Serum elastase 1 in inflammatory pancreatic and gastrointestinal diseases and in renal insufficiency. A comparison with other serum pancreatic enzymes

Summary Serum elastase 1 has been evaluated in 115 patients with pancreatic and nonpancreatic gastrointestinal diseases and in 36 healthy controls. Increased serum elastase 1 values were found in all 27 patients with acute pancreatitis. If the diagnostic cutoff was established as the 2-fold increase above the upper normal range, sensitivity of elastase 1 (100%) was superior to pancreatic lipase (90%), immunoreactive trypsin (87%) and pancreatic amylase (78%). Specificity was 96% for elastase 1 at this cutoff. No distinction was possible between edematous and necrotizing acute pancreatitis on the basis of peak serum elastase 1 concentrations. Among 32 patients with chronic pancreatitis increased serum elastase 1 values were found in 22% and decreased values in 16% of patients, showing a striking parallelism to serum values of pancreatic lipase and immunoreactive trypsin. Specificity, established in controls and 49 patients with different gastrointestinal diseases, was 77% for elastase 1, 76% for immunoreactive trypsin, 83% for pancreatic lipase and 91% for pancreatic amylase. In addition, we investigated 21 patients with severe chronic renal diseases. In patients with renal insufficiency elastase was increased in 33%, comparable to the frequency of increased amylase and pancreatic amylase serum levels, whereas immunoreactive trypsin was increased in 95%. Immunoreactive trypsin showed a significant correlation to creatinin serum concentration, whereas the other enzymes did not.     

Serum immunoreactive elastase in diagnosis of pancreatic diseases

Diagnostic significance of serum immunoreactive elastase-1 was studied in 137 patients with pancreatic disease, 335 with various nonpancreatic diseases, and 416 healthy controls by using radioimmunoassay. Frequency of abnormally high serum elastase values exceeding 410 ng/dl was 100% in acute pancreatitis (N=14), 40% in chronic pancreatitis (N=80), and 72% in pancreatic cancer (N=43). In pancreatic cancer the mean value of serum elastase in resectable cancer (N=19) was significantly higher than that in unresectable cancer (N=24). Sensitivity, specificity, and efficiency of serum elastase in pancreatic cancer were 72.1%, 98.3%, and 95.9% against healthy controls; 72.1%, 85.9%, and 83.6% against nonpancreatic digestive diseases; and 72.1%, 60.0%, and 64.2% against chronic pancreatitis at a cutoff level of 410 ng/dl, respectively. High serum elastase could be a diagnostic clue to detect pancreatic duct obstruction due to pancreatic cancer, although further examination should be done by endoscopic retrograde pancreatography and other imaging studies.This study was supported in part by a research grant for intractable pancreatic disease and a cancer grant 58-21 from Ministry of Health and Welfare, Japan.     

Fecal calprotectin and elastase 1 determinations in patients with pancreatic diseases: a possible link between pancreatic insufficiency and intestinal inflammation

Background Fecal calprotectin determination has been demonstrated to be useful in diagnosing various inflammatory diseases of the gastrointestinal tract; however, data available for patients with pancreatic diseases are scarce. Our aim was to assess fecal calprotectin in order to evaluate the presence of intestinal inflammation in patients with pancreatic disease. Methods Eligible patients with suspected pancreatic illness were enrolled, and in all of them fecal calprotectin and elastase-1, as well as serum amylase and lipase activities, were assayed using commercially available kits. Results A total of 90 subjects (47 men, 43 women, mean age 58.6 ± 14.9 years) were enrolled: 20 (22.2%) had chronic pancreatitis; 15 (16.7%) had pancreatic cancer; six (6.7%) had chronic nonpathological pancreatic hyperenzymemia; 16 (17.8%) had nonpancreatic diseases; and 23 (25.6%) had no detectable diseases. Diarrhea was present in 19 patients (21.1%). In univariate analyses, the presence of diarrhea and low fecal elastase-1 concentrations were significantly associated (P = 0.019 and P = 0.002, respectively) with abnormally high fecal calprotectin concentration, and the multivariate analysis demonstrated that low fecal elastase-1 concentration was the only variable independently associated with a high fecal calprotectin concentration. Conclusions Pancreatic insufficiency may cause intestinal inflammation, probably because of a modification of the intestinal ecology.     

