Ferric Citrate and Chronic Kidney Disease in Children

We will conduct a double-blind, randomized, placebo-controlled trial to assess the effects of therapy with ferric citrate (FC) on changes in intact FGF23 levels (iFGF23, primary endpoint) aged 6-18 years of either sex with chronic kidney disease (CKD) stages 3-4 and age-appropriate normal serum phosphate levels. Participants will be randomized to one of the two groups: 1) FC or 2) FC placebo. Participants will be recruited from 20 core clinical sites. Schedule of Intervention: During the 12-month trial, participants will be given a daily fixed weight-based dose of FC. Schedule for data collection/analyses to be performed: Blood for primary outcome assessments will be collected at screening, baseline and at months 3, 6, 9, 12. Blood for safety assessments will be collected at the the months 1, 2, 3, 6, 9, 12. The primary analyses for this 2-arm trial will compare log-transformed iFGF23 values over 12 months between the treatment and the placebo arms. The analysis will use a linear mixed-effects model, including stratification factors CKD stage and urine protein to creatinine ratio, with random participant effects accounting for repeated measurements, and a fixed treatment effect, which interacts with a time indicator (Months 3-12 vs. Baseline/Screening). Primary objectives: * To assess the effects of therapy with FC on iFGF23 levels * To determine safety and tolerability of FC. Secondary objectives: • To assess the effects of FC on anemia and indices of mineral and bone metabolism. Primary Endpoint: • iFGF23 level Safety and Tolerability Endpoints: • Ability to safely tolerate FC Secondary Endpoints: * Anemia * Indices of mineral and bone metabolism This is a Phase 2 study with participation from 20 sites that will take 36 months to complete enrollment and a total of 48 months to complete data collection with each participant being part of the study for 12 months. Study website: fit4kid.dgsom.ucla.edu