PTH and chronic obstructive pulmonary disease: Phosphate (1.0 ± 02 vs. 1.1 ± 0.2 mmol/L; p = 0.027), PTH (54.2 ± 29.4 vs. 68.7 ± 31.8 pg/mL; p = 0.002) and iFGF23 (46.3 ± 29.0 vs. 57.5 ± 33.5 pg/mL; p = 0.026 ) levels were significantly lower in COPD patients compared with controls.