Diagnostic value of fecal chymotrypsin and trypsin assessment for detection of pancreatic disease. A comparative study

Serum and fecal pancreatic enzymes in beta-thalassemia major

CONCLUSION

This study, using indirect tests, demonstrated that exocrine pancreatic function is impaired in a proportion of patients with beta-thalassemia major (TM), though this impairment is generally mild or moderate.

BACKGROUND

Impaired structure and function of the exocrine pancreas has been reported in patients with Beta-thalassemia major.

METHODS

In this study we measured fecal fats and serum and fecal pancreatic enzymes in 30 patients (13 M, 17 F) with TM, mean age 22.1 yr (range 14-39) and compared them with those of a matched group of healthy controls. Results were correlated with age, serum ferritin, blood transfusion, and various nutritional parameters. Enzymes assays included: serum pancreatic amylase (PA), lipase (L), trypsin (T), fecal chymotrypsin (FCT), and fecal elastase (FE).

RESULTS

No patient was positive for steatorrhea. Comparison of the mean values showed a significant difference only for FE (p < 0.002). Using only the fecal tests as a reference, we found that 12 patients had FE values below the cutoff limit; of these, five had values between 100 and 185 micrograms/g, three between 50 and 99 micrograms/g and four below 50 micrograms/g. Ten patients had FCT values below the cutoff limit; seven presented impairment in both tests and six of them had FE values below 100 micrograms/g (including four diabetics). No correlations were found between enzyme values and mean serum ferritin values or mean blood consumption over the previous 3 yr. No correlation was found between FE and FCT levels or between enzymes and age.

Plasma lipase, C-peptide reactivity and human pancreatic polypeptide responses after ingestion of elemental diet in patients with chronic pancreatitis

Plasma lipase, C-peptide reactivity (CPR) and human pancreatic polypeptide (HPP) responses after ingestion of elemental diet were studied in 27 patients with chronic pancreatitis. These subjects were classified into 3 groups according to ERP findings; minimum or mild (MIP, n = 17), moderate (MOP, n = 6) and advanced (ADP, n = 4). Basal plasma lipase levels in the MIP and MOP patients were significantly higher than that in the controls (P < 0.05). Plasma CPR response (sigma delta CPR) in MIP cases were significantly higher than that in controls (P < 0.05). Also, plasma HPP (response (sigma delta HPP) in MIP cases were significantly higher than that in controls (P < 0.05). Plasma CPR and HPP responses correlated with the severity of chronic pancreatitis. Fourteen of the 17 MIP patients (82%) showed higher levels of basal lipase or sigma delta HPP in comparison to the respective normal ranges. This study suggested that the ED test may be more sensitive for detection of mild chronic pancreatitis and that it may be useful for evaluating exocrine and endocrine pancreatic functions in various stages of chronic pancreatitis.

Fecal immunoreactive lipase: a new tubeless pancreatic function test

Immunoreactive lipase (IRL) was measured in 368 stool samples from 231 individuals by means of a new enzyme-linked immunoabsorbent assay technic, to test its validity as an indicator of exocrine pancreatic insufficiency. Ninety-seven stool samples from 64 healthy volunteers showed a logarithmically normal distribution of IRL values and a median IRL concentration of 17 micrograms/g (range, 2.75-117.3 micrograms/g) with a statistically calculated lower normal limit of 4 micrograms/g. In 100 stool samples from patients with chronic pancreatitis and proven steatorrhea the median IRL concentration of 6 micrograms/g (range, 0.002-107 micrograms/g) was significantly lower than that of normal controls and of 52 stool samples from patients with chronic pancreatitis without steatorrhea (IRL, 40 micrograms/g; range, 0.55-302 micrograms/g), 45 stool samples from 23 patients with celiac disease (IRL, 96 micrograms/g; range, 6.05-563 micrograms/g), and 30 stool samples from 26 patients with chronic diarrhea (IRL, 57 micrograms/g; range, 4.2-573 micrograms/g). It is concluded that fecal IRL is a promising new enzyme test with low diagnostic sensitivity (34%) but excellent diagnostic specificity (98%) in chronic pancreatitis and for diagnostic study of chronic diarrheal disorders. In contrast to fecal chymotrypsin, the test results are unaffected by pancreatic enzyme replacement therapy.

