Blood levels of active metabolites of vitamin D₃ in fracture repair in humans

Summary

Blood levels of the active metabolites of vitamin D₃, 25-hydroxycholecalciferol [25(OH)D₃], 1,25-dihydroxycholecalciferol [1,25(OH)₂D₃] and 24,25-dihydroxycholecalciferol [24,25(OH)₂D₃] were determined in seven patients. Two subjects suffered from delayed union of tibial fractures; one showed a delayed union after a proximal tibial osteotomy; one patient suffered from bilateral femoral neck fractures, of which one failed to unite and the other united late; two patients had multiple fractures that united normally; and one patient exhibited staged bilateral femoral neck fractures whose occurrence was separated by a short interval and which united without undue delay. The blood levels of 25(OH)D₃ were within the normal range. A relative decrease in 24,25(OH)₂D₃ values was noted in all patients, whereas in three subjects the decrease was absolute, to non-detectable levels. A decrease in 1,25(OH)₂D₃ levels was noted in only two patients. We postulate that these changes reflect the consumption of these metabolites during healing at the fracture site.