The goal of this project is to produce preliminary data on the effects of the commonly prescribed dietary phosphorus restriction on whole-body Calcium (Ca) and Phosphorus (P) balance and kinetics patients with CKD, to support a larger future clinical study. The specific aims are to determine intestinal Ca and P fractional absorption and 2) Ca and P balance and full kinetics, effect sizes variance estimates in patients with CKD on a low Ca diet with high P diet versus dietary P restriction. The hypothesis is that a high P diet, in the context of a typical low Ca diet, leads to P retention negative Ca balance, and that dietary P restriction modestly reduces P retention but does not negative Ca balance.
The study design is a randomized 2-period cross-over study. All outpatient and inpatient visits place at the Indiana CTSI Clinical Research Center located in IU Health University Hospital in Indianapolis, IN. Subjects will be randomly assigned to controlled diets of either low Ca/high P (LCa/HP) or low (LCa/LP) for a 1-week, outpatient diet equilibration period, followed by 1-week inpatient full balance that includes a 48-hour Ca and P absorption testing protocol. After a 1-3 week washout subjects will crossover to the other diet regimen
