KL and systemic sclerosis: At t0, there are no significant differences of FGF-23 [18.6 ± 4.7 pg/ml versus 16.2 ± 6.9 pg/ml, p > 0.05], Klotho [4.8 ± 0.9 pg/ml versus 5.6 ± 0.6 pg/ml, p > 0.05] and NGAL [20.7 ± 2.9 pg/ml versus 21.2 ± 2.4 pg/ml, p > 0.05] in SSc patients with RRI ≥ 0.70 compared to SSc patients with normal RRI (Fig. 2D-F).