Measurement of α-glucosidase activity in serum from patients with cystic fibrosis and pancreatitis

We measured the activity of a non-lysosomal α-glucosidase with pH optimum near 6.0 in serum from a wide variety of patients, using the fluorogenic substrate, 4-methylumbelliferyl-α-D-glucopyranoside. Acutely ill patients with cystic fibrosis (CF) demonstrated significant increases in α-glucosidase compared with CF outpatients. The former group of CF patients experienced far more severe chronic pulmonary disease than did the latter, whereas both groups had similar degrees of gastrointestinal impairment. Patients with pancreatitis associated with trauma or complicated by severe necrosis, hemorrhage, or abcess also displayed greater increases in α-glucosidase than did patients with uncomplicated (edematous) pancreatitis. For CF outpatients and patients with either edematous pancreatitis or pancreatic cancer, the α-glucosidase activity was similar to that for the general hospital-patient population. Corresponding changes were not observed for other measured serum glycosidases (α-fucosidase, α-mannosidase, β-glucuronidase, β-N-acetylglucosaminidase). Measurement of serum α-glucosidase may be of value in assessing the clinical course of CF and in differentiating necrotizing from edematous pancreatitis.