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Macroamylase: prevalence, distribution of age, sex, amylase activity, and electrophoretic mobility
Abstract:
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.
Insights
Macroamylase, an enzyme complex, was found in 9.6% of patients with elevated serum amylase. This finding helps clarify hyperamylasemia of unknown origin and its electrophoretic patterns.
Area of Science:
- Clinical Chemistry
- Biochemistry
- Enzymology
Background:
- Hyperamylasemia of unknown origin presents a diagnostic challenge.
- Macroamylase, a complex of amylase with immunoglobulins, can cause persistent hyperamylasemia.
- Quantifying macroamylase prevalence and characterizing its electrophoretic patterns are crucial for diagnosis.
Purpose of the Study:
- To quantitate the contribution of macroamylase to hyperamylasemia of unknown origin.
- To identify the age and sex distribution of patients with macroamylase.
- To characterize the electrophoretic patterns of macroamylase.
Main Methods:
- Analysis of serum amylase isoenzymes in 2,900 patients with elevated serum amylase over three years.
- Electrophoretic isoenzyme analysis to identify and characterize macroamylase.
- Comparison of demographic data between macroamylase-positive and macroamylase-negative groups.
Main Results:
- Macroamylase was identified in 9.6% of patients with hyperamylasemia.
- Serum amylase activity in macroamylase cases ranged from 1 to 20 times the normal level.
- No significant differences in age or sex distribution were observed between macroamylase-positive and negative groups.
- Electrophoretic patterns showed atypical anodal bands in 60% of cases, bands between pancreatic and salivary amylase in 30%, and bands faster than pancreatic amylase in 10%.
Conclusions:
- Macroamylase is a significant contributor to hyperamylasemia of unknown origin.
- Macroamylase occurs across all age and sex demographics without specific predisposition.
- Distinct electrophoretic patterns are characteristic of macroamylase, aiding in its identification.