Development and Application of Mass Spectroscopy Assays for Nε-(1-Carboxymethyl)-L-Lysine and Pentosidine in Renal Failure and Diabetes

• Published in: The journal of applied laboratory medicine Vol. 5; no. 3; p. 558
• Main Authors: O'Grady, Katherine L, Khosla, Sundeep, Farr, Joshua N, Bondar, Olga P, Atkinson, Elizabeth J, Achenbach, Sara J, Eckhardt, Brittany A, Thicke, Brianne S, Tweed, Amanda J, Volkman, Tammie L, Drake, Matthew T, Hines, Jolaine M, Singh, Ravinder J
• Format: Journal Article
• Language: English
• Published: England 01.05.2020
• Subjects: renal failure; advanced glycation endproducts; diabetes; mass spectroscopy
• ISSN: 2576-9456; 2475-7241
• DOI: 10.1093/jalm/jfaa023

Advanced glycation end products (AGEs) are formed via the nonenzymatic glycation of sugars with amino acids. Two AGEs, Nε-(1-carboxymethyl)-L-Lysine (CML) and pentosidine, have been observed to be elevated in subjects suffering from a multitude of chronic disease states, and accumulation of these compounds may be related to the pathophysiology of disease progression and aging. We describe here the development and validation of a specific and reproducible LC-MS/MS method to quantify CML and pentosidine in human serum with lower limits of quantitation of 75 ng/mL and 5 ng/mL, respectively. The analyte calibration curve exhibited excellent linearity at a range of 0-10 900 ng/mL for CML and 0-800 ng/mL for pentosidine. High-low linearity of 5 serum pairs was assessed, with a mean recovery of 103% (range 94-116%) for CML, and 104% (range 97-116%) for pentosidine. Serum concentrations of CML and pentosidine were quantified in 30 control and 30 subjects with chronic renal insufficiency. A significant increase in both analytes was observed in renal failure compared to control subjects (2.1-fold and 8.4-fold, respectively; P < 0.001 for both). In a separate cohort of 49 control versus 95 subjects with type 2 diabetes mellitus (T2DM), serum CML but not serum pentosidine, was significantly elevated in the T2DM patients, and CML was also correlated with glycemic control, as assessed by hemoglobin A1c (r = 0.34, P < 0.001). These mass spectroscopy-based assays for serum CML and pentosidine should be useful in accurately evaluating circulating levels of these key AGEs in various disease states.