Phosphate Assessment in Chronic Kidney Disease Patients Study

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.

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.