We compare the clinical value of assay of
amylase (EC 3.2.1.1)
isoenzymes with that of
lipase (EC 3.1.1.3) in serum from patients with proven
acute pancreatitis or with
hyperamylasemia from other causes. In the former group we measured
amylase,
lipase, and isoamylases daily.
Lipase and P(pancreas)-type isoamylases reached the highest mean values on the first day of an attack of
acute pancreatitis (day one).
Lipase declined rapidly, and by day four its mean activity was about the same as that of
amylase and lower than that of the P-type isoamylases. Great inter-individual variations were found among patients with a similar
clinical course. Of the 85 samples analyzed,
amylase activity for 36 declined to within reference limits, but 18 of the 36 had high
lipase activity, 18 had high P-type isoamylases activity, and 31 had P3
isoenzyme, which is not detectable in normal sera. Determination of isoamylases is a more sensitive index to
acute pancreatitis than
lipase assay and may be particularly useful when
pancreatitis is suspected despite a normal total
amylase activity. In the group of patients with
hyperamylasemia from other origins, three had
macroamylasemia, one had
mumps, one had abdominal
trauma without pancreatic injury, and one had
pelvic inflammatory disease. The specific pattern of
macroamylase on electrophoresis permitted a precise diagnosis of
macroamylasemia; normal
lipase had only ruled out
pancreatitis. In the three other cases,
lipase and isoamylases excluded pancreatic involvement.