Specificity and sensitivity of commercially available assays for glucagon-like peptide-1 (GLP-1): Implications for GLP-1 measurements in clinical studies

TY - JOUR

T1 - Specificity and sensitivity of commercially available assays for glucagon-like peptide-1 (GLP-1)

T2 - Implications for GLP-1 measurements in clinical studies

AU - Bak, Monika Judyta

AU - Albrechtsen, Nicolai Jacob Wewer

AU - Pedersen, Jens

AU - Knop, Filip Krag

AU - Vilsbøll Lauritsen, Tina

AU - Jørgensen, Nils B

AU - Hartmann, Bolette

AU - Deacon, Carolyn F.

AU - Dragsted, Lars Ove

AU - Holst, Jens Juul

N1 - CURIS 2014 NEXS 349

PY - 2014/11/1

Y1 - 2014/11/1

N2 - Aims: To evaluate the performances of commercially available glucagon-like peptide-1 (GLP-1) assays and the implications for clinical studies. Methods: Known concentrations (5-300pmol/l) of synthetic GLP-1 isoforms (GLP-1 1-36NH2, 7-36NH2, 9-36NH2, 1-37, 7-37 and 9-37) were added to the matrix (assay buffer) supplied with 10 different kits and to human plasma, and recoveries were determined. Assays yielding meaningful results were analysed for precision and sensitivity by repeated analysis and ability to discriminate low concentrations. Endogenous GLP-1 levels in clinical samples were assessed using three commercial kits. Results: The USCN LIFE assay detected none of the GLP-1 isoforms. The active GLP-1 enzyme-linked immunosorbent assays (ELISAs) from Millipore and DRG appeared identical and were specific for intact GLP-1 in buffer and plasma. The Meso Scale Discovery (MSD) total GLP-1 kit detected all six GLP-1 isoforms, although recovery of non-active forms was incomplete, especially in plasma. Millipore total GLP-1 ELISA kit detected all isoforms in buffer, but mainly amidated forms in plasma. The Alpco, Phoenix and Bio-Rad kits detected only amidated GLP-1, but the Alpco kit had a limited measurement range (30pmol/l), the Phoenix kit had incomplete recovery in plasma and the Bio-Rad kit was insensitive (detection limit in plasma 40pmol/l). The pattern of postprandial GLP-1 responses in clinical samples was similar between the kits tested, but the absolute concentrations measured varied. Conclusions: The specificity and sensitivity of commercially available kits for the analysis of GLP-1 levels vary considerably. This should be taken into account when selecting which assay to use and when comparing data from different studies.

AB - Aims: To evaluate the performances of commercially available glucagon-like peptide-1 (GLP-1) assays and the implications for clinical studies. Methods: Known concentrations (5-300pmol/l) of synthetic GLP-1 isoforms (GLP-1 1-36NH2, 7-36NH2, 9-36NH2, 1-37, 7-37 and 9-37) were added to the matrix (assay buffer) supplied with 10 different kits and to human plasma, and recoveries were determined. Assays yielding meaningful results were analysed for precision and sensitivity by repeated analysis and ability to discriminate low concentrations. Endogenous GLP-1 levels in clinical samples were assessed using three commercial kits. Results: The USCN LIFE assay detected none of the GLP-1 isoforms. The active GLP-1 enzyme-linked immunosorbent assays (ELISAs) from Millipore and DRG appeared identical and were specific for intact GLP-1 in buffer and plasma. The Meso Scale Discovery (MSD) total GLP-1 kit detected all six GLP-1 isoforms, although recovery of non-active forms was incomplete, especially in plasma. Millipore total GLP-1 ELISA kit detected all isoforms in buffer, but mainly amidated forms in plasma. The Alpco, Phoenix and Bio-Rad kits detected only amidated GLP-1, but the Alpco kit had a limited measurement range (30pmol/l), the Phoenix kit had incomplete recovery in plasma and the Bio-Rad kit was insensitive (detection limit in plasma 40pmol/l). The pattern of postprandial GLP-1 responses in clinical samples was similar between the kits tested, but the absolute concentrations measured varied. Conclusions: The specificity and sensitivity of commercially available kits for the analysis of GLP-1 levels vary considerably. This should be taken into account when selecting which assay to use and when comparing data from different studies.

U2 - 10.1111/dom.12352

DO - 10.1111/dom.12352

M3 - Journal article

C2 - 25041349

SN - 1462-8902

VL - 16

SP - 1155

EP - 1164

JO - Diabetes, Obesity and Metabolism

JF - Diabetes, Obesity and Metabolism

IS - 11

ER -