The contribution made by
macroamylase to the occurrence of
hyperamylasemia of unknown origin has not been previously quantitated nor has the distribution of age and sex been identified in a large sample. Knowing the pattern of this
enzyme complex when analyzed by an electrophoretic
isoenzyme procedure would be of importance in recognizing its presence. During a three-year period we have studied a population of 2 900 patients with elevated serum
amylase from whom specimens were sent to our laboratory with a request for
amylase isoenzyme analysis. It was assumed that the primary reason for requesting these analyses was to clarify the presentation of
hyperamylasemia.
Macroamylase occurred in 9.6% of these patients. The total activity of the
macroamylase specimens was typically 1 to 4 times normal but ranged to 20 times normal. Comparing these patients with a
macroamylase-negative group, the distribution of age and sex was found to be no different.
Macroamylase had a characteristically unusual electrophoretic pattern with bands faster than normal pancreatic
amylase in 10% of cases, bands between pancreatic and salivary in 30% of cases, and the remaining 60% with atypical anodal bands.