Immunoreactive trypsinogen levels in infants with cystic fibrosis complicated by meconium ileus

Abstract

To examine abnormalities in immunoreactive trypsinogen (IRT) in infants with cystic fibrosis (CF) and meconium ileus (MI) and to evaluate the utility of IRT as a diagnostic aid in MI, we compared IRT in 19 infants with CF and MI to values in normal infants and in 91 infants with CF without MI. Infants with CF without MI were identified between 1982–1989 through a statewide screening program based on IRT measurements ( n=83) or through clinical presentation ( n = 8). Infants with MI were identified through clinical presentation during the same period. The IRT level of MI patients as a group (195±23 ng/ml) was greater than the cutoff value for IRT in normal infants (140 ng/ml, corresponding to the 99.7th percentile for infants less than 20 days of age; P<0.05). However, eight of 19 infants with meconium ileus (42%) had IRT levels below the cutoff. IRT in infants with MI was significantly lower than in infants with CF without MI (288 ± 10 ng/ml; P < 0.001). The relatively low IRT value in MI patients did not correlate with any of the clinical parameters we examined, including homozygosity for the delta F508 mutation. We conclude that although IRT may be elevated in patients with MI, it is not reliable as a diagnostic aid since values frequently fall within the normal range. In addition, the lower level of IRT in infants with MI compared to other infants with CF without MI suggests a difference between the two groups in expression of pancreatic injury.