Sustainability of Vitamin D Levels After Repletion With Ergocalciferol In Chronic Kidney Disease Stage 5D

Inclusion Criteria: * Age ≥ 18 years * Activated vitamin D administration * On chronic hemodialysis for ≥ 6 months * Use of a synthetic biocompatible dialysis membrane * 25-hydroxyvitamin D levels \< 30 ng/mL * Corrected serum calcium \< 10.2 mg/dL * Serum phosphate \< 7 mg/dL * Iron replete (Ferritin \> 200 ng/mL and transferrin saturation \> 20%) Exclusion Criteria: * Current participation in any other investigational drug trial * Vitamin D deficiency due to a heredity disorder * Liver disease or failure * Current or past treatment with ergocalciferol or cholecalciferol ≥ 2000 IU per day (within the past 6 months) * Treatment with calcimimetics or bisphosphonates within the last 3 months * Treatment with anti-epileptics or other medications that can effect vitamin D metabolism * Malnutrition (serum albumin \< 2.5 mg/dL) * Pregnancy, positive pregnancy test or breastfeeding * Malignancy or other significant inflammatory disease * HIV/AIDS