Phosphate assessment in people with chronic kidney disease
Official title: A Pilot Feeding Study to Assess Phosphate Overload in Patients With Chronic Kidney Disease
Run by University of Texas Southwestern Medical Center · NCT07368946 · Data updated 2026-11-12
This study will test how increasing dietary phosphate over three weeks affects blood and urine markers in adults with and without stage 3–4 chronic kidney disease.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 60 (estimated) |
| Sponsor | University of Texas Southwestern Medical Center Academic / other |
| Drugs / interventions | chemotherapy |
| Locations | 1 site (Dallas, Texas) |
| Status | Recruiting |
| Started | May 9, 2025 |
| Main results expected | December 31, 2026 |
| Study ends | December 31, 2026 |
| Registry record updated | January 28, 2026 |
| Trial ID | NCT07368946 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates are English-speaking adults with TDEE 1700–2700 kcal/day, including a CKD group with eGFR 15–59 ml/min/1.73m2 (stage 3–4) and a non-CKD group with eGFR ≥60 ml/min/1.73m2 and negative urine protein.
✕Probably not a fit
People on dialysis or with a kidney transplant, pregnant or breastfeeding individuals, current smokers or e-cigarette users, those using insulin or chemotherapy, or those with conditions that affect phosphate metabolism are unlikely to benefit from this protocol.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This pilot feeding study will enroll 30 adults with CKD stage 3–4 and 30 adults without CKD and expose them to a controlled 21-day dietary phosphate intervention. Participants will consume meals providing about 777 mg/day of phosphorus for 7 days, then ~1,277 mg/day for 7 days, and ~1,777 mg/day for the final 7 days, with sodium phosphate capsules used to reach higher phosphate levels while keeping calories, sodium, potassium, and calcium constant. Fasting blood samples and 24-hour and random urine collections will be obtained at baseline and at the end of each phase to measure known and novel metabolites and biomarkers. The goal is to identify biomarkers responsive to dietary phosphorus and to build a compound phosphate overload index with high validity and reliability.
Why it matters
Potential benefit: If successful, this work could produce reliable biomarkers and a phosphate overload index that help detect early phosphate-related risk and guide dietary or clinical management in CKD.
How similar studies have gone: Previous feeding studies have linked dietary phosphate to changes in standard biomarkers, but developing and validating a compound phosphate overload index in CKD is largely novel and not yet proven.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: * 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 Exclusion Criteria: * 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) * 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
Where it's running
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University of Texas Southwestern Medical Center
Dallas, Texas, United States Recruiting
Study contacts
- Principal investigator: Jing Chen, MD — University of Texas Southwestern Medical Center
- Study coordinator: Alexandra Hartman
- Email: pack.utsw@utsouthwestern.edu
- Phone: 214-645-8294
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.