Serum amylase in patients with renal insufficiency and renal failure.

Results vary with regard to the upper limits of serum amylase seen in patients with renal failure, and very little has been reported with patients with renal insufficiency not yet requiring dialysis. To determine the level of serum amylase elevation in renal insufficiency and renal failure, we determined serum amylase values in 128 subjects with creatinine clearances less than 90 ml/min. Serum amylase remained in the normal range when creatinine clearance was greater than 50 ml/min, and did not become elevated until creatinine clearance was less than 50 ml/min. The highest serum amylase recorded in the absence of acute pancreatitis was 503 IU/L (normal, less than 128 IU/L). Serum lipase and trypsin values paralleled those for serum amylase; values remained normal when creatinine clearance was greater than 50 ml/min, and were normal or elevated when creatinine clearance was less than 50 ml/min. These results indicate that elevations of serum amylase (i.e., amylase greater than 128 but less than 500 IU/L) in asymptomatic patients with impaired renal function are not evident until creatinine clearances fall below 50 ml/min, and probably do not represent acute pancreatitis.     

Magnetic resonance imaging in pancreatic diseases: comparison with other imaging techniques.

Magnetic resonance imaging (MR) was performed in 14 healthy subjects and 16 patients with pancreatic disease. All the 16 patients were subjected to ultrasonography (USG), computed tomography (CT) and MR while endoscopic retrograde cholangiopancreatography (ERCP) was performed in 10 cases. In one patients with adenocarcinoma and two with gastrinoma, MR demonstrated abnormalities while USG and CT were normal. MR was, however, inferior to ERCP in demonstrating ductal abnormalities in chronic pancreatitis. Our initial experience suggests that MR is superior to other imaging modalities in the diagnosis and staging of pancreatic tumors; however, it is inferior to ERCP in the diagnosis of pancreatitis.     

Fate of oral enzymes in pancreatic insufficiency.

Oral pancreatic enzyme supplements, including those protected from gastric acidity by enteric coating, often achieve only partial correction of pancreatic steatorrhoea. To characterise the mechanisms involved in vivo, eight patients with steatorrhoea due to advanced pancreatic insufficiency and nine healthy controls were studied. Two sets of studies (small bowel intubation and five day faecal fat quantification) were randomly performed while patients were either on enteric coated pancreatin or equivalent placebo. A 260 cm long multilumen tube was used for double marker perfusion of two 20 cm segments located in the duodenum and in the ileum respectively. Luminal pH, flow, and trypsin and lipase activity outputs were measured at each segment for four hours postcibally. Placebo treated patients with pancreatic steatorrhoea had low enzyme outputs in the duodenal test segment and even lower outputs in the ileal segment. Pancreatin treatment significantly decreased steatorrhoea (p < 0.05) and increased luminal enzyme outputs (p < 0.05). The increase was much greater in the ileal than in the duodenal segment. Thus enteric coated pancreatin treatment abolished the normal gradient between postcibal duodenal and ileal lipase output. The results suggest that enteric coated pancreatin nearly corrects severe pancreatic steatorrhoea. The ingested lipase was utilised inefficiently, however, as luminal enzyme activity in the ileum was enhanced to a greater extent than in the duodenum, and consequently the absorptive potential of the small bowel was only partially utilised.     

Elevation of plasma truncated elastase alpha 1-proteinase inhibitor complexes in patients with inflammatory lung diseases.

