Failure of inhibitor assay to determine isoamylase distribution

Isoamylase distribution in the urine of normal individuals and patients admitted to the hospital with hyperamylasemia was determined by a wheat inhibitor mmethod and compared to results obtained by cellulose-acetate electrophoresis. We report two cases where the inhibitor ethod failed to give accurate results in urine, as well as serum, when compared to both electrophoresis and column chromatography. The discrepant results were due to the unexpected inhibition of P isoamylase.