Associations of abnormal blood lipid levels with hospitalization cost and disease severity in patients with hyperlipidemic pancreatitis: a retrospective cohort study.

Do not diagnose acute pancreatitis (AP) from an elevated lipase alone. ACG establishes the diagnosis by identification of 2 of the 3 following criteria: (i) abdominal pain consistent with the disease, (ii) serum amylase and/or lipase greater than 3 times the upper limit of normal, and/or (iii) characteristic findings on abdominal imaging. Serum lipase is the preferred enzyme; serum amylase alone cannot be used reliably because of limitations in sensitivity and negative predictive value. The guideline states explicitly that some patients without AP will have elevated amylase and/or lipase, sometimes greater than 3 times normal, and that in the absence of abdominal pain consistent with the disease, elevations of amylase and lipase do not predict the development of AP. The 3 times threshold is qualified, not absolute: although most studies show diagnostic efficacy at greater than 3 to 5 times the upper limit of normal, a cutoff greater than 3 to 5 times may be needed especially in some patient groups such as diabetic patients, a Japanese consensus conference could not reach consensus on appropriate upper limits of normal, and clinicians must consider the clinical condition of the patient when evaluating amylase and lipase elevations. Pain quality is a stated discriminator: AP pain is typically epigastric or left upper quadrant, usually constant with radiation to the back, chest, or flanks, though this description is nonspecific and intensity is variable; pain described as dull, colicky, or located in the lower abdominal region is not consistent with AP and suggests an alternative etiology. Intensity and location of pain do not correlate with severity. When doubt about the diagnosis of AP exists, abdominal imaging may assist, and contrast-enhanced CT provides more than 90 percent sensitivity and specificity; however the guideline's Diagnosis key concept is that early or at-admission routine CT should NOT be performed to determine severity and should be reserved for patients in whom the diagnosis is unclear or who fail to improve clinically within the first 48 to 72 hours after hospital admission and intravenous hydration. Lipase is also found to be elevated in a variety of nonpancreatic diseases; the specific non-pancreatitis causes the document enumerates (given for amylase) are macroamylasemia, decreased glomerular filtration rate, diseases of the salivary glands, and extrapancreatic abdominal diseases associated with inflammation including acute appendicitis, cholecystitis, intestinal obstruction or ischemia, peptic ulcer, and gynecological diseases. Once the diagnosis of AP is established there is no reason to follow serum amylase or lipase, because there is no relationship to severity, prognosis, or the decision to refeed or discharge the patient. Separately, as an etiology key concept, in patients older than 40 years in whom an etiology is not established, a pancreatic tumor should be considered as a possible cause of AP.