Exocrine pancreatic function in tropical fibrocalculous pancreatic diabetes

Exocrine pancreatic function was studied by fecal chymotrypsin test in three groups of diabetic patients seen in southern India. Exocrine pancreatic insufficiency, as shown by low fecal chymotrypsin levels, was seen in 87.5% of patients with fibrocalculous pancreatic diabetes (FCPD), in 23.5% of insulin-dependent diabetes mellitus patients, and in 4.5% of non-insulin-dependent diabetes mellitus patients. There was no correlation between fecal chymotrypsin levels and serum amylase, serum lipase, age, body mass index, duration of diabetes, fasting plasma glucose, or glycosylated hemoglobin levels. The fecal chymotrypsin test is a useful additional investigation for the diagnosis of FCPD found in tropical countries.     

Advances in the enzyme diagnosis of pancreatic diseases

This paper reviews recent developments of analytical methods for the determination of alpha-amylase, of its isoenzymes, and of lipase. The evaluation of severity and etiology of acute pancreatitis by enzyme assays, e.g., pancreatic elastase 1, phospholipase A2, and routine enzymes are discussed. The limited significance of enzyme determinations as compared to imaging and endoscopic procedures for the diagnosis of chronic pancreatitis is demonstrated. Indirect "tubeless" tests for the evaluation of pancreatic exocrine insufficiency with respect to the secretion of chymotrypsin (chymotrypsin in stool and NBT-PABA test) and cholesterol esterase (pancreolauryl test) are reviewed. Finally, the superiority of morphologic investigations over biochemical tests for the timely detection of pancreatic carcinoma is shown.     

Fecal elastase-1 as a test for pancreatic function: a review.

Pancreatic elastase-1 is a specific human protease synthetized by the acinar cells. Immunoreactive elastase-1 cannot be detected in either porcine or bovine pancreatic enzyme preparations. It is very stable and, in contrast to fecal chymotrypsin, elastase is unaffected by exogenous pancreatic enzyme treatment, and correlates well with exocrine pancreatic function tests. The measurement of this proteolytic enzyme in stool by means of an enzyme-linked immunosorbent assay (ELISA) is a sensitive, specific, and relatively inexpensive non-invasive test. It is an accurate function test for patients with chronic pancreatitis confirmed by endoscopic retrograde cholangiopancreatography and computerized axial tomography. It shows higher sensitivity and specificity for exocrine pancreatic insufficiency than fecal chymotrypsin determination and is comparable to oral pancreatic function tests such as the pancreolauryl test.     

Inhibition of endogenous pancreatic enzyme secretion by oral pancreatic enzyme treatment

BACKGROUND: The existence of a feedback mechanism for exocrine pancreatic secretion in humans is controversial. Exclusion of proteases from the duodenum stimulates exocrine pancreatic secretion. Conversely, addition of exogenous enzymes could reduce the enzyme secretion. Further investigation of the feedback mechanism should be performed under the most physiological conditions. In the present study we investigated exocrine pancreatic function by measuring fecal enzyme output in healthy volunteers consuming a normal diet, before and during a time course of exogenous pancreatic enzyme supplementation. MATERIAL AND METHODS: Twenty-five healthy subjects (HS) were given two different doses (30 and 60 FIP proteases kg(-1) d(-1)) divided by the number of meals. In all subjects, fecal elastase-1 (E1) concentrations and chymotrypsin (ChT) activities were measured without and with enzyme supplements after 7 days of treatment. In eight subjects, E1 concentrations and ChT activities were measured daily for 10 consecutive days. The subjects were given a dose regimen of 100 FIP proteases kg(-1) d(-1)(divided by the number of meals) for the first 7 days. RESULTS: Oral pancreatic treatment dose-dependently inhibited endogenous pancreatic secretion measured with the use of E1 concentrations. In both regimen groups, the differences were statistically significant. The exogenous enzymes, which interfere with colorimetric method for ChT, dose-dependently increased ChT output. However, only the higher dose resulted in a statistically significant difference. In the subgroup of eight HS, time-dependent changes of fecal enzyme output occurred with a decrease of E1 concentrations and an increase of ChT activity from the second up to eighth or ninth day of the experiment. CONCLUSION: Exogenous applied pancreatic enzymes, dose- and time-dependently inhibited endogenous pancreatic secretion. The obtained results strongly support the existence of a protease mediated feedback mechanism in humans.     

