Vitamin D2 or ergocalciferol can replace vitamin D3, but its dosage must be a higher international unit: one unit of vitamin D3 is equal to 4 units of vitamin D2. A proper interval of administration should take 200,000 IU per day. The 123
cases enrolled for study, every case had blood levels of 25 (OH) D and blood calcium checked before intake of vitamin D2
followed by a second check after 2 months. The means of before-intake group was 31.92 ng/ml and after-intake group was 48.62 ng/ml; the pair sample mean was 0.001. We found the level of 25 (OH) D was greater than 70 ng/ml (max = 90), 3.2 percent. Twelve cases showed no response, 9.6 percent. No cases of hypercalcemia or allergic phenomenon were noted.
Before the study, we tried a random dosage of 200,000 IU per week and found the pair mean showed nothing significant (p
= 0.052). In practice, the dosage of 200,000 IU of vitamin D2 is suitable for treatment of vitamin D deficiency, but for longterm
treatment, dosage should be adjusted by monitoring the levels of 25 (OH) D from time to time.

Keywords: Ergocalciferol, Vitamin D2