Pancreatic function testing in meconium disease in CF: two case reports.

We report two infants with cystic fibrosis (CF), presenting with meconium ileus and meconium plug, who had no clinical or biochemical evidence of pancreatic insufficiency during infancy. They underwent pancreatic secretory function testing at 11 and 9 months of age, respectively. Both patients had sufficient lipase and colipase secretion to maintain normal digestion of fat, confirming that meconium disease in CF does not necessarily imply pancreatic insufficiency and the need for enzyme supplementation in infancy. Nonetheless, we documented markedly reduced enzyme secretion in both patients, implying a potential role for the pancreas in the pathogenesis of meconium disease, even when clinical pancreatic insufficiency is absent. In addition, our patient with meconium ileus had a severely limited fluid secretory capacity (10.3% of mean normal values). In contrast, the patient with the milder presentation of meconium plug had a far greater ability to secrete fluid (75% of mean normal), but had poorer pancreatic proteolytic activity. We suggest that impaired fluid secretion may be a very significant factor in the pathogenesis of meconium ileus, and we speculate that an inability to maintain sufficient intraluminal fluid relative to the degree of pancreatic proteolytic deficiency may more adequately explain the risk of occurrence and the severity of intestinal obstruction in CF than either factor alone.