Pancreatic insufficiency in infants with cystic fibrosis

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In this issue of The Journal, Sontag et al report the time course and physiologic significance of decline in serum immunoreactive trypsinogen levels in infants (n = 317) with cystic fibrosis. The presence or absence of pancreatic disease was determined based on genotype and fat malabsorption studies and statistical models to describe IRT decline were developed. Infants with “severe disease” exhibited a progressive decline in IRT with nondetectable levels usually by age 5. By contrast, “mildly affected” infants showed a decline in the first 2 years and then leveled off at a concentration greater than published norms. There was an inverse correlation between IRT and fecal fat. IRT values were lower in infants with meconium ileus compared to infants screened at birth, suggesting that there might be increased pancreatic injury in infants with meconium ileus. There was also a suggestion that IRT is heritable among patients with severe disease, which indicates the potential role of gene modifiers in early pancreatic disease in cystic fibrosis.

A therapeutic study of pancreatic insufficiency in cystic fibrosis is also published in this issue. Borowitz and a multi-center group studied a novel pancreatic enzyme product (Thera CLEC) containing synthetic, microbially-derived lipase, protease, and amylase. Subjects with cystic fibrosis and pancreatic insufficiency (n = 117) were studied on and off pancreatic enzyme replacement. They were randomized to treatment with the new synthetic enzyme in three different groups: a low, mid and high group. After 14 days of therapy, coefficient of fat absorption was measured again and was significantly greater than placebo in the mid- and high-dose groups. Coefficient of nitrogen absorption was also measured and was similar to coefficient of fat absorption. The greatest improvement was seen in patients with the lowest coefficients of absorption. These results suggest that the new microbially-derived pancreatic enzyme replacement product is effective at a mid-dose of 25,000 units of lipase, 25,000 units of protease, and 3,750 units of amylase per capsule.