Fecal chymotrypsin and elastase-1 determination on one single stool collected at random: diagnostic value for exocrine pancreatic status

OBJECTIVE: The secretin-cholecystokinin test is the "gold standard" to evaluate exocrine pancreatic function. But this direct duodenal intubation test is invasive, particularly in children, time-consuming, and expensive. For several years, indirect noninvasive tests of pancreatic insufficiency have been developed, such as fecal chymotrypsin (FChT) and fecal elastase-1 (FEL-1) measurements. Generally, elastase-1 is truly admitted to be the most relevant test of exocrine pancreatic status. However, so far, no consensus for stool collection protocol exists. The aim of our study was to investigate the diagnostic advantage from measuring fecal proteases in stool samples collected for two or three consecutive days in comparison to one single stool sample collected at random. DESIGN: A total of 69 children were divided into group A (stool samples collected for three consecutive days) and group B (stool samples collected for two consecutive days). These two groups included pancreatic-sufficient patients (PS) and severe pancreatic-insufficient patients (PI). One single determination of fecal chymotrypsin activity and of fecal elastase-1 concentration was realized on each stool. RESULTS: The same relatively important intraindividual variability of fecal proteases was observed in group A and B (mean coefficients of variation (CVs) 36% vs. 40.2% for chymotrypsin, 22.2% vs. 26.8% for elastase-1). No significant PS or severe PI diagnostic discordance was observed between 1, 2, or 3 days of stool collections. CONCLUSION: Our study clearly shows that the determination of fecal proteases on one single stool collected at random is sufficient to evaluate pancreatic exocrine status for PS and severe PI.     

Diagnosis of chronic pancreatic disease.

The diagnosis of pancreatic disease is difficult. The first step is clinical suspicion, based on the symptoms and signs. If pancreatic disease is suspected, investigation is necessary to prove this diagnosis. Investigation aims to answer two questions: a) is there pancreatic disease and b) if so, what type? The first question may be answered by demonstrating abnormal pancreatic function, using pancreatic function tests, whereas the second is answered by using techniques to demonstrate structural (anatomical) abnormalities of the pancreas. a) The methods to establish abnormal pancreatic function consist of 1. tests to demonstrate abnormal digestive capability, 2. tests to study pancreatic exocrine secretion, and 3. tests to study endocrine secretion. The tests of group 1 are: chemical fat balance study before and during enzyme replacement therapy, faecal nitrogen balance study, and the demonstration of either the malabsorption of vitamins A, D and K or the sequelae of their malabsorption (low serum calcium, high alkaline phosphatase, prolonged prothrombin time, etc.). Abnormal vitamin B12 absorption also may be present. 2. The tests designed to study pancreatic exocrine secretion are determination of the presence or absence of proteolytic enzymes in the stool, the secretion test, the pancreozymin stimulation test and the Lundh test. The serum amylase and lipase values are of little help in assessment of pancreatic function. 3. The tests to study endocrine function are the glucose tolerances test (which frequently gives abnormal results in pancreatic disease), and radioimmunoassays for insulin and gastrointestinal hormones (which may be increased in patients with functioning tumours of the islet cells). b) The techniques used to establish structural abnormalities of the pancreas are: duodenal cytology (during secretin tests), radiological techniques (abdominal survey films, barium meal, hypotonic duodenography, roentgenography of the biliary tract, barium enema, and angiography,) gastroscopy, duodensocopy, endoscopy and retrograde pancreatography, echography, scan and laparotomy. The relative value of these tests is discussed.     

Clinical value of a new fecal elastase test for detection of chronic pancreatitis

INTRODUCTION: Several pancreatic function tests exist, but their role in the diagnosis of chronic pancreatitis is controversial. Here we analyzed the clinical value of a newly available fecal elastase assay. MATERIALS AND METHODS: Fecal samples from 212 patients treated in our hospital from January to September 2002 were taken. Chronic pancreatitis was assumed when ductal alterations were present in ERCP. The severity of disease was assessed according to the Cambridge classification. Elastase (test from ScheBo, Germany) and chymotrypsin (Roche Diagnostics) were measured. As a new parameter an elastase ELISA from BIOSERV (Rostock, Germany) was employed. Specificity, sensitivity, and accuracy of each test as well as the ROC curves were calculated. RESULTS: In 45 patients (21.2%) chronic pancreatitis was diagnosed. The sensitivities of elastase from ScheBo, elastase from BIOSERV and chymotrypsin were 68.9%, 77.8%, and 57.8%, respectively. The corresponding specificities were 77.2%, 76.0%, and 52.7%. When a cut-off for the elastase tests of 100 U/ml was used the sensitivities (57.8%) and the specificities (89.2%) for both elastase tests were similar. The areas under the ROC curves for the ScheBo elastase, BIOSERV elastase, and chymotrypsin were 0.805, 0.840, and 0.628, respectively. The higher AUC of the BIOSERV test was maintained when patients with mild-moderate chronic pancreatitis (Cambridge I-II) were analyzed separately. CONCLUSION: The new elastase assay could probably replace the older test and was also much better than chymotrypsin.     

