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Optimal Vitamin D Levels

CAPTION: July 2021

Q. What dose of vitamin D do I need to prescribe my patients for optimal levels of serum 25-hydroxyvitamin D?
The Institute of Medicine (IOM) define vitamin D status into three categories:[1]
1. Deficiency: serum 25-hydroxyvitamin D values <30 nmol/L
2. Insufficiency: serum 25-hydroxyvitamin D values of 30 to 49 nmol/L
3. Sufficiency: serum 25-hydroxyvitamin D values of 50 to 125 nmol/L
Levels above 100 nmol/L are considered to be ideal. [2]

In cases of vitamin D deficiency or insufficiency, as indicated by serum 25-hydroxyvitamin D, it is advised to supplement 1,000 IU (25 μg) of colecalciferol daily for 3 months to increase serum 25-hydroxyvitamin D levels by 25 nmol/L. After 3 months of supplementation it is recommended to re-test serum 25-hydroxyvitamin D and alter treatment as required.

1. Looker AC, Johnson CL, Lacher DA, Pfeiffer CM, Schleicher RL, Sempos CT. Vitamin D status: United States, 2001-2006. NCHS Data Brief. 2011(59):1-8.
2. Cannell JJ, Hollis BW. Use of vitamin D in clinical practice. Altern Med Rev. 2008 Mar;13(1):6-20. PMID: 18377099.