Serum Biochemical Markers of Acute Pancreatitis

Acute pancreatitis usually occurs as a result of alcohol abuse or bile duct obstruction. A careful review of the patient's history and appropriate laboratory studies can help the physician identify the etiology of the condition and guide management. Prompt identification of patients who need intensive care referral or subspecialty consultation is crucial. 

The number of serum biomarkers used to detect and assess severity and prognosis of acute pancreatitis (AP) is substantial. 

In recent years urinary trypsinogen-2, trypsinogen activation peptide, procalcitonin, interleukin 6, C-reactive protein (CRP), phospholipase A(2), serum amyloid A, have been suggested as replacements for amylase and lipase; even ALT and bilirubin have been used to suggest a gallstone as the cause. 

Serum amylase remains the most commonly used biochemical marker for the diagnosis of acute pancreatitis, but its sensitivity can be reduced by late presentation, hypertriglyceridaemia, and chronic alcoholism. The advantages of amylase are its technical simplicity, availability and high sensitivity. Its greatest disadvantage is its low specificity. A normal amylase would usually exclude the diagnosis of AP, with the exception of AP secondary to hyperlipidemia, acute exacerbation of chronic pancreatitis, and when the estimation of amylase is delayed in the course of the disease. 

The major advantage of lipase is an increased sensitivity in acute alcoholic pancreatitis and in patients who initially present to the emergency room days after the onset of the disease, as lipase remains elevated longer than amylase. 

Simultaneous estimation of amylase and lipase does not improve the accuracy. A recent survey from several laboratories when both amylase and lipase were ordered tends to confirm this – when one is normal the other is most often normal and when one is abnormal so is the other. 

Some clinicians feel that serum lipase is a more reliable diagnostic marker of AP than serum amylase; others argue that urinary trypsinogen-2 is convenient, of comparable diagnostic accuracy and provides greater (99%) negative predictive value; others suggest that the serum trypsin level is the most accurate laboratory indicator for AP and still others feel that C-reactive protein (CRP) remains the most useful. To some CRP is still the reference parameter of all predictors indicating severe disease and pancreatic necrosis. 

While most parameters peak early and decrease rapidly thereafter, C-reactive protein (CRP), phospholipase A(2), procalcitonin and serum amyloid A are reliable predictors with persistently elevated levels in severe disease. So far, no single parameter has been developed which is suitable for early prediction of infected pancreatic necrosis. 

It seems that there is not yet a consensus on which marker(s) to use. My conversations with those in the field suggest that both amylase and lipase in tandem is the most common approach. The data do not suggest that this is the best approach. 

by  David Plaut