Regulation of histamine and diamine oxidase in patients undergoing orthotopic liver transplantation

Increased concentrations of the vasodilator histamine have been observed in patients undergoing abdominal surgery. The role of histamine during orthotopic liver transplantation (OLT) has only been studied in animals. The aim of this study was to measure plasma concentrations of histamine and its degrading enzyme diamine oxidase (DAO) in patients undergoing orthotopic liver transplantation, and assess whether histamine or DAO correlate with intraoperative noradrenaline requirements. Histamine and DAO concentrations were measured in 22 adults undergoing liver transplantation and 22 healthy adults. Furthermore, norepinephrine requirements during liver transplantation were recorded. Baseline concentrations of histamine and DAO were greater in patients, who underwent liver transplantation, than in healthy individuals (Histamine: 6.4 nM, IQR[2.9–11.7] versus 4.3 nM, IQR[3.7–7.1], p = 0.029; DAO: 2.0 ng/mL, IQR[1.5–4.1] versus <0,5 ng/mL, IQR[<0.5–1.1], p < 0.001). During liver transplantation, histamine concentrations decreased to 1.8 nM, IQR[0.5–4.9] in the anhepatic phase (p < 0.0001 versus baseline), and to 1.5 nM, IQR[0.5–2.9] after reperfusion (p < 0.0001 versus baseline). In contrast, DAO concentrations increased to 35.5 ng/ml, IQR[20–50] in the anhepatic phase (p = 0.001 versus baseline) and to 39.5 ng/ml, IQR[23–64] after reperfusion (p = 0.001 versus baseline), correlating inversely with histamine. Norepinephrine requirements during human liver transplantation correlated significantly with DAO concentrations in the anhepatic phase (r = 0.58, p = 0.011) and after reperfusion (r = 0.56; p = 0.022). In patients undergoing orthotopic liver transplantation, histamine concentrations decrease whereas DAO concentrations increase manifold. Diamine oxidase correlates with intraoperative norepinephrine requirements in patients undergoing OLT.