The relation between vitamin-D (VD) status and healing after hip fracture had not been sufficiently addressed. Currently serum total 25-hydroxy-VD (t-25OHD) is the most widely used indicator of VD status. It is unclear whether free or bioavailable VD are better markers of 25OHD availability for tissues. Validity of overall cut-off values of t-25OHD is limited.
Objectives: (1) Assess serum levels of circulating forms of 25OHD in patients with hip fracture (PwHF: N = 199) compared to active controls without history of fracture (N = 102); (2) determine relationship between 25OHD fractions and functional performance after surgery (FPAS) and survival. The t-25OHD; VD binding protein and albumin levels were measured. Comorbidities; lifestyle; FPAS and survival were recorded at seven months. VD deficiency occurred more frequently in PwHF than in controls (72% vs. 38%). Patients with better FPAS showed higher 25OHD in all fractions than with poor FPAS. Controlled by lifestyle; 25OHD levels were independent predictive factors (p < 0.001). Good FPAS values forecasted longer survival (OR: 6.5CI:3.2⁻13.3; p < 0.0001). All 25OHD forms showed a tendency to predict survival. Mortality rate decreased to 8% in individuals with t-25OHD levels of >22.6⁻39.5 nmol/L and increased to 14% with >40 nmol/L. These observations highlight the importance of serum 25OHD assessment and moderate VD substitution for healing and survival.
Keywords: bioavailable-25OHD; comorbidities; cut off values; free-25OHD; healing; hip fracture; survival; total-25OHD.