PTH and Osteopenia: Furthermore, we found that for the osteopenia group, greater vitamin D levels were associated with greater femoral neck BMD (<i>p</i> = 0.020) and total hip BMD (<i>p</i> = 0.008) and lower β-CTX (<i>p</i> < 0.001), OC (<i>p</i> < 0.001), and PTH (<i>p</i> < 0.001).