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.     

Effect of short-termed pancreatic duct obstruction on the pancreatic subcellular organellar fragility and pancreatic lysosomal enzyme secretion in rabbits.

We studied the effect of short-term (3 h) pancreatic duct obstruction (PDO) on the exocrine pancreas and on the secretion of lysosomal enzymes into the pancreatic juice of rabbits during stimulation by pancreatic secretagogues. The following evaluations were made: serum amylase levels, pancreatic water content, pancreatic amylase, trypsinogen and cathepsin B content, and output of pancreatic enzymes and lysosomal hydrolases when stimulated by secretin and caerulein as well as the distribution of cathepsin B in subcellular fraction. Cellular fragility (LDH leakage from dispersed acini) and subcellular organellar fragility (cathepsin B leakage from lysosomes and malate dehydrogenase leakage from mitochondria) were also evaluated. PDO for 3 h plus secretin infusion caused a significant rise in serum amylase levels, pancreatic water content, and pancreatic amylase and trypsinogen content due to congestion of digestive enzymes during PDO. There was also a redistribution of cathepsin B from the lysosomal fraction to the zymogen fraction and increased cellular and subcellular organellar fragility. In normal rabbits and in those with only secretin infusion, caerulein stimulated the secretion of cathepsin B into pancreatic juice. Just after PDO, the secretion of cathepsin B, amylase and trypsinogen significantly decreased. By 24 h after PDO, the output of cathepsin B stimulated by caerulein and secretin had increased significantly. Amylase and trypsinogen output were also significantly increased at this stage, in both the secretin and caerulein fractions. These results indicate that the secretion of lysosomal enzymes into pancreatic juice is stimulated by gut hormones, such as caerulein, in the normal physiological state and in pathological states, such as PDO. These results also show an important role of increased cellular and subcellular organellar fragility in the pathogenesis of pancreatic injuries induced by PDO and augmented secretion of both lysosomal enzymes and pancreatic digestive enzymes in the recovery stage after PDO and their important roles at this stage. Lysosome enzymes also seem to play some physiological roles in the pancreatic ductal system in normal physiological states as well as their roles in pathological states, because cathepsin B can activate trypsinogen, and trypsin can activate many other enzymes.     

Methodological and first clinical investigations using a new pancreatic function test]

The synthetic peptide N-benzoyl-L-tyrosyl-p-aminobenzoic acid was tested in vitro and in vivo for its chymotrypsin specificity. Comparative kinetic tests with bovine chymotrypsin and human pancreatic juice, as well as clearance tests with p-aminobenzoic acid (PABA), made this peptide seem suitable for an indirect pancreatic-function test. A testing scheme was set up for clinical use which has yielded promising preliminary results. While in 31 out of 32 healthy subjects there were normal PABA excretion rates in the urine collected over six hours, the test correlated well in 15 out of 16 cases of definite pancreatic disorder. The percentage dose excretion of PABA in the urine collected over six hours gave good correlations with the one-hour amount of chymotrypsin in the pancreozymin-secretin-test and with the concentration of chymotrypsin in the feces. These preliminary results make this test appear an appropriate screening method for pancreatopathy.     

Enzymes as agents for the treatment of disease.

The replacement of genetically deficient enzymes in patients with inherited metabolic disorders by infusion of purified enzymes or by organ transplantation has had very limited success, although good results with bone marrow transplantation have been obtained in some patients with mucopolysaccharidosis, Gaucher disease and inherited immunodeficiency diseases. Genetic engineering of the patient's lymphocytes may ultimately render these approaches redundant, at least for some of these diseases. Treatment of chronic pancreatic insufficiency and of disaccharidase deficiency with oral enzymes can be very effective; therapy can be monitored in the latter by measuring the breath hydrogen excretion and in the former by a range of tests of which stool chymotrypsin assay is the most convenient. Treatment of acute myocardial infarction by intracoronary perfusion of thrombolytic enzymes can improve both cardiac function and long-term survival if given early enough. Successful reperfusion can be identified by changes in the kinetics of serum enzyme release and clearance, especially for the isoenzymes and isoforms of creatine kinase. In cancer chemotherapy, L-asparaginase has long been a useful adjunct in the treatment of acute lymphoblastic leukemia, but recent experience suggests a role in acute nonlymphoblastic leukemia as well.     