Human neutrophil elastase plays an important role in the development of several inflammatory lung diseases; however, there have been relatively few investigations using plasma samples. In this report, we describe alterations in the plasma elastase:alpha 1-PI complex in patients with chronic obstructive pulmonary disease (COPD) (15 cases), COPD with infection (8), diffuse panbronchiolitis (DPB) (8), bronchiectasis (9), pneumonia (10), and the adult respiratory distress syndrome (ARDS) (14), and in 15 normal volunteers. The elastase:alpha 1-PI complex concentration was determined by an enzyme-linked immunosorbent assay. Western immunoblot analysis of the elastase:alpha 1-PI complex was also performed. Plasma elastase:alpha 1-PI complex was also performed. Plasma elastase:alpha 1-PI complex levels in patients with COPD with infection (504 micrograms/L +/- 93 micrograms/L) were significantly higher, as compared with those with COPD but without infection (118 micrograms/L +/- 9 micrograms/L) and normal volunteers (122 micrograms/L +/- 4 micrograms/L). Increased complex concentrations were also found in patients with DPB and bronchiectasis (643 micrograms/L +/- 222 micrograms/L and 558 micrograms/L +/- 198 micrograms/L, respectively) as compared with normal volunteers. Increased complex concentrations were also found in patients with pneumonia and ARDS (450 micrograms/L +/- 101 micrograms/L and 1,400 micrograms/L +/- 438 micrograms/L, respectively). Western immunoblot analysis using anti-alpha 1-PI antibody and antineutrophil elastase antibody showed two types of elastase:alpha 1-PI complexes, one with a molecular weight of 60,000 daltons (60 kilodaltons [KD]) and the other at 50,000 daltons (50 KD). Although the native 80-KD elastase:alpha 1-PI complex was detected in bronchoalveolar lavage fluid, it was not found in plasma. In summary, these results demonstrated that levels of the truncated complex were increased in patients with various inflammatory lung diseases. This truncated form may play an important role in the pathophysiology of inflammatory processes.     

Values of serum carcinoembryonic antigen and elastase 1 in diagnosis of pancreatic carcinoma

Carcinoembryonic antigen (CEA) and elastase 1 in the serum were determined by enzyme immunoassay and radioimmunoassay, respectively, in 224 healthy subjects, 49 patients with pancreatitis, 53 patients with pancreatic carcinoma and 129 patients with cancer in other organs. The CEA concentrations in the serum were significantly higher in patients with pancreatic carcinoma than in those with pancreatitis, but this concentration was not a satisfactory indicator of pancreatic carcinoma localised to allow irradication by resection as it was raised in only 47% of the patients. High CEA concentrations were also slightly, but not significantly, more frequent in patients with cancer of the pancreatic body or tail, and unresectable cancer or cancer of more than 6.0 cm in longest diameter than in those with cancer of the pancreatic head, resectable cancer or cancer of less than 6.0 cm diameter. Serum elastase 1 was raised in only 42% of the patients with pancreatic carcinoma and could not be used to distinguish patients with pancreatic carcinoma from those with pancreatitis. In contrast with CEA, however, its concentration was abnormally high significantly more frequently in patients with cancer of less than 6.0 cm in longest diameter than in those with larger tumours. It was also raised slightly, but not significantly, more frequently in those with cancer of the pancreatic head and in patients with resectable cancer than in those with unresectable cancer. A combination of these two tests raised the diagnostic rate of pancreatic carcinoma to 77% without a remarkable decrease in the specificity for pancreatic carcinoma. In particular, it raised the diagnostic rates of cases of cancer of the pancreatic head, resectable cancer and cancers of less than 3.0 cm and 3.0-6.0 cm in longest diameter. Therefore, a combination of measurements of CEA and elastase 1 in the serum is very useful for early detection of pancreatic carcinoma.     

Faecal elastase 1: not helpful in diagnosing chronic pancreatitis associated with mild to moderate exocrine pancreatic insufficiency

