Serum immunoreactive trypsin in type IV hyperlipoproteinemia.

Serum immunoreactive trypsin (IRT) under basal conditions and after pancreatic stimulation with secretin was studied in 10 patients with type IV hyperlipoproteinemia (HLP) and in 10 control subjects. No significant difference was observed between basal values of the two groups (p = NS). The increase of serum IRT was already significant 5 minutes after secretin administration (p < 0.01) and persisted with significance for one hour in both groups. The integrated trypsin output (ITO) was significantly greater in type IV HLP than in controls (510.3 +/- 17.8 and 72.2 +/ 17.6 respectively, mean +/- SEM, p < 0.0125). Only 2 (20%) of 10 patients with HLP had an ITO in the range of the controls. No significant correlation was found between ITO and triglyceride levels (p = NS). The response of serum IRT to secretin in HLP patients appears comparable to that observed in alcoholics and in patients with chronic pancreatitis with mild to moderate exocrine dysfunction, in whom there may be an abnormal regurgitation of trypsin-like material into the blood stream after secretin stimulation, probably due to an obstruction to pancreatic secretory flow. A similar obstructive mechanism may be hypothesized also in patients with HLP, but no data concerning the exocrine pancreatic secretion and the histological features of the pancreas are available to confirm this hypothesis.