Effects of Ergocalciferol on Erythropoetin Stimulating Agent Dose

Inclusion Criteria: * Chronic kidney disease * Age: \>18yo * Stable Hemoglobin (Hgb) for 1 month on stable dose of erythropoietin for 1 month (defined as erythropoietin dose within 15% of previous months erythropoietin dose) * Unchanged maintenance oral or intravenous (IV) iron therapy for 1 month * Serum 25-hydroxy Vitamin D levels \< 30 ng/mL * History of 25-hydroxy Vitamin D levels \< 30 ng/mL currently on ergocalciferol replacement Exclusion Criteria: * On hemodialysis * Chronic kidney disease 5 * Hypercalcemic (Calcium level \> 11mg/dL) * Pregnant female * Iron deficient (iron saturation \< 20%, Ferritin \< 100ng/mL) * Presence of active malignancy * Presence of active infections * Presence of active inflammatory properties * Presence of blood dyscrasias * Active bleeding or bleeding within the past 3 months (other than menses) * B12 deficiency * Folate deficiency * Blood transfusion during participation * Parathyroid levels exceeding the expected levels allowed for the stage of a subjects Chronic kidney disease (Target Parathyroid in: Chronic kidney disease 3 35-70 pg/mL, Chronic kidney disease 4 70-110 pg/mL)