how long does it take to build vitamin d back up?
For children 1-18 years of age who are vitamin D deficient, we suggest treatment with 2,000 IU/d of vitamin D3 for at least six weeks or with 50,000 IU once a week for at least six weeks to achieve a blood level of 25(OH)D above 30 ng/mL, followed by maintenance therapy of 600-1,000 IU/day.