CLINICAL EVALUATION OF SERUM PANCREATIC SECRETORY TRYPSIN INHIBITOR (PSTI) DETERMINED BY RADIOIMMUNOASSAY

Abstract

A clinical significance of serum PSTI determination was studied in 122 healthy controls aged 20 to 93 years and in 157 patients with various diseases, including 59 cases with pancreatic diseases confirmed clinically or surgically. Serum PSTI was determined by the radioimmunoassay kit (Shionogi Pharmaceutical Co., Japan) and was compared with serum amylase, immunoreactive elastase-1 (IRE) and immunoreactive trypsin (IRT). Furthermore, serum PSTI was compared with the results of pancreozymin-secretin (PS) test in 73 cases who were clinically suggested to have pancreatic disorders.
1) The radioimmunoassay for PSTI was highly sensitive, specific and reproducible. 2) Serum PSTI significantly increased with age in healthy controls. Clinical reference range of serum PSTI determined by Hoffmann's method was 12.16±5.32ng/ml (mean±2SD). 3) Serum PSTI increased together with serum amylase, IRE and IRT in 20 cases after endoscopic retrograde pancreatography. 4) In acute pancreatitis, serum PSTI was considerably elevated and maintained high level more longer than serum pancreatic enzymes. 5) Abnormal high level was more frequently seen in serum PSTI than in serum amylase in chronic pancreatitis or pancreatic cancer, especially in head cancer. 6) Abnormality of serum PSTI was also found in patients with renal failure and in some patients with liver cirrhosis or diabetes mellitus. 7) Serum PSTI significantly increased in subjects disturbed one or two secretory parameters of PS test, and also increased in those without apparent abnormality of the test. However, it did not increased in any subjects disturbed three secretory parameters of PS test.
These findings indicate that serum PSTI reflects exactly pathophysiological changes in the pancreas in comparison with serum amylase and that the determination of serum PSTI is useful for the diagnosis of pancreatic diseases.