Subjects will be randomized and assigned to one of the treatment groups (D2 or D3). Subjects will be dispensed a supply of 1.25 mg cholecalciferol/ergocalciferol tablets, depending on their randomization outcome. The number of pills dispensed and medication instructions will be determined by their 25OHD level and K/DOQI guidelines. Both Study personnel and subject will be blinded to randomization group.