Diagnosing acute pancreatitis-Clinical and radiological characterisation of patients without threefold increase of serum lipase.

OBJECTIVES: Diagnosing acute pancreatitis (AP) may be challenging in patients with acute abdominal pain but missing threefold increased serum lipase levels (Lip-). This studyaims both to characterize these patients using clinical, radiological and mortality data, and to assess the group of patients who need contrast-enhanced computed tomography (CECT). METHODS: In this retrospective, IRB approved study 234 consecutive patients with AP were investigated. Inclusion criteria were single (SAP) and recurrent attacks (RAP) of AP and CECT ≥72h after onset of symptoms. Severity of AP was assessed by C-reactive protein at 48h after hospital admission and using 3 CT-based scores (CTSI, mCTSI, EPIC) by 2 observers. Mortality rates from pancreatic and non-pancreatic causes were noted with regard to lipase increase. Results were compared with paired t-test and Wilcoxon signed-rank test. RESULTS: 64/234 (27%) patients belonged to Lip- group and 170/234 (73%) patients were allocated to Lip+ group. Significantly more male patients (78% in Lip- vs. 63% in Lip+, p<0.05) with RAP (63% in Lip- vs. 21% in Lip+, p<0.001) were observed in the Lip- group. EPIC was significantly lower in Lip- group compared to Lip+ group (3(IQR 2-5) vs. 2(IQR 1-3), p<0.001). Mortality from pancreatic and non-pancreatic causes was comparable in Lip- and Lip+ group (pancreatic causes: 9% vs. 6%, p=0.60; nonpancreatic causes: 8% vs. 5%, p=0.58). CONCLUSIONS: 27% of all patients with AP presented without threefold increase of lipase levels. Thus, they would be underdiagnosed without confirming CECT, which revealed significantly lower counts of pleural effusions and ascites. Male patients with RAP were found significantly more often among the Lip- group. Hence, they would benefit the most from CECT for diagnosing AP.