Decreased serum carnitine is independently correlated with increased tissue accumulation levels of advanced glycation end products in haemodialysis patients

Aim: There is accumulating evidence that advanced glycation end products (AGE) play a role in cardiovascular disease (CVD) in patients with haemodialysis (HD). Carnitine deficiency is frequently observed in HD patients, which may also contribute to CVD. In this study, we examined whether carnitine deficiency was independently associated with increased tissue accumulation levels of AGE in HD patients. Methods: One hundred and twenty-nine HD patients underwent determinations of blood chemistries including serum level of carnitine. Tissue AGE levels were evaluated by measuring skin autofluorescence with an AGE-reader. Results: Serum carnitine levels were significantly lower, while skin AGE levels were significantly higher in HD patients compared with healthy controls (P < 0.001). In univariate analysis, beta(2)-microglobulin (beta(2)-MG) and carnitine (inversely) were correlated with skin AGE levels. Multiple stepwise regression analysis revealed that carnitine levels were one of the independent determinants of skin AGE levels (P = 0.024). When beta(2)-MG-adjusted skin AGE levels were stratified by serum carnitine levels, a statistical significance and dose-response relationship were observed (P = 0.043). Furthermore, skin AGE levels were one of the independent determinants of serum carnitine levels as well (P = 0.012). Conclusion: The present study demonstrated that decreased carnitine levels were independently associated with increased skin AGE levels in HD patients. Since carnitine is reported to inhibit the formation of AGE in vitro, our study suggests that supplementation of carnitine may be a therapeutic target for preventing the accumulation of tissue AGE and subsequently reducing the risk of CVD in HD patients.