Background/Aim—The suggestion that estimation offaecal elastase 1 is a valuable new tubeless pancreatic function testwas evaluated by comparing it with faecal chymotrypsin estimation inpatients categorised according to grades of exocrine pancreatic insufficiency (EPI) based on the gold standard tests, thesecretin-pancreozymin test (SPT) and faecal fat analysis.
Methods—In 64 patients in whom EPI was suspected,the following tests were performed: SPT, faecal fat analysis, faecalchymotrypsin estimation, faecal elastase 1 estimation. EPI was gradedaccording to the results of the SPT and faecal fat analysis as absent,mild, moderate, or severe. The upper limit of normal for faecalelastase 1 was taken as 200 µg/g, and for faecal chymotrypsin 3 U/gstool. Levels between 3 and 6 U/g stool for faecal chymotrypsin areusually considered to be suspicious for EPI. In this study, both 3 and 6 U/g stool were evaluated as the upper limit of normal.
Results—Exocrine pancreatic function was normal in34 patients, of whom 94, 91, and 79% had normal faecal elastase 1 andfaecal chymotrypsin levels (<3 U/g and <6 U/g) respectively. Thirtypatients had EPI, of whom 53, 37, and 57% had abnormal faecal enzymelevels (differences not significant). When EPI was graded as mild,moderate, or severe, 63% of patients had mild to moderate EPI, and37% had severe EPI. In the latter group, between 73 and 91% ofpatients had abnormal faecal enzymes. In the group with mild tomoderate EPI, abnormal test results were obtained for both faecalenzymes in less than 50% of the patients (differences notsignificant). Some 40% of the patients had pancreatic calcifications.There were no significant differences for either faecal enzyme between the two groups with and without pancreatic calcifications. In 62% ofthe patients who underwent an endoscopic retrogradecholangiopancreatography (ERCP), abnormal duct changes were found.Again, there were no significant differences for either faecal enzymebetween the two groups with abnormal and normal ERCP.
Conclusion—Estimation of faecal elastase 1 is notdistinctly superior to the traditional faecal chymotrypsin estimation.The former is particularly helpful only in detecting severe EPI, but not the mild to moderate form, which poses the more frequent and difficult clinical problem and does not correlate significantly withthe severe morphological changes seen in chronic pancreatitis.

Keywords:faecal elastase 1; faecal chymotrypsin; secretin-pancreozymin test; faecal fat analysis; exocrine pancreaticinsufficiency; diagnosis

     

The commercially available ELISA for pancreatic elastase 1 based on polyclonal antibodies does measure an as yet unknown antigen different from purified elastase 1. Binding studies and clinical use in patients with exocrine pancreatic insufficiency

The measurement of fecal elastase 1 concentrations by means of an ELISA based on monoclonal antibodies (mABs) highly specific for human elastase 1 (ELISA 1) has become an accepted indirect test of the exocrine pancreatic function during the last years. Its use has been demonstrated in many clinical studies including comparison with direct function tests and ERCP morphology. Recently, a new ELISA, also named "elastase 1" based on polyclonal antibodies (pABs; ELISA 2) became available. In the present investigation we performed binding studies with purified elastase 1 as well as studies on patients with exocrine insufficiency with both ELISAs. Surprisingly, the pABs on the solid phase (catcher antibodies) of ELISA 2 did not bind purified elastase 1. These antibodies seem to react with an as yet unknown antigen associated with elastase 1. Measurement of samples from patients suspected to suffer from exocrine insufficiency showed a weak correlation of both assays but higher levels in ELISA 2, resulting in false normal results even in some patients with pancreatic steatorrhea. Since the reference range used in both assays has been established using ELISA 1, ELISA 2 must be re-evaluated in comparison to direct function tests. ELISA 2 should be renamed, since obviously it does react with an antigen (antigens) different from elastase 1.     

Molecular form of pancreatic elastase 1 in human plasma.

In order to study the molecular forms of immunoreactive pancreatic elastase 1 (IRE) in human plasma, we investigated the characteristics of proelastase 1, elastase 1, and their alpha 1-protease inhibitor (alpha 1-PI) complexes on anion-exchange (Mono Q) chromatography, gel (Superose 12) chromatography, and enzyme immunoassay systems with monoclonal antielastase 1 antibodies of different affinities for alpha 1-PI-elastase 1 and alpha 1-PI-proelastase 1 complexes. The rate of complex formation between proelastase 1 and alpha 1-PI was dependent on temperature of incubation and concentration of alpha 1-PI. At 37 degrees C, 90% of proelastase 1 was bound to alpha 1-PI during 2 h of incubation of purified human proelastase 1 with human alpha 1-PI. Similar results were also obtained by 2 h of incubation of proelastase 1 with human plasma at 37 degrees C. Therefore, under physiological conditions, neither free proelastase 1 nor elastase 1 can be detected in the human blood stream, and most IRE exists as the complex of proelastase 1 with alpha 1-PI in human plasma.