Fetuin-A serum levels are not correlated to kidney function in long-lived subjects

OBJECTIVES: Serum Fetuin A has been identified as an inhibitor of ectopic calcification. It is reduced in subjects with chronic kidney disease (CKD) and it has been proposed as a potential link between CKD and the higher prevalence of arterial calcification observed in these patients. During aging both the stiffening of arterial wall due to calcification and a decline in kidney function are frequent. The aim of the study is to investigate if Fetuin A serum levels are associated with aging and with AHSG T256S polymorphism. Moreover, we aim at investigate whether serum Fetuin A is correlated to kidney function in this setting of senescence. DESIGN AND METHODS: 256 health long-lived subjects (age 92 [81-100]) were recruited for the study. Serum Fetuin A was evaluated by ELISA, Cystatin C by immune-nephelometry. AHSG T256S was determinated by PCR-RFLP. RESULTS: Serum Fetuin A shows a significant correlation with age (r=0.20; P=0.0048). AHSG TS and SS genotypes are associated to lower levels of serum protein (0.27 [0.19-0.29] g/L vs 0.42 [0.32-0.49] g/L; P<0.027 and 0.34 [0.25-0.41] g/L vs 0.42 [0.32-0.49] g/L; P<0.001, respectively). No significant correlation between Fetuin A and Cystatin C was observed. CONCLUSIONS: Serum Fetuin A increases with age in elder individuals and subjects with the TS or SS AHSG polymorphism have lower levels of the circulating protein. No correlation with kidney function decline was observed. Other mechanisms should be investigated to explain the increase of Fetuin A with age.