Comparison of bone turnover markers in peripheral blood and bone marrow aspirate

The levels of most BTMs differed significantly between bone marrow and peripheral blood, while OPG was comparable. Levels of PINP, CTx, and BAP differed between compartments depending on concentration, suggesting bone marrow to represent a compartment separate from the general circulation. Unexpectedly, osteocalcin was lower in the marrow, a gradient that was independent of concentration. BTMs measured in bone marrow did not show any association with bone mineral density. Although further studies are needed to investigate potential explanatory causes of the differences, BTMs in bone marrow do not seem to contribute further to fracture risk assessment.