Investigations

Investigations should be geared towards diagnosis and prediction of severity.

Thus, immediate assessment should aim for diagnosis of pancreatitis and discovery of any cardiovascular, respiratory or renal compromise. This would include:

1) Urinalysis and pregnancy test in any female of child-bearing age

2) Standard FBC, U&E, LTFs, glucose, CRP

Pancreatic insufficiency may lead to a lack of insulin and subsequent hyperglycaemia and alkaline phosphatase, in particular, may be raised if gall stone obstruction is the cause.

Sometimes used as an early indicator of severity and to monitor progression of inflammation.

• CRP >200 units/L indicates a high risk of developing pancreatic necrosis.
  • However, there is ongoing doubt over the diagnostic test accuracy of CRP for predicting pancreatic necrosis. It may take 72 hours after symptom onset to become accurate as an inflammatory marker.

3) Serum calcium

Sequestration of calcium in fat may lead to hypocalcaemia.

4) Serum pancreatic enzymes

Amylase is the most widely used marker of pancreatitis, yet it can be raised in other causes of acute abdominal pain. A normal amylase does not rule out pancreatitis as it can take 24-48 hours to peak, and the degree of elevation of amylase does not equate to severity of disease. Sensitivity is around 80-90% although specificity is as low as 40%. [5,6]

lipase levels remain elevated for longer (up to 14 days after symptom onset vs. 5 days for amylase), providing a higher likelihood of picking up the diagnosis in patients with a delayed presentation.

Although not available at all centres, estimation of plasma lipase shows a slightly superior sensitivity (90%) and specificity (90%) and overall greater accuracy than amylase as it is only produced by the pancreas and has a longer half-life. [5,6]

5) Arterial blood gases

Hypoxia or acidosis may suggest systemic effects.

6) ECG

7) Chest x-ray

Additional tests to determine the aetiology of pancreatitis can be carried out later, e.g. lipid profile, auto-immune antibodies and viral titres.

Further tests for admitted patients are:

• Abdominal ultrasound
• CECT
• MRCP
• EUS

Emerging tests

Urinary trypsinogen-2 (>50 nanograms/mL) shows promise as a diagnostic test.

• Elevated urinary trypsinogen-2 (>50 nanograms/mL) seems to be at least as sensitive and specific as serum lipase and amylase (both at the standard threshold of 3 times the upper limit of normal) for the diagnosis of acute pancreatitis.
  • Urinary trypsinogen-2 is a rapid and non-invasive bedside test but is not yet widely available for clinical use.
  • A meta-analysis reported a pooled sensitivity of 82% and specificity of 94% for diagnosing acute pancreatitis.

Interleukin-6, interleukin-8, and interleukin-10 may be predictive markers for the development of severe acute pancreatitis.

• One study reported a sensitivity of 81% to 88% and specificity of 75% to 85% for IL-6 and a sensitivity of 65% to 70% and specificity of 69% to 91% for IL-8 for prediction of severe acute pancreatitis.

Learning Bite

Serum lipase is more sensitive and specific than amylase in the diagnosis of pancreatitis, although neither can rule it out.