Changes of Serum Magnesium and Phosphate Concentrations during and after Hepatic Resections for Cirrhotic Patients

A prospective study to evaluate alternations in serum concentrations of total magnesium(TMg), ionized magnesium (iMg), inorganic phosphorus (PO4), lactic acid (LA), aspartate aminotransferase (AST), alanine aminotransferase (ALT) during and after liver resections in liver cirrhotic patients and their inter-relationships. Twenty-five patients were included with Child-Pughs B classification. Samples were taken before anesthesia induction, during liver resection, thiryt minutes after resection and reperfusion and daily for 3 days. TMg was adjusted for albumin concentration. Mg and PO4 supplementations were not given intraoperatively except for the magnesium found in the normal composition of Plasmalyte A, a multiple electrolyte fluid composition of pH 7.4 (6.5-8 )used for volume replacement. Results showed a significant decline in TMg, iMg and PO4 during liver resection (p=0.005 p= 0.008 p=0.068 respectively) and after resection (p=0.005 p=0.005 p=0.021 respectively).The decline of TMg exceeded the decline of iMg to below the normal laboratory reference ranges intraoperatively and postoperatively on day 1 in 15 patients. TMg correlated positively with iMg (r=0.55 p=0.01). Significant perioperative increase in LA, AST and ALT (p<0.05) were observed with a gradual decreased on day2 and 3. LA correlated positively with both AST and ALT (r=0.54, p<0.01 and r=0.53, p<0.01, respectively) but negatively with both TMg and iMg (r=-031 p=0.01, r= -0.22, p=0.09). Hypoalbuminaemia was frequently reported among this population. In conclusion total magnesium over estimated the incidence of hypomagnesaemia when significant hypoalbuminemia is present, ionised magnesium should be used instead. Intra-operative and post-operative hypophosphataemia occurs frequently. Monitoring and intravenous replacement is hence recommended. Lactate could be used as an indirect indicator for liver function. Possible preventive measures need to be investigated in future