Determination of faecal chymotrypsin concentration and 72-hour faecal chymotrypsin output in the detection of pancreatic steatorrhoea

In 96 consecutive patients who underwent a 72-h faecal fat determination because of suspected nutrient malassimilation (maldigestion and/or malabsorption) faecal chymotrypsin (F-Chym) was estimated with a commercial photometric test (Monotest Chymotrypsin), comparing F-Chym concentrations in the first 24-h stool with the total 72-h F-Chym output. In the first 24-h faeces, the F-Chym concentration, calculated as a mean of three random samples, did not significantly differ from a single value obtained after homogenization. In known pancreatic disease, a F-Chym concentration less than 3.0 U/g wet faeces distinguished well between steatorrhoic patients (n = 12) and nonsteatorrhoic (n = 13) (positive predictive value (PV), 91%; negative PV, 86%) but was less suitable as a screening test for pancreatic steatorrhoea in the unselected patient group (positive PV, 61%; negative PV, 98%). Although the estimation of 72-h F-Chym output could differentiate between various subgroups of patients to a certain extent, the positive PV for discovery of pancreatic steatorrhoea in a single patient was low. Four patients had excessively high F-Chym output and increased bile acid excretion after ileal resection (n = 3) and radiation ileitis (n = 1), respectively, possibly indicating the removal of an inhibitory mechanism of pancreatic and biliary secretion in these conditions.

Severe chronic cephalic pancreatitis: use of partial duodenopancreatectomy with occlusion of the pancreatic duct in 289 patients

Partial duodenopancreatectomy and occlusion of the remaining ductal system by Ethibloc to induce rapid exocrine atrophy for treatment of severe chronic cephalic pancreatitis was introduced in our department in January of 1978. Since then, this surgical procedure has been performed in a total of 289 patients. Postoperative morbidity was 12.2%, 5 pancreatic and 3 biliary fistulas occurred. Postoperative mortality was 1% and relapses of pancreatitis occurred in only 2.2% due to incomplete filling of ducts with Ethibloc. A total of 88.2% of patients became pain-free and symptomless, 10.8% voiced minor complaints, and 85.9% gained an averaged of 7.8 kg weight postoperatively. We conclude that Ethibloc occlusion is highly effective in inducing complete exocrine atrophy, thus abolishing the inflammatory process and preventing relapses of chronic pancreatitis and preserving the endocrine function from further impairment. This was demonstrated by biochemical assays during a 36-month follow-up in a prospective study in 23 of 289 patients. Our results compare favorably with and are superior to results from any other operative procedure for chronic cephalic pancreatitis. We consider partial duodenopancreatectomy combined with Ethibloc occlusion of the pancreatic duct the procedure of choice in the surgical treatment of severe chronic cephalic pancreatitis.

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.

Elastase 1 and chymotrypsin B in pancreatic juice and feces

A chymotrypsin-like protease was detected along with elastase 1 in pancreatic secretion and stool. This enzyme was isolated from necrobiotic human pancreas, purified, partially characterized and designated as chymotrypsin B. Quantitative studies by rocket immunoelectrophoresis indicated that neither elastase 1 nor chymotrypsin B was degraded during intestinal passage. On the basis of a clinical study, both enzymes were found to reflect pancreatic function.