Diagnostic utility of a new monoclonal antibody pancreatic isoamylase assay in chronic pancreatic diseases

In order to evaluate the efficacy of a monoclonal pancreatic (P) isoamylase assay in the diagnosis of chronic pancreatic disease and to compare the behavior of this test with that of amylase and elastase 1, these three enzymes were measured in the sera of 39 healthy controls, 28 patients with pancreatic cancer, 50 with chronic pancreatitis and 60 with extra-pancreatic diseases. In patients with chronic relapsing pancreatitis, increased P-isoamylase and elastase 1 values were found in similar percentages (about 70%), whereas the percentage for elevated amylase values was lower (52%). Elastase 1 was increased in 52% of patients with pancreatic cancer, while the other two enzymes were only occasionally elevated. The levels for all three enzymes were abnormal in some patients with extra-pancreatic diseases. It may be concluded that this assay for P-isoamylase determination is sufficiently sensitive and reliable in detecting pancreatic inflammation, even though some limitations concerning its specificity should be born in mind.     

Surgical resectability of pancreatic adenocarcinoma: CTA

Imaging studies play an important role in the diagnosis and management of patients with pancreatic adenocarcinoma. Computed tomography (CT) is the most widely available and best validated modality for imaging these patients. Meticulous technique following a well-designed pancreas protocol is essential for maximizing the diagnostic efficacy of CT. After the diagnosis of pancreatic adenocarcinoma is made, the key to management is staging to determine resectability. In practice, staging often entails predicting the presence or absence of vascular invasion by tumor, for which several radiologic grading systems exist. With advances in surgical techniques, the definition of resectability is in evolution, and it is crucial that radiologists have an understanding of the implications of findings that are relevant to the determination of resectability.     

A study of pancreatic secretory and intracellular enzymes in pancreatic cancer tissue, other gastrointestinal cancers, normal pancreas and serum.

Serum and tumour tissue extracts from patients with pancreatic exocrine adenocarcinoma and a number of other gastrointestinal tumours were examined for digestive and intracellular enzymes or tumour associated variants by cellogel electrophoresis. Enzymes were identified within the gel by their specific catalytic activities. Normal serum and extracts of normal pancreas were also studied. All the pancreatic secretory enzymes were present in extracts of normal pancreas; their levels were markedly reduced in tumour extracts and no characteristic isozymes were found. Alkaline phosphatase, carbonic anhydrase and a number of carbohydrate metabolising enzymes were present in all extracts; tumour associated isozymes were not consistently identified. These findings suggest that most human pancreatic exocrine cancers do not produce pancreatic secretory enzymes or intracellular isozyme variants, and that the identification of these enzymes or their isozymes is unlikely to be of practical diagnostic value.     

Rationale for the use of cimetidine in pancreatic insufficiency.

The failure of standard oral pancreatic enzyme replacement therapy to correct malabsorption in patients with advanced pancreatic insufficiency is likely due to acid-peptic inactivation of ingested enzymes. Theoretically, the use of cimetidine, an H2-receptor antagonist, in conjunction with oral enzymes, would permit greater transgastric passage of ingested enzymes with resulting improvement in intraluminal lipolysis. To test this hypothesis, we studied the effects of orally administered cimetidine in two groups of patients by utilizing a previously validated double-marker perfusion technique. Cimetidine, in varying doses, had no effect on postprandial exocrine pancreatic function in 16 duodenal ulcer patients without pancreatic disease. In six patients with pancreatic insufficiency, cimetidine produced a pronounced decrease in the output of gastric acid and secretory volume, resulting in reduction of postprandial acidity and intragastric volume. These actions of cimetidine should retard or prevent inactivation of ingested enzymes and also increase their intragastric concentration, with resulting enhancement of luminal duodenal enzyme activity. Supplemental cimetidine may thus be useful in the medical management of patients who fail to respond to routine pancreatic extract therapy alone.     

Impaired small-bowel barrier integrity in the presence of lumenal pancreatic digestive enzymes leads to circulatory shock

