NCT07368946 · University of Texas Southwestern Medical Center
Phosphate Assessment in Chronic Kidney Disease Patients Study
(PACK)
What this study is about
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).
View original scientific description
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.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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
- Dallas, Texas
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jan 28, 2026 · Source of record for eligibility and locations