The aim of this study is to evaluate whether the optimal vitamin D level is achieved after taking recommended dose in vitamin D deficient patients.

This was a retrospective study. Women (n=52) first diagnosed with osteoporosis were recruited in outpatient clinic. They were recommended to be exposed to sun light for more than 30 min a day. Subjects were divided into 3 groups according to serum 25-hydroxy-vitamin D₃ (25-[OH]D₃) status: deficiency (less than 20 ng/mL), insufficiency (20-30 ng/mL) and sufficiency (30 ng/mL or more). Insufficient and sufficient patients received the recommended dose (1,000 IU/day) but deficient patients received recommended or double dose (1,800-2,000 IU/day). We compared 25-(OH)D levels at baseline and after vitamin D supplementation for 3 months.

Median (interquartile range) serum 25-(OH)D concentration at baseline was 15.10 (13.30-16.97) ng/mL and the proportion of deficient, insufficient and sufficient groups were 69.2%, 23.1%, and 7.7% respectively. The optimal 25-(OH)D level (30 ng/mL or more) was achieved in 83.3% of insufficient patients with the recommended dose and was did in 55.6% of deficient patients with recommended dose ( P =0.117). However, 88.9% of the deficient patient with double dose achieved optimal level ( P =0.030).

About 44% of vitamin D deficient patients did not attain the optimal level of serum 25-(OH)D despite recommended daily intake of vitamin D to 1,000 IU in patients with osteoporosis. Follow-up of serum 25-(OH)D levels may be required for vitamin D supplementation in vitamin D deficient patients with osteoporosis.