How is acute pancreatitis diagnosed biochemically and radiologically?

Diagnosis is by a serum amylase more than 3 times the upper limit of normal (or over 1000 IU), or a raised serum lipase (more specific). Contrast-enhanced CT is used when the diagnosis is in doubt, the presentation is delayed, or to assess severity and complications.

Clinical relevance. Knowing the enzyme thresholds and the role of CT enables accurate diagnosis and severity assessment.

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Diagnosis of acute pancreatitis

The diagnosis combines clinical features with enzyme elevation and, when needed, imaging.

Biochemical

• Serum amylase more than 3 times the upper limit of normal (or over 1000 IU).
• Serum lipase: more sensitive and specific, and stays elevated longer.
• Amylase may be normal if presentation is late or in acute-on-chronic disease.

Radiological

• Contrast-enhanced CT where the diagnosis is in doubt or presentation is delayed; it assesses necrosis (non-enhancing areas), fluid collections, and complications.
• Ultrasound of the biliary tree (within 24 hours) to look for gallstones as the cause.