Postoperative serum phosphate drop is an early marker of liver growth after ALPPS stage 1 and predicts outcome after ALPPS stage 2

Background: The accelerated hypertrophy after ALPPS stage-1 is based on rapid cell devision. This process demands tremendous amounts of phosphate for the synthesis of nucleotidetriphosphates during DNA replication. The aim of this study was to analyze whether changes in serum phosphate levels are associated with liver growth and posthepatectomy liver failure (PHLF) after ALPPS. Methods: Serum phosphate changes within the first 7 postoperative days (POD) after ALPPS stage-1 were assessed in 49 patients. All patients underwent volumetric imaging of the future liver remnant before ALPPS and at POD 7 after stage-1. The association of serum phosphate drop (PD) after ALPPS stage-1 with liver hypertrophy after stage-1 and with incidence of PHFL after stage-2 were investigated. Results: After ALPPS stage-1, serum phosphate levels decreased from 1.1 mmol/l (IQR 0.92-1.2) preoperatively to a nadir of 0.7 mmol/l (IQR 0.54-1.02; p< 0.001). The median PD was 40.9%/day (IQR -68.9 to -17.3%/d). Patients with a PD >40%/day showed significantly accelerated liver hypertrophy (median +264ml; IQR 196-347ml) after ALPPS stage-1 as compared with patients with a drop ≤40%/day (median +183ml; IQR 112-211ml; p=0.018). ROC analysis confirmed a PD >40%/day after stage-1 as a predictor of PHLF after ALPPS stage-2 according to 50-50 (AUC 0.769, p=0.015) and ISGLS criteria (AUC 0.760, 0.006). Conclusion: Serum PD represents a novel early predictor of liver growth and PHLF in patients undergoing ALPPS.