Usefulness of a simple photometric determination of chymotrypsin activity in stools--results of a multicentre study

The usefulness of a new photometric test for the determination of chymotrypsin activity in stools was evaluated in a multicentre study. By release of the enzyme from stool particles with a cationic detergent solution after, in most cases, 3 min of homogenization, a photometric measurement of the enzyme activity is possible both in the clear supernatant after centrifugation and in the diluted stool homogenate. The precision of the activity measurement in stool samples with pathologically lowered and normal chymotrypsin activity is good both for in-series (CV = 2.6%, scatter 0.6-5.7%) and for day-to-day determinations (CV = 7.2%, scatter 3.9-13.9%). The results obtained by the photometric determination also exhibit a close correlation with the values measured by pH-stat titrimetry (r = 0.901). The sample-preparation system with a sample-metering chamber is easy to use and gives good agreement with determinations in which the sample metering was done by weighing out the stool (r = 0.961). The photometric test for detection of exocrine pancreatic insufficiency is easy to perform, inexpensive and does not place any undue stress on the patient.

Chymotrypsin: molecular and catalytic properties

A review on the peptide hydrolase chymotrypsin gives some characteristics concerning the structure, specificity, mechanism of activation from its precursor and catalytic activity. Problems of the active sites, allosteric alterations, changes of conformation, different behaviour against types of substrates, and suggested kinetics are shown in some detail. Finally, the diagnostic role of this serine proteinase is mentioned.

Fecal chymotrypsin levels in children with pancreatic insufficiency

The fecal chymotrypsin (FC) levels in samples collected over 24 h were determined by a new commercial colorimetric method from Boehringer Mannheim in 82 children suffering from various pancreatic disorders. The patients were divided into 4 groups, in accordance with the following etiologies: cystic fibrosis of the pancreas (CFP), chronic severe hepatic disorders (CSH), primary malabsorption syndrome (PMS) and malnutrition due to nondigestive causes (M). The control group comprised 48 children of similar ages. The 24th FC levels as U/g (mean +/- SD) were: 34 +/- 6 in the control group, 2 +/- 2 in the CFP group, 15 +/- 6 in the M group, 19 +/- 9 in the CSH group and 43 +/- 13 in the PMS group. The differences between the CFP patients and all the other groups were statistically significant. These results indicate that the FC levels may be suitable as a diagnostic indication of CFP and capable of differentiating between this disorder and other causes of pancreatic insufficiency.

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.

Exocrine pancreatic function in asymptomatic chronic alcoholics without structural pancreatic disease

In order to elucidate the functional states of the pancreas in the asymptomatic latent stage of chronic alcoholic pancreatitis, 45 chronic alcoholics with no obvious pancreatic structural abnormalities judged by endoscopic pancreatography were studied by pancreozymin-secretin test. We found three patterns of exocrine pancreatic function in alcoholics with or without cirrhosis: normal secretion (40%), hyposecretion (29%) and hypersecretion (31%). In the hyposecretory group, the amylase output proved to be impaired more frequently. In the hypersecretory group increases were observed in one or more of the following parameters, volume, bicarbonate output and amylase output. However, increase in volume was a fundamental condition in this hypersecretion. This study confirmed that exocrine pancreatic hyposecretion and hypersecretion were almost equally frequent in asymptomatic chronic alcoholics with no obvious pancreatographic abnormalities. These results suggest that ongoing exocrine pancreatic dysfunctions exist in the subclinical stage of chronic alcoholic pancreatitis.

High incidence of extrahepatic carcinomas in idiopathic hemochromatosis

In a series of 36 consecutive patients with proved idiopathic hemochromatosis and with a mean follow-up time of 8 years, 10 patients developed 11 carcinomas (30.6%). Five patients had hepatomas and six patients extrahepatic carcinoma involving lungs (four), oral cavity (one), and thyroid (one). The findings suggest a causal relationship between hemochromatosis and extrahepatic cancer. The evidence of an increased cancer risk in relation to cirrhosis and to iron toxicity are discussed.

