CTSZ and Osteopenia: The significant increases in cathepsin Z mRNA levels in osteopenia/osteoporosis were also evident when 11 participants who were below the age of 50 were excluded from the analysis (Fig. 1b) (one-way ANOVA (F(2,74) = 10.9), P < 0.0001; non-osteoporotic control group vs osteopenia, 95% CI = −0.39 to −0.051, P = 0.0113; non-osteoporotic control group vs osteoporosis, 95% CI = −0.604 to −0.234, P = < 0.0001; osteopenia vs osteoporosis, 95% CI = −0.324 to −0.072, P = 0.0025, post hoc Bonferroni correction).