PTH and Osteopenia: In the model corrected for age, gender, height, smoking frequency, levels of blood vitamin D, PTH, ALP, FEV1 (%), and physical inactivity level, the presence of sarcopenia increased the risk of osteopenia, osteoporosis, and a low BMD (OR = 3.227, 95% CI = 2.125–4.899, p < 0.001, OR = 6.952, 95% CI = 3.418–14.139, p < 0.001, and OR = 3.495, 95% CI = 2.315–5.278, p < 0.001, respectively).