P3 amylase isoenzyme in the diagnosis of pancreatitis.

P3 amylase isoenzyme was found to be present in the plasma of 43 out of 140 patients with suspected pancreatitis. Of 43 patients with the P3 isoenzyme, pancreatitis was definitely confirmed in 21 by laparotomy. Of the remainder, 19 had probable pancreatitis based on a combination of clinical, biochemical, endoscopic (ERCP), ultrasonic and computerised tomographic evidence, while 3 had possible pancreatitis based on clinical evidence alone. Of 97 patients without the P3 isoenzyme 1 patient had evidence of probable pancreatitis and 1 had evidence of possible pancreatitis. Statistical analysis (excluding the 4 cases of possible pancreatitis) showed that the P3 amylase isoenzyme had a sensitivity of 98%, a specificity of 100% and an efficiency of 99%. The predictive values of a positive and negative test were 100% and 99% respectively. Hyperamylasemia was not a pre-requisite to the presence of the P3 isoenzyme, since 11 out of 13 patients, with normal total amylase levels, were found to have the P3 band and confirmation of their pancreatitis. It is concluded that the P3 amylase isoenzyme is a specific and sensitive test for pancreatitis, and appears also to be superior to the total plasma amylase.