Thanks to all who provided feedback on our case of a 35 year old male with left sided abdo-pain, elevated lipase, normal pancreatic amylase and normal imaging studies.
Several hypotheses emerge:
(1) That the lipase elevation is a false positive. It has been reported that this can occur in inflammatory bowel disease and cholangitis. Some papers mention false-positive lipase (Scand J Gastroenterol 1987 22(6): 719-24).
(2) That this represents alcoholic pancreatitis (as opposed to other aetiologies). Some papers have described normoamylasaemia as a feature of alcoholic acute pancreatitis (Ann Surg 1990 212(5): 648-9) and others have shown elevated lipase to amylase ratios as evidence for an alcoholic aetiology of acute pancreatitis (Am J Gastroenterol 1992 87(12): 1755-8). Other papers have refuted this view (Dig Dis Sci 1993 38(7): 1265-9 and Z Gastroentreol 1994 32(1): 8-11). The deranged LFTs might favour this hypothesis in the present case and will be explored further.
(3) Acute pancreatitis secondary to hypertriglyceridaemia sometimes presents with spuriously normal amylase levels. This has been reported at much higher triglyceride levels than those seen in the present case. Our pancreatic amylase method-sheet claims that lipaemia only potentially causes interference at triglyceride levels above approximately 35 mmol/l.
(4) The lipase elevation could be secondary to an abnormal form of the lipase enzyme or "macro-lipase" similar to macro-amylase and others, although I have not seen this described in the literature.
I have presented these views to our surgical colleagues and suggested follow-up samples for lipase and pancreatic amylase.
Dr Chris Florkowski
Chemical Pathologist
Christchurch, New Zealand
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