The purpose of this NIH-funded placebo-controlled clinical trial is to determine how well ferric citrate will lower FGF23, correct anemia and iron levels in the blood, and maintain normal levels of phosphate in children with CKD. Chronic Kidney Disease (CKD) is a condition in which the kidney function is decreased. Fibroblast Growth Factor 23 (FGF23) is a hormone that regulates blood phosphate levels. High FGF23 levels are linked with worsening of kidney, bone & heart health. Ferric Citrate is an oral medication that decreases the absorption of dietary phosphate by the gut, lowers FGF23 levels and raises iron stores in the body. Ferric Citrate is approved in adults with CKD but has not yet been studied in children.

For more information visit www.fit4kidstudy.com

The purpose of this study is to identify components of a physical activity intervention that are effective and meaningful to teenagers with chronic kidney disease (CKD).

Participants will be assigned to 1 of the 16 study groups and will be asked to wear a Fitbit. Participants will also be given a step count goal, answer questionnaires, and complete hand grip strength assessments.

Participants may also be asked to have one-on-one meetings with an exercise coach.

All visits may be completed remotely.