The primary goal of this research study is to learn if patients with autosomal recessive polycystic kidney disease (ARPKD) are at risk for brain aneurysms or cardiovascular abnormalities.Participants in this study will involve patients that have a clinical diagnosis of ARPKD.The study will also involve a comparison group of healthy individuals that have no history of kidney or cardiac conditions.

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.

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The primary goal of this research study is to see if new types of magnetic resonance imaging (MRI) can be used to measure liver health in children with autosomal recessive polycystic kidney disease (ARPKD) compared to healthy controls. Both children with ARPKD and healthy children, aged 6 years and above can participate.

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.