Detection of Free Advanced Glycation End Products in Vivo during Hemodialysis

Advanced glycation end products (AGEs) are often regarded as glycotoxins, which are normally removed by the kidney. Patients with end-stage renal failure rely on hemodialysis (HD) treatment to eliminate these compounds. In the present work, a highly selective LC-MS/MS method was used for quantitation of AGE levels in plasma and in dialysis fluids of HD patients, with a focus on AGE-free adducts. A broad range of 19 amino acid modifications was identified and quantitated. It was expected that the AGE-free adducts are successfully eliminated by dialysis treatment. Indeed, with a mean elimination rate of 71%, this assumption proved to be valid for all target analytes with the exception of pyrraline, which showed an opposite behavior. Here, plasma and dialysate levels increased during the treatment by about 59%. The notions that pyrraline was formed in high amounts in the patient’s bloodstream (I) after intake of the corresponding precursor compound 3-deoxyglucosone with the dialysis fluid or (II) by catalyti...