Diagnostic value of amylase and lipase in diagnosis of acute pancreatitis

Abstract

One of the causes of acute abdomen is acute pancreatitis. Usually when there is an increase in pancreatic enzymes including amylase and lipase levels three times higher than normal, the diagnosis of pancreatitis is made. Our study focused on the diagnostic value of amylase and lipase in the diagnosis of acute pancreatitis with sensitivity, specificity, positive predictive value and negative predictive value. This study is a descriptive-analytical study examined 458 patients with acute abdomen who were referred to emergency department of Imam Reza Hospital of Tabriz. Information compiled a checklist and analysis software has been SPSS 15. The results show that among 458 studied patients, 189 (41.3%) was men and 269 patients (58.7%) were women. 88 (19.2%) patients had diagnosis of acute pancreatitis. In patients with acute pancreatitis, amylase average was 397.17 IU/L. Among patients with acute pancreatitis, blood amylase of 22.7 % were d' 110 IU/L, 35/2% were in the 330-110 IU/L and 42% were e'330 IU/L. Diagnostic accuracy of amylase for cutoff 110 IU/L was as follows: sensitivity= 79.2%, negative predictive value (NPV)= 92% (suitable), positive predictive value (PPV) = 43%, specificity= 69% (not suitable and could not help to diagnose). Diagnosis accuracy of amylase for cutoff in 330 IU/ L was as follows: specificity= 92%, NPV= 84% (suitable for diagnosis), sensitivity= 42%, PPV= 61%, (not suitable and could not help to diagnose). Study shows average lipase level in patients with acute pancreatitis was 399 IU/L. Among 19.3% of patients with acute pancreatitis, the blood lipase was d'80, 22.7 % were in 240-280 IU/L, and 58% was upper than 240 IU/L. Diagnostic value of lipase, for cut off 80 IU/L was as follows: sensitivity=80%, NPV= 92% (suitable for diagnosis), but specificity= 69% and PPV= 44% which were not suitable for diagnosis. For cut off In 240 IU/L specificity= 88%, NPV= 87% (suitable for diagnosis) but sensitivity= 57% and PPV= 58% not suitable and could not help to diagnose. Our study showed that levels of lipase and amylase enzymes are helpful for diagnosis of acute pancreatitis. Different diagnostic thresholds for each enzyme assay have different sensitivity and specificity. Therefore, that by increasing the level of diagnostic threshold, specificity of tests increases but there sensitivity decrease. In our study, the diagnostic threshold of the negative predictive value was acceptable but the positive predictive value was unacceptable.