ABSTRACT: In bowel ischemia, impaired mucosal integrity may allow intestinal pancreatic enzyme products to become systemic and precipitate irreversible shock and death. This can be attenuated by pancreatic enzyme inhibition in the small-bowel lumen. It is unresolved, however, whether ischemically mediated mucosal disruption is the key event allowing pancreatic enzyme products systemic access and whether intestinal digestive enzyme activity in concert with increased mucosal permeability leads to shock in the absence of ischemia. To test this possibility, the small intestinal lumen of nonischemic rats was perfused for 2 h with either digestive enzymes, a mucin disruption strategy (i.e., mucolytics) designed to increase mucosal permeability, or both, and animals were observed for shock. Digestive enzymes perfused included trypsin, chymotrypsin, elastase, amylase, and lipase. Control (n = 6) and experimental animals perfused with pancreatic enzymes only (n = 6) or single enzymes (n = 3 for each of the five enzyme groups) maintained stable hemodynamics. After mucin disruption using a combination of enteral N-acetylcysteine, atropine, and increased flow rates, rats (n = 6) developed mild hypotension (P < 0.001 compared with groups perfused with pancreatic enzymes only after 90 min) and increased intestinal permeability to intralumenally perfused fluorescein isothiocyanate-dextran 20 kd (P < 0.05) compared with control and enzyme-only groups, but there were no deaths. All animals perfused with both digestive enzymes and subjected to mucin disruption (n = 6) developed hypotension and increased intestinal permeability (P < 0.001 after 90 min). Pancreatic enzymes were measured in the intestinal wall of both groups subjected to mucin disruption, but not in the enzyme-only or control groups. Depletion of plasma protease inhibitors was found only in animals perfused with pancreatic enzymes plus mucin disruption, implicating increased permeability and intralumenal pancreatic enzyme egress in this group. These experiments demonstrate that increased bowel permeability via mucin disruption in the presence of pancreatic enzymes can induce shock and increase systemic protease activation in the absence of ischemia, implicating bowel mucin disruption as a key event in early ischemia. Digestive enzymes and their products, if allowed to penetrate the gut wall, may trigger multiorgan failure and death.     

Fecal chymotrypsin: a new diagnostic test for exocrine pancreatic insufficiency in children with cystic fibrosis

The purpose of this report is to evaluate whether a new, simple, non-invasive method for chymotrypsin measurement in stools is useful for the diagnosis of exocrine pancreatic insufficiency in cystic fibrosis (CF). A hundred children aged from 2 months to 12 years were tested: 50 children had been admitted for chronic diarrhoea, 15 for cystic fibrosis and 40 acted as controls. Chymotrypsin in stools was assayed using a kinetic measurement with Succ-Ala-Ala-Pro-Phe-pNa as substrate in a simple photometric assay. In 13 of 15 children with cystic fibrosis, stool enzyme levels were always remarkably low, while all control subjects and all children not presenting cystic fibrosis had normal stool levels of chymotrypsin. Our data suggest that stool chymotrypsin measurement is a simple and reliable "tubeless" test for the evaluation of exocrine pancreatic insufficiency in children with cystic fibrosis.     

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.     

Role of endoscopic ultrasound in the diagnosis and staging of pancreatic cancer

Early diagnosis of pancreatic cancer remains a difficult task, and multiple imaging tests have been proposed over the years. The aim of this review is to describe the current role of endoscopic ultrasound (EUS) for the diagnosis and staging of patients with pancreatic cancer. A detailed search of MEDLINE between 1980 and 2007 was performed using the following keywords: pancreatic cancer, endoscopic ultrasound, diagnosis, and staging. References of the selected articles were also browsed and consulted. Despite progress made with other imaging methods, EUS is still considered to be superior for the detection of clinically suspected lesions, especially if the results of other cross-sectional imaging modalities are equivocal. The major advantage of EUS is the high negative predictive value that approaches 100%, indicating that the absence of a focal mass reliably excludes pancreatic cancer. The introduction of EUS-guided fine needle aspiration allows a preoperative diagnosis in patients with resectable cancer, as well as a confirmation of diagnosis before chemoradiotherapy for those that are not. This comprehensive review highlighted the diagnostic capabilities of EUS including the newest refinements such as contrast-enhanced EUS, EUS elastography, and 3-dimensional EUS. The place of EUS-guided biopsy is also emphasized, including the addition of molecular marker techniques.     

Two indirect tests of exocrine pancreatic function evaluated

We describe and evaluate two frequently used indirect methods for assessing exocrine pancreatic function: the N-benzoyl-L-tyrosyl-p-aminobenzoic acid test (NBT-PABA) and the pancreolauryl test. In both procedures, the patient is orally administered a substrate that is metabolized into two or more products by pancreatic enzymes. At least one of the reaction products is absorbed from the gut, conjugated, and excreted in urine, where it can be measured. Both tests can be used in the diagnosis and monitoring of cystic fibrosis, chronic pancreatitis, and pancreatic carcinoma, and in monitoring pancreatic enzyme replacement therapy to determine the appropriate dose. In comparison with the NBT-PABA procedure, the pancreolauryl test seems to have better specificity and sensitivity, undergoes almost no interference from other drugs or serum compounds, requires no complex hydrolytic conditions, and is independent of renal function.