Analysis of human pure pancreatic juice in chronic pancreatitis and cancer of the pancreas

Pure pancreatic juice was collected from 8 control subjects, 12 patients with chronic pancreatitis and 4 patients with cancer of the pancreas by endoscopic retrograde cannulation of the papilla. Samples were collected at 1 minute intervals for 20 minutes after rapid intravenous injection of secretin (Eisai, 1 U/kg) and for 10 minutes after rapid intravenous injection of CCK-PZ (Boots, 1 U/kg). Determinations of volume, bicarbonate concentration and three hydrolases (amylase, chymotrypsinogen and lipase) were made. Our tentative conclusions are (1) pancreatic enzymes are likely to be affected one after another, not in parallel fashing, in chronic pancreatitis and in cancer of the pancreas, (2) bicarbonate concentration and chymotrypsinogen or lipase are most susceptible in chronic pancreatitis and lipase secretion seems to be more susceptible than other parameters in cancer of the pancreas. Amylase is the least affected enzyme in both pancreatic diseases, and (3) determinations of chymotrypsinogen and/or lipase should be preferably performed among hydrolytic enzymes in the evaluation of exocrine pancreatic function in chronic pancreatitis and cancer of the pancreas.

Laboratory aids in the diagnosis of pancreatitis

The diagnosis of both acute and chronic pancreatitis continues to be a challenge despite the development of new techniques and the refinement of old methods. The problem is best approached by the application of a combination of tests which can provide a reasonable degree of sensitivity and specificity applicable to the different forms of pancreatitis. In acute pancreatitis an elevation of serum amylase and amylase/creatinine clearance ratio is diagnostically useful. In chronic pancreatitis, several tests are needed to enhance the diagnostic yield, and such tests can include the secretin-pancreozymin test, ERCP, fecal fat measurement, Lundh test meal, and the administration of the synthetic peptide BZ-Ty-PABA.

Immunochemical quanitation of pancreatic endopeptidases in the intestinal contents of germfree and conventional rats

Two electrophoretically distinct trypsins and chymotrypsins and an elastolytic enzyme were isolated from rat pancreatic juice. Rabbit antisera against these enzymes were produced, and with an immunochemical technique the trypsins, chymotrypsins, and elastase were studied in the intestinal contents of conventional and germfree rats. In both types of rat the anionic trypsin and chymotrypsin were the most abundant and found in higher concentrations in the distal than in the proximal small intestine. The cecal and fecal concentrations of anionic trypsin were markedly higher in the germfree rat when compared to the conventional rat. Cymotrypsin was undetectable in the large intestine of either the conventional or germfree rat when this technique was used. Immunoreactive elastase was found in greater amounts in the distal small intestine, and high concentrations were demonstrated in the cecal contents and feces of the germfree rat. In contrast, no immunoreactive elastase was detected in the large intestine of the conventional rat. Gel filtration indicated that the immunoreactive anionic trypsin and elastase found in fecal extracts were of about the same molecular size as the native enzymes. The findings suggest that the intestinal microflora is instrumental in the inactivation and degradation of pancreatic trypsin and elastase but not chymotrypsin.

Elevated fecal levels of endogenous pancreatic endopeptidases after antibiotic treatment

Feces from normal and antibiotic-treated persons were analyzed for the content of immunoreactive trypsin and elastase. In the control group the mean concentration of immunoreactive trypsin was 13 microgram per g feces as compared to 147 in the antibiotic-treated group. Elastase was demonstrable in only 3 of 30 samples in the control group but in 20 of 26 in the antibiotic-treated group. The decreased inactivation of pancreatic proteases must depend on an altered intestinal microflora. The results suggest that reestablishment of a normal enteric flora may take months after the short time oral administration of antibiotics.

Functional, chemical, and clinical aspects of proteolytic enzymes in the alimentary canal

Knowledge of the structure and catalytic function of the pancreatic proteases has increased rapidly in recent years. These advances have been less spectacular in the case of pepsin, and information concerning mucosal enzymes of the small intestine and colon has not even reached the point where one can be certain of their number, far less their nature. The role of these enzymes in disease processes is probably not significant so far as the alimentary tract is concerned, and it is not even certain that the pancreatic proteases influence the course of acute pancreatitis -- they are of more interest to the clinician as diagnostic aids. Since undesirable consequences result from their deficient output, future research should be directed towards improving replacement therapy.

