PTH and systemic sclerosis: Serum levels of calcium (2.41 ± 0.14 vs. 2.32 ± 0.11 mmol/l; p = 0.001) and PTH (5.47 ± 2.84 vs. 4.14 ± 1.38; p = 0.008) were significantly higher in SSc patients than in controls.