Serum ionized magnesium changes during and immediately after liver transplantation

Alterations in magnesium (Mg) homeostasis during and after orthotopic liver transplantation are common. The purpose of this study is to compare total Mg (TMg), calculated ionized Mg (cMg++) and measured ionized Mg (mMg++) during and immediately following liver transplantation. The newly developed first generation ion selective electrode analyzer, AVL 988-4, was used to measure mMg++ in 63 serum samples from 3 transplant recipients and 48 serum samples from 48 healthy volunteers. Analysis was divided into intraoperative (stages 1 to 3) and postoperative periods. Decreased TMg, cMg++ and mMg++ levels were observed intraoperatively and > 2 weeks postoperatively. The cMg++ levels were consistently higher than mMg++, presumably owing to the fact that the equation used for the calculation does not take complex-Mg++ into account. A better correlation was observed between mMg++ and cMg++ in the transplant group (r = 0.87 to 0.99) compared to controls (r = 0.74). The usefulness of direct measurement of Mg++ in liver transplantation remains to be determined.