Laboratory aids to diagnosis--enzymes

A summary is presented of those organ specific enzyme assays traditionally used in evaluation of the patient with cancer. In addition, the use of certain serum enzymes such as gamma-glutamyl transpeptidase, phosphohexose isomerase or 5'-nucleotidase as aids in following the course of the disease, particularly in patients with metastatic spread to the liver is outlined. Also considered is the utility of enzyme analysis in biopsy tissue, biologic fluids, and washings of body cavities. Newer enzymes are considered which might, in the future, be developed as diagnostic tools or as probes for the understanding of the etiology of cancer.

A new, highly sensitive and specific assay for chymotrypsin

1. A simple, highly sensitive, specific fluorometric method for the determination of chymotrypsin is described. 2. The new substrate utilized in this assay, N-glutaryl-glycyl-glycyl-l-phenylalanine beta-naphthylamide (GGPNA), is readily soluble in water, stable and highly specific for chymotrypsin. It is not degraded by a large excess of carboxypeptidase B, elastase, thrombin or plasmin and is virtually resistant to trypsin. 3. GGPNA is extremely sensitive to the action of chymotrypsin and permits detection of enzyme concentrations as low as 1 ng/ml. Linearity between enzyme concentration and fluorescence produced is maintained up to at least 3000 ng/ml. 4. alpha2-Macroglobulin-bound chymotrypsin hydrolyzes GGPNA at a rate about 2/3 of that exhibited by the free enzyme. 5. Bile pigments in amounts normally found in duodenal juice or traces of blood do not interfere with the assay. 6. GG PNA which releases beta-naphthylamine upon hydrolysis is suitable also for colorimetric and histological determination of chymotrypsin.

Trypsin and chymotrypsin in duodenal aspirate and faeces in response to secretin and cholecystokinin-pancreozymin

The secretion of trypsin and chymotrypsin into the duodenum in response to secretin and CCK-PZ has been compared with the faecal excretion of the enzymes following similar stimulation in 47 individuals undergoing clinical investigation. The faecal output of chymotrypsin correlated well, but trypsin less satisfactorily, with the secretion of the respective enzymes into the duodenum. The faecal excretion of chymotrypsin following stimulation with secretin and CCK-PZ can therefore be used as an index of pancreatic enzyme-secretory capacity.

Synthetic peptides in the diagnosis of exocrine pancreatic insufficiency in animals

A new approach in the diagnosis of exocrine pancreatic insufficiency has been evaluated in animals. The method involves the oral administration of a chymotrypsin-labile peptide which contains p-aminobenzoic acid (PABA) as a tracer group. In the small bowel in the presence of chymotrypsin, the PABA is split from the peptide and is rapidly absorbed. The amount of PABA (as total aromatic amines) recovered in the urine during the six hours after the dose is used as an index of exocrine pancreatic function. The procedure has been shown to be reliable in detecting surgically induced pancreatic insufficiency in rats, swine, and dogs.

The interrelationships of pancreatic enzymes in human duodenal aspirate

The interrelationships of proteolytic enzymes and amylase have been studied in the duodenal aspirate obtained from subjects with normal and abnormal pancreatic function during stimulation with secretin and pancreozymin. While the relationship of trypsin to chymotrypsin was independent of stimulus and presence of pancreatic disease the ratio of proteolytic enzymes to amylase rose when the degree of stimulation of the pancreas was increased. Patients with recent acute pancreatitis and with chronic pancreatitis tended to have more severe impairment of secretion of proteolytic enzymes than of amylase. In routine tests of pancreatic function both proteolytic and non-proteolytic enzymes should be measured, both because an abnormal ratio may be of diagnostic significance and because the two different groups of enzymes provide mutual checks of the secretory capacity of pancreatic enzymes.