[Value of isoamylases in the diagnosis of exocrine pancreatic insufficiency in childhood].

Pancreatic- (P) and salivary-like (S) isoenzyme concentrations were measured in 64 healthy children and 44 patients with cystic fibrosis (CF) the most frequent cause of exocrine pancreatic insufficiency in childhood. The isoamylases were determined by means of an established method, the isoelectric focusing (IEF) and by a recently described inhibitory test, the Phadebas-Isoamylase test (PIT). Serum isoamylase levels were age dependent during the first 16 months of life. In healthy infants as well as in patients with CF up to 16 months of age P type amylase concentrations were very low and of no diagnostic value whereas S type amylase was 4-fold increased in the CF-group. CF-patients older than 1 year and 4 months showed pathologically diminished P type amylase levels in 86% (IEF) or 70% (PIT) resp. Further investigations as well as clinical findings revealed a normal pancreatic function in 5 patients (= 14%) with normal P type concentrations in both tests. Thus an exocrine pancreatic insufficiency could be diagnosed by means of lowered P type amylase in all (IEF) resp. 81% (PIT) of our patients. The specificity of the tests with regard to P type amylase amounted to 1 for IEF and 0.98 for PIT.