The goal of this study is to better understand vitamin D catabolism and how it is affected by CKD and race. Specifically, the study team will evaluate the metabolic clearance of 25-hydroxyvitamin D3 in individuals with varying degrees of CKD and among participants who self-report race as Caucasian, African American or African. The long-term goal of this work is to enhance the clinical evaluation and treatment of impaired vitamin D metabolism.