TY - JOUR
T1 - On measurements of glucagon secretion in healthy, obese, and Roux-en-Y gastric bypass operated individuals using sandwich ELISA
AU - Wewer Albrechtsen, Nicolai J.
AU - Kjeldsen, Sasha A. S.
AU - Jensen, Nicole J.
AU - Rungby, Jørgen
AU - Veedfald, Simon
AU - Bojsen-Møller, Kirstine N.
AU - Dirksen, Carsten
AU - Jensen, Christian Z.
AU - Martinussen, Christoffer
AU - Madsbad, Sten
AU - Holst, Jens J.
PY - 2022
Y1 - 2022
N2 - Glucagon is a key regulator of metabolism and is used in the diagnostic of neuroendocrine tumors. Accurate measurement of glucagon requires both extreme sensitivity and specificity since several peptides are derived from the same proglucagon precursor encoding part of the glucagon sequence and given that glucagon circulates in picomolar concentrations. A sandwich ELISA was recently developed and extensively evaluated; however, this method may not be accurate when measuring glucagon in patients with an enhanced production of proglucagon-derived peptides as seen after Roux-en-Y gastric bypass (RYGB). To overcome this, a modified version of the ELISA was developed. In this study, we evaluate an unmodified and a modified version of the ELISA in healthy individuals, individuals with obesity, and finally in two cohorts of patients following RYGB surgery using different nutrient stimuli to assess glucagon dynamics. Finally, in vitro spike-in recoveries using native glucagon and proglucagon-derived peptides were performed in buffer and in plasma. Our data support that both versions of the ELISA accurately capture endogenous and exogenous glucagon in healthy individuals and in individuals with obesity. However, the unmodified version of the assay may overestimate glucagon levels in patients following RYGB in line with minimal but consistent cross-reactivity to oxyntomodulin and glicentin that both are 50-fold increased after RYGB. Importantly, we did not find any changes between the two protocols at fasted conditions and therefore diagnostics of glucagonomas is not affected by the choice of assay procedure nor the surgical history of the patient (RYGB).
AB - Glucagon is a key regulator of metabolism and is used in the diagnostic of neuroendocrine tumors. Accurate measurement of glucagon requires both extreme sensitivity and specificity since several peptides are derived from the same proglucagon precursor encoding part of the glucagon sequence and given that glucagon circulates in picomolar concentrations. A sandwich ELISA was recently developed and extensively evaluated; however, this method may not be accurate when measuring glucagon in patients with an enhanced production of proglucagon-derived peptides as seen after Roux-en-Y gastric bypass (RYGB). To overcome this, a modified version of the ELISA was developed. In this study, we evaluate an unmodified and a modified version of the ELISA in healthy individuals, individuals with obesity, and finally in two cohorts of patients following RYGB surgery using different nutrient stimuli to assess glucagon dynamics. Finally, in vitro spike-in recoveries using native glucagon and proglucagon-derived peptides were performed in buffer and in plasma. Our data support that both versions of the ELISA accurately capture endogenous and exogenous glucagon in healthy individuals and in individuals with obesity. However, the unmodified version of the assay may overestimate glucagon levels in patients following RYGB in line with minimal but consistent cross-reactivity to oxyntomodulin and glicentin that both are 50-fold increased after RYGB. Importantly, we did not find any changes between the two protocols at fasted conditions and therefore diagnostics of glucagonomas is not affected by the choice of assay procedure nor the surgical history of the patient (RYGB).
KW - ELISA
KW - glicentin
KW - glucagon
KW - metabolism
KW - oxyntomodulin
KW - RYGB
U2 - 10.1080/00365513.2021.2016943
DO - 10.1080/00365513.2021.2016943
M3 - Journal article
C2 - 34935574
VL - 82
SP - 75
EP - 83
JO - Scandinavian Journal of Clinical & Laboratory Investigation
JF - Scandinavian Journal of Clinical & Laboratory Investigation
SN - 0036-5513
IS - 1
ER -