Establishing the blood reference interval of pancreatic elastase‐1: A prospective study

Background and Aim Pancreatic elastase‐1 (PE‐1) has been investigated in pancreatic disorders. However, the reference interval (RI) of PE‐1 in blood remains unconfirmed. We aimed to establish the blood RI of PE‐1 in an adult population. Methods In this prospective cross‐sectional study, we enrolled 400 adults who had received the whole‐body physical check‐up program between May 1, 2019 and November 20, 2019. The serum and plasma PE‐1 levels were measured by latex turbidimetric immunoassay in different storage conditions (fresh, refrigerated, and frozen). The 95% and 99% RI of PE‐1 were calculated according to the Clinical & Laboratory Standards Institute guidelines. The correlations between PE‐1 and other parameters were analyzed using multivariable regression models. Ultimately, 38 patients with acute pancreatitis were prospectively recruited as the validation cohort. Results The PE‐1 levels in fresh serum were highly correlated with those in refrigerated (R2 = 0.998) or frozen (R2 = 0.942) samples; however, plasma should not be suggested in frozen conditions (plasma vs serum: R2 = 0.185). In the RI study population (202 male & 198 female participants), the median age was 52.6 (25–75% interquartile range: 43.1–61.0). The 95% and 99% RIs of PE‐1 were 30.0–221.0 and 22.0–359.0 ng/dL, respectively. Triglycerides (β = 0.106, P = 0.033), lipase (β = 0.154, P = 0.007), and CA19–9 (β = 0.130, P = 0.008) were independent factors associated with PE‐1. In the pancreatitis validation cohort, with a cut‐off value of 359.0 ng/dL, the sensitivity and specificity were 100% and 99.8%, respectively. Conclusion The RI of PE‐1 established in this study can be used for further applications. Serum is the suggested form for frozen sample storage.