Serum delipidation but not high-speed centrifugation is effective in clearing lipemia interference in serum lipase activity measurement.

Abstract

Background: Acute pancreatitis is commonly followed by hypertriglyceridemia. Most current diagnostic guidelines indicate that lipase should be preferred over amylase. However, grossly lipemic samples may interfere with routine laboratory methods for measurement of serum lipase activity. We aimed to evaluate the accuracy of lipase activity measurement by a method with declared lipemia interference in lipemic samples cleared by two different techniques: high speed centrifugation and delipidation using alpha- cyclodextrin (non- ionic natural macrocyclic polymer of glucose). Materials and methods: Thirty-four lipemic serum samples with triglyceride concentration range of 4.27 to 124.6 mmol/L were used in this study. Lipase activity was measured by two measuring principles: Roche Lipase colorimetric method (elective reference laboratory method accurate for lipemic samples), in native lipemic samples on Roche Cobas Integra 400 plus analyzer. Beckman Coulter colorimetric method (lipemia interference >10% above 700 mg/dL Intralipid) in native lipemic samples, and in two serum aliquots cleared of lipemia on Beckman Coulter AU400 analyzer. The results were compared using Bland & Altman plot. Interference of triglycerides on bias was checked by linear regression. All results were analyzed using MedCalc 9.4.2.0 statistical software (MedCalc Software bvba, Mariakerke, Belgium). Results: Bland & Altman plot revealed statistically significant bias between the two compared procedures measured in lipemic samples (differences (%): -36.35, 95% CI = -50.5834 to -22.1214) and aliquots cleared by high speed centrifugation (differences (%): -22.1744, 95% CI = -33.7913 to -10.5575). However, there was no statistically or clinically significant bias between the lipase activity measured in aliquots cleared by serum delipidation (differences (%):-4.1871, 95% CI = -9.7848 to 1.4107) nor it was affected by varying triglyceride levels (R2 = 0.03692, P=0.276). Conclusions: Serum lipase activity can be accurately measured using Beckman Coulter colorimetric method in grossly lipemic plasma samples cleared of lipemia by serum delipidation.