Decrease in Vitamin D Binding Protein in Acute Fractures Does Not Affect Vitamin D Levels.

Backgroud: Vitamin D binding protein (VDBP) is a major transport protein for vitamin D (VD) and its level is known to change with systemic inflammatory responses. We aimed to investigate whether acute musculoskeletal injury affects VDBP levels and thus also impacts VD levels.

Methods: We measured serum VDBP levels, free 25(OH)D, and total 25(OH)D in 2 age-matched (mean age, 56 years) female groups: one diagnosed with a wrist fracture (n = 35) and the other consisting of healthy volunteers (n = 35). We tested differences between the groups and correlations between the measurements.

Results: VDBP levels were significantly lower in the wrist fracture group (350.4 ± 151.2 µg/mL) than in the healthy volunteer group (478.6 ± 47.0 µg/mL, p < 0.001). However, the free and total 25(OH)D levels were not significantly different between the groups. The correlation between free and total 25(OH)D levels was strong in the healthy volunteer group (R = 0.885) but moderate in the wrist fracture group (R = 0.605).

Conclusions: The lower VDBP levels in wrist fracture patients compared to the healthy volunteers indicate that acute musculoskeletal injuries affect VDBP levels. However, the decrease in the VDBP levels did not affect free and total VD levels. Further research might determine whether the current measurement of total 25(OH)D in fracture patients can reflect the VD status.