CTSK and osteoporosis: qPCR analysis showed that the expression levels of β-catenin, Wnt10b, Lrp5, Lrp6, OPG, RANKL, and Runx2 were the lowest in the model group, while the expressions of the negatively regulated genes, DKK1, ALP, CTSK, and TRACP, increased, indicating successful construction of our model of secondary osteoporosis.