of about 777 mg/day for 7 days, followed by an increase to about 1,277mg/day for another 7 days, and a further increase to about 1,777 mg/day for the subsequent 7 days. The meal plan will maintain consistent intake of calories, sodium, potassium, and calcium throughout the 21-day intervention. 1200 mg/day and 1700 mg/day phosphorus diets will be achieved by providing participants with sodium phosphate capsules and 777 mg/day meals. | Dietary supplement | Chronic Kidney Disease Patients, Control Group |
Primary outcome
Change in serum phosphate levels
Time frame: Baseline, week 1, week 2, and week 3
Circulating serum phosphate levels (mg/dL) will be measured using standard clinical laboratory assays
Change in parathyroid hormone (PTH) levels
Time frame: Baseline, week 1, week 2, and week 3
Circulating PTH levels (pg/mL) will be measured using standard clinical laboratory assays
Change in C-terminal Fibroblast Growth Factor 23 (FGF23) levels
Time frame: Baseline, week 1, week 2, and week 3
Circulating C-terminal FGF23 levels (RU/mL) will be measured using standard clinical laboratory assays
Change in Fibroblast Growth Factor 23 (FGF23) levels
Time frame: Baseline, week 1, week 2, and week 3
Circulating FGF23 levels (pg/mL) will be measured using standard clinical laboratory assays
Phosphate burden indices
Time frame: Baseline, week 1, week 2, week 3
Phosphate burden indices, developed using machine learning methods to systematically incorporate both known biomarkers and novel biomarkers. No units have been identified, we anticipate creating a score.
6 secondary outcomes
Change in serum calcium levels
Time frame: Baseline, week 1, week 2, and week 3
Change in Alkaline Phosphatase (ALP) levels
Time frame: Baseline, week 1, week 2, and week 3
Change in 1,25-dihydroxyvitamin D levels
Time frame: Baseline, week 1, week 2, and week 3
Change in Bone-Specific Alkaline Phosphatase (BALP) levels
Time frame: Baseline, week 1, week 2, and week 3
Change in urinary calcium levels
Time frame: Baseline, week 1, week 2, and week 3
Change in urinary phosphorus levels
Time frame: Baseline, week 1, week 2, and week 3
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 28 Jan 2026.
- Individual participant dataSharing planned: Yes. IRB approval is required before sharing IPD.
Related trials for Chronic Kidney Disease (Stage 3-4)
Enrolling by invitationEarly Phase 1
Truway Diagnostic Tools in Primary Care
Chronic Disease, Type 2 Diabetes Mellitus (T2DM), Obesity, Overweight
Recruiting
Effect of Synbiotic Therapy on Renal Function Outcomes in Patients With Chronic Kidney Disease Stage III-IV: A Double-blind Randomized Placebo-controlled Trial.
Chronic Kidney Disease (Stage 3-4)
Enrolling by invitationObservational study
AK+ Guard™ Pilot Study in Chronic Kidney Disease: Outpatient Diagnostic Accuracy and Remote Monitoring
Hyperkalemia, Chronic Kidney Disease (Stage 3-4)
RecruitingPhase 3
A Phase III Study to Evaluate the Effect of Balcinrenone/Dapagliflozin in Patients With CKD Stage 3b and 4 (BalanceD-CKD)
Renal Insufficiency, Chronic
Active, not recruitingObservational study
Metabolic Status and Risk of Chronic Kidney Disease in French Overseas Populations With Morbid Obesity (OBECAMcohort).
Morbid Obesity, Chronic Kidney Disease (Stage 3-4)
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.
Jing Chen, MD principal investigator
University of Texas Southwestern Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Dietary Phosphorus Intake in people with Chronic Kidney Disease (Stage 3-4) and Chronic Kidney Disease Mineral and Bone Disorder, run by University of Texas Southwestern Medical Center 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 6 inclusion and 30 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 28 Jan 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 Alexandra Hartman (214-645-8294, pack.utsw@utsouthwestern.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in serum phosphate levels (time frame: Baseline, week 1, week 2, and week 3). The study lists 5 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 28 Jan 2026.