Hypophosphataemia after major hepatectomy and the risk of post-operative hepatic insufficiency and mortality: an analysis of 719 patients

Background: Hypophosphataemia after a hepatectomy suggests hepatic regeneration. It was hypothesized that the absence of hypophosphataemia is associated with post-operative hepatic insufficiency (PHI) and complications. Methods: Patients who underwent a major hepatectomy from 2000-2012 at a single institution were identified. Post-operative serum phosphorus levels were assessed. Primary outcomes were PHI (peak bilirubin >7 mg/dl), major complications, and 30- and 90-day mortality. Results: Seven hundred and nineteen out of 749 patients had post-operative phosphorus levels available. PHI and major complications occurred in 63 (8.8%) and 169 (23.5%) patients, respectively. Thirty-and 90-day mortality were 4.0% and 5.4%, respectively. The median phosphorus level on post-operative-day (POD) 2 was 2.2 mg/dl; 231 patients (32.1%) had phosphorus >2.4 on POD2. Patients with POD2 phosphorus >2.4 had a significantly higher incidence of PHI, major complications and mortality. On multivariate analysis, POD2 phosphorus >2.4 remained a significant risk factor for PHI [(hazard ratio HR): 1.78; 95% confidence interval (CI): 1.02-3.17; P = 0.048], major complications (HR: 1.57; 95% CI: 1.02-2.47; P = 0.049), 30-day mortality (HR: 2.70; 95% CI: 1.08-6.76; P = 0.034) and 90-day mortality (HR: 2.51; 95% CI: 1.03-6.15; P = 0.044). Similarly, patients whose phosphorus level reached nadir after POD3 had higher PHI, major complications and mortality. Conclusion: Elevated POD2 phosphorus levels >2.4 mg/dl and a delayed nadir in phosphorus beyond POD3 are associated with increased post-operative hepatic insufficiency, major complications and early mortality. Failure to develop hypophosphataemia within 72 h after a major hepatectomy may reflect insufficient liver remnant regeneration.