Serum FGF-23 and klotho levels in patients with systemic sclerosis and its relationship with carotid intima media thickness

Aim: Systemic sclerosis (SSc) is an uncommon connective tissue disease characterized by skin fibrosis. Fibrosis of internal organs such as the lungs and heart is also involved in SSc via complex pathophysiological mechanisms. Increased serum fibroblast growth factor (FGF-23) is related to cardiac hypertrophy and fibrosis in chronic kidney disease. We investigated the likely role of FGF-23 and Klotho in SSc and their link with carotid intima-media thickness (CIMT) in these patients. Material and Methods: A total of 86 participants (43 SSc patients between 18 and 65 years old and 43 healthy volunteers) were included in the study. We recorded patients' demographic data, clinical features, and biochemical and hormonal parameters. A radiologist performed the ultrasonographic examination of CIMT. The chi-square test and Fisher's exact test were utilized for comparisons of categorical variables. Results: In SSc patients, the FGF-23 level was significantly higher. According to our subgroup analysis, the patients with interstitial lung disease (ILD) had significantly higher FGF-23 levels than patients without ILD (p=0.031). However, the levels of alpha-klotho were similar between the two groups. The mean CIMT in SSc patients was significantly higher than in the control group (0.62 +/- 0.11 vs. 0.49 +/- 0.10, mm; p<0.001). There were no correlations between FGF-23 (p=0.086, r=0.265), alpha-klotho (p=0.820, r=0.036), FGF23/alpha-klotho (p=0.90, r=0.019), and CIMT in SSc patients. Discussion: FGF-23 can play a culprit role in the pathogenesis of SSc. It was not related to CIMT as a predictor of atherosclerosis. It can predict lung involvement and disease prognosis.