Value of pancreatic-type isoamylase assay as an index of pancreatic insufficiency.

The study here reported was undertaken to assess the value of assay of the specific isoamylase form arising from the pancreas (P-type) as an index of pancreatic exocrine insufficiency. Measurements were made of serum total amylase activity, serum P-type isoamylase activity, and the amount of P-type isoamylase relative to creatinine (Upam/Ucr) in the urine in a series of patients with clinically suspected chronic pancreatitis and pancreatic insufficiency as determined from the pancreatic secretory response to secretin stimulation. Abnormally low values for P-type isoamylase in the serum and urine of these patients were infrequent. Conversely, values within the normal ranges for serum P-type isoamylase and Upam/Ucr were common. It is concluded that while subnormal values for P-type isoamylase in the serum and urine may be viewed as supportive evidence for pancreatic insufficiency, failure to find such values does not exclude this condition.