CALCA and pulmonary arterial hypertension: This indicated that calcitonin and SOST serum levels were both significantly increased in all three SSc subgroups compared to the HCs (n = 20), while the calcitonin level was much higher in the SSc with PAH group (n = 19) and the SOST level was much lower in the SSc with ILD group (n = 22) than in the SSc without PAH and ILD group (n = 17).