LONGITUDINAL EVALUATION OF SERUM TRYPSINOGEN MEASUREMENT IN PANCREATIC-INSUFFICIENT AND PANCREATIC-SUFFICIENT PATIENTS WITH CYSTIC-FIBROSIS

We studied serial measurements of serum cationic trypsinogen in patien ts with cystic fibrosis to assess the predictability of changes in ind ividuals and the value of longitudinal measurement in defining pancrea tic status, Three hundred twenty-nine patients with cystic fibrosis, a ged 3 days to 40 years, had serum levels of trypsinogen measured on 2 to 12 occasions for periods ranging from 1 week to 7 years, Patients w ere classified into three groups on the basis of 72-hour fecal fat stu dies performed at the time of diagnosis, Two hundred thirty-three pati ents had pancreatic insufficiency (Pi), 78 had pancreatic sufficiency (PS), and 18 had PS at diagnosis but acquired PI during follow-up (PS --> PI). Infants with PI had greatly elevated serum trypsinogen levels that fell sharply in the first years of life, so that by age 7 years more than 95% had subnormal values; individual patient values followed a predictable course similar to previously reported cross-sectional a ge-related values, In patients with PS, serum trypsinogen levels gener ally remained within or above the normal range and, after age 10 years , were well above the upper limit for Pi patients. Within-patient vari ance was significantly greater (p < 0.0001) in patients with PS than i n those with PI who were older than 7 years of age, Changes in patient s within PS --> PI generally followed the pattern seen in patients wit h PI, but values in older patients tended to be in the higher range, W e conclude that serial measurement of serum trypsinogen is a valuable tool for monitoring the pancreatic status of patients with cystic fibr osis and PS.