Bone turnover marker concentrations for both Munich and Wesel were performed by the Modular-System (Roche) in the same lab. Intra- and inter-assay coefficients of variation for the precision of quality controls varied between 3.2% and 2.9% for the concentrations of 23.7 and 123.1 ng/mL for osteocalcin, and between 4.7% and 4.8% for the concentrations of 343 and 792 ng/mL for CTx, respectively.