The BT-PABA/PAS test in tropical diabetes

A 'screening' test is needed to identify patients with chronic pancreatitis among diabetics in tropical field surveys. We have examined the potential diagnostic yield of the BT-PABA/PAS test of exocrine pancreatic function in this setting. The recoveries of both PABA and PAS in eight healthy controls from Madras, south India, were lower than in controls from Manchester, north west England (mean +/- S.D., 51 +/- 11 vs. 79 +/- 7%, P < 0.001 for PABA; 52 +/- 11% vs. 81 +/- 7%, P < 0.001 for PAS) but the % PABA/PAS excretion index (PEI) was similar (0.96 +/- 0.14 vs. 0.96 +/- 0.06). Using a cut-off value of 0.75 for the PEI in a study group including eight patients with chronic pancreatitis and 26 with primary forms of diabetes, test sensitivity was 75%, specificity 92%, positive predictive value 75%, negative predictive value 92% and efficiency 88%.

Exocrine pancreatic function after gastrectomy. Specificity of indirect tests

We compared intraindividually the specificity of indirect pancreatic function tests before and after total (n = 4; Roux-en-Y) or subtotal (n = 6; Billroth II) gastrectomy. Before gastrectomy only 1 patient showed a falsely pathological result with the pancreolauryl test (90% specificity), while the results of all the other tests were correctly normal (100% specificity using the usual cutoff limits). After gastrectomy the respective specificities were as follows: pancreolauryl test 10%, bentiromide test 70%, fecal chymotrypsin 70%, and plasma amino acid consumption test 100%. There was no obvious difference in the reduction of specificity between subtotal and total gastrectomy. The respective preoperative to postoperative changes in the median test data were as follows: plasma amino acid consumption test +21%, bentiromide test -12%, fecal chymotrypsin -51%, and pancreolauryl test -53%. It is concluded that after gastrectomy only the plasma amino acid consumption test is unaffected by postoperative anatomic alterations.

Faecal chymotrypsin: a reliable index of exocrine pancreatic function

Simultaneous measurements of duodenal and faecal chymotrypsin were made in 30 children aged 3 weeks to 14 years. Apparent chymotrypsin secretion rates measured after stimulation with pancreozymin were compared with the mean faecal chymotrypsin concentration derived from three stool specimens collected at random within 72 hours of the intraduodenal test. In the 25 children who responded to pancreozymin stimulation the mean faecal chymotrypsin concentration was significantly positively correlated with the apparent chymotrypsin secretion rate. Correlation using single specimen stools collected at random was appreciably poorer. In the five children with undetectable or only traces of chymotrypsin in the duodenum after stimulation, the mean faecal chymotrypsin concentrations were only 3-10% of the lower limit of the reference interval. In a second group of 46 children with cystic fibrosis proved by sweat tests and clinical evidence of malabsorption, the chymotrypsin concentration measured in a single stool specimen collected at random was unequivocally subnormal in each case. Faecal chymotrypsin measurement is a rapid, simple, cheap, readily repeated, non-invasive test of high specificity and sensitivity. Faecal chymotrypsin should be measured before contemplating intraduodenal tests of pancreatic function.

A new faecal chymotrypsin method for evaluating the exocrine pancreatic function in patients with different pancreatic diseases

Using a new colorimetric method we measured the faecal chymotrypsin in 407 subjects, divided as follows: 252 adult subjects with a normal exocrine pancreatic function as shown by duodenal intubation, 24 adult patients with a mild to moderate pancreatic insufficiency, and 26 adult patients with severe pancreatic insufficiency. In addition, 40 healthy children, 50 children with chronic diarrhoea, and 15 with cystic fibrosis were studied before and after substituting enzyme therapy. Faecal chymotrypsin was found to be useful in evaluating the degree of exocrine functional insufficiency in subjects with diseases of the pancreas that had already been clinically ascertained. The same cannot be said for its ability to provide an early diagnosis of subjects with a slight-moderate insufficiency in exocrine pancreatic function.

Stool chymotrypsin activity measured by a spectrophotometric procedure to identify pancreatic disease in infants

The aim of this study was to assess the analytical performance of the BMC stool chymotrypsin test and its accuracy in diagnosing pancreatic disease in infants. The test utilizes a detergent which solubilizes chymotrypsin bound to stool residues, and a tetrapeptide coupled to p-nitroaniline which is specifically cleaved by chymotrypsin. We employed the IL Multistat at 30 degrees C to monitor enzyme activity as an increase in absorbance at 405 nm. The reaction was linear to 600 U/g stool. Recovery of exogenous chymotrypsin with a single detergent extraction was 98-105%, and of endogenous chymotrypsin (as determined by multiple extractions) 80-97%. Imprecision (CV) was 2.2% within-day and 2.4% between-day for the BMC control, and 2.4-5.2% for stool chymotrypsin in the range 8.3-14.4 U/g. Since the test utilises only 100 mg of stool, inhomogeneity of enzyme distribution was assessed by multiple assays on a single stool, which revealed a range of activity from 4.2-150%. We therefore recommend sampling of each stool in triplicate. With this procedure, chymotrypsin was measured in 220 consecutive stool samples submitted for fat determination from children. Applying the manufacturer's lower reference limit of 4.1 U/g, the following results were obtained (number abnormal/total number): suspected intestinal disease with normal stool fat (5/127); proven intestinal disease and increased stool fat (1/26); untreated cystic fibrosis (CF) with (19/22), and without (0/3) steatorrhea; CF with pancreatic insufficiency on replacement therapy (4/42).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of titrimetric and photometric methods for the determination of chymotrypsin catalytic activity in stool

In this report a method for the spectrophotometric measurement of stool chymotrypsin (CT) is presented and compared to the more commonly used titrimetric method. Homogenisation of specimen and dissolution of CT is examined in detail. The advantages of the photometric method lie in the small size of sample required, and its easy adaptation to manual or automated analysis with a CT-specific amide substrate.