Inclusion Criteria: Pathologic diagnosis of newly diagnosed AML (excluding acute promyelocytic leukemia [APL]) Patients undergoing intensive induction therapy (equivalent of 7+3, cytarabine, daunorubicin, etoposide [ADE] or high-dose cytarabine containing regimens) Subnormal 25(OH)-D3 levels (< 32 ng/mL) Serum calcium =< upper limit of normal Demonstrate the ability to swallow and retain oral medication Patients of child-bearing potential must agree to use acceptable contraceptive methods (e.g., double barrier) during treatment Patient or legal representative must understand the investigational nature of this study and sign an Independent Ethics Committee/Institutional Review Board approved written informed consent form prior to receiving any study related procedure Exclusion Criteria: Patients should not have a history of nephrocalcinosis Patients should not have received bisphosphonate treatment within 28 days before study entry Pregnant or nursing female patients Unwilling or unable to follow protocol requirements Any condition which in the Investigator's opinion deems the patient an unsuitable candidate to receive study drug Received an investigational agent within 30 days prior to enrollment Patients who cannot be discontinued from cimetidine, thiazide diuretics and/or heparin Patients who are on magnesium based antacids who cannot be offered an alternative regimen