Serum amylase and lipase levels in healthy volunteers assessed by multiple commercial analyzers: Variability with established reference values

Background/Aims: Although serum pancreatic enzyme measurements for amylase and lipase are the most widely used biochemical tests for the diagnosis of pancreatitis, limitations for their interpretation of pancreatic disease do exist. An international reference method or an evidence-based cut-off value of serum pancreatic enzyme levels has not been established to facilitate standardization. Therefore, different analytic methods for serum pancreatic enzyme levels have verified their own Reference Ranges (RR) as normal values. The aim of this study is to evaluate the frequency of serum pancreatic enzyme values outside of the RR in healthy volunteers, using 5 different pancreatic enzyme analyzers to determine variability of values between analyzers. Methods: Healthy volunteers were screened to exclude a history of pancreatic disease or pancreatic surgery, severe gastrointestinal disease, excess alcohol intake, tobacco use, amongst other conditions. Volunteers were prospectively enrolled and blood samples from a single draw were analyzed for serum pancreatic enzyme levels on five different automated chemistry analyzer platforms. Whether or not the results were within each analyzer's institutional RR was evaluated. Results: Among screened healthy volunteers, 180 participants were enrolled who met the inclusion criteria. Serum amylase results were outside the RR in 8 (4.4%), 11 (7.2%), 19 (10.5%), 6 (3.3%) and 7 (3.9%) subjects, respectively, based on the 5 separate analyzers. Serum lipase results were not within the RR in 3 (1.7%), 20 (13.2%), 13 (7.2%), 1 (0.6%) and 2 (1.1%) subjects, respectively. Among all 22 (12.2%) subjects that were outliers of the serum amylase level, 10 (5.6%) of those subjects were outside of the RR for two or more analyzers. In contrast, among all 32 (17.8%) subjects who were outliers of serum lipase level, only four subjects (2.2%) were outside of the RR for two or more analyzers. Conclusion: Although there was slight variability in test results for serum amylase and lipase between different commonly available testing systems in healthy subjects, no values exceeded three times the upper limit of normal. There was a small group of healthy volunteers that fell outside of the reference range on two or more analyzers. If there is clinical ambiguity due to an abnormal serum pancreatic enzyme, further diagnostic testing can be pursued. Standardization amongst pancreas enzyme analyzers with a unified reference methodology and standard would be beneficial.