Serum and bone vitamin D metabolites in elective patients and patients after fracture

Vitamin D metabolite levels were measured in serum and bone samples obtained from 27 patients undergoing elective bony procedures and from 28 patients operated on after a fracture. Serum 25 hydroxyvitamin D3 (25-OH-D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) did not differ significantly between the elective and fracture patients, but serum 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) was significantly reduced in the fracture patients. Very little 25-OH-D3 was found in bone, although it was the major vitamin D metabolite in serum (90%). In elective patients bone levels of 24,25(OH)2D3 and 1,25(OH)2D3 were similar to those in serum; however, in bone from around pertrochanteric fractures, but not from subcapital or patellar fractures, the concentrations of these compounds were considerably increased. These findings may shed light on the mechanism of callus formation and on the role of vitamin D metabolites in bone healing.