How to manage: patient with a low faecal elastase

Clinical and Analytical Comparison of Monoclonal and Polyclonal Immunoassays for Fecal Pancreatic Elastase

BACKGROUND

Numerous immunoassays have been commercialized to determine pancreatic elastase (PE) in feces in screening for exocrine pancreatic insufficiency (EPI), but how the different assays compare to one another is controversial, especially in the context that all methods use the same cut-off values for interpreting the results obtained on the presence or absence of EPI or the degree of insufficiency if it is present. Our aim was to analytically verify a new method for determining PE, compare the results with a previous method, and verify the declared cut-off values for interpretation of the results.

METHODS

PE in the stool was assayed using a previous monoclonal enzyme-linked immunosorbent assay ("ScheBo ELISA") and a new polyclonal particle-enhanced turbidimetric immunoassay ("Bühlmann PETIA"). The direct method comparison of two immunoassays was performed in 40 samples. Clinical comparisons were conducted against each other for the binary determination of "abnormal/normal" elastase levels and the three-way determination of "severe/moderate/no" EPI in 56 samples. The indirect comparison method used external quality assessment (EQA) data to compare the monoclonal and polyclonal immunoassays for PE, and additionally compare the monoclonal ScheBo ELISA to a monoclonal chemiluminescence immunoassay ("DiaSorin CLIA").

RESULTS

Precision in the series and intra-laboratory precision for Bühlmann PETIA met the manufacturer's specifications for the concentration range of limit/lower values and the range of normal values. The Bühlmann PETIA immunoassay on different analytical platforms yielded comparable results and nearly perfect agreement in the case of three-way classification (kappa = 0.89 with 95%CI from 0.79 to 1.00. ScheBo ELISA tends to generate higher values of pancreatic elastase than the Bühlmann PETIA; agreement between the methods was moderate in the case of binary classification (kappa = 0.43; 95% CI 0.25 to 0.62), and substantial in the case of three-way classification (kappa = 0.62; 95% CI 0.50 to 0.75). EQA data analysis showed a statistically significant difference between ScheBo ELISA and Bühlmann PETIA peer groups (p = 0.031), as well as the DiaSorin CLIA and ScheBo ELISA peer groups (p = 0.010).

CONCLUSION

The ScheBo ELISA and Bühlmann PETIA do not appear to be commutable in the analytical and clinical context. Our data address a discordance between different mono- and polyclonal immunoassays for pancreatic elastase and the potential of misclassification using its universal cut-off values in screening suspected patients for exocrine pancreatic insufficiency.

What is the significance of a faecal elastase-1 level between 200 and 500μg/g?

Background

Pancreatic exocrine insufficiency is a cause of malabsorption. It is generally diagnosed if faecal elastase-1 (FE-1) levels are below 200 µg/g. Pancreatic function is assumed to be normal when faecal elastase levels are >500 µg/g. The significance of faecal elastase levels above 200 µg/g but less than 500 µg/g is unclear.

Methods

This retrospective study reports the response to treatment in patients who had an FE-1 level between 200 and 500 µg/g.

Results

Of these 82 patients, 28 were offered pancreatic enzyme replacement therapy (PERT). A clinical response, defined as an improvement in their initial symptoms after commencing PERT, was seen in 20 patients (71%), 7 with potentially predisposing conditions and 13 with functional diarrhoea. PERT particularly abolished or improved diarrhoea, steatorrhoea and flatulence.

Conclusion

Clinicians should, therefore, be aware that a trial of PERT given to patients with FE-1 levels between 200 and 500 µg/g may lead to improvement in gastrointestinal symptoms.

The clinical and laboratory impact of reporting faecal elastase-1 in watery stool samples

BACKGROUND

Low faecal elastase-1 (FE-1) results are suggestive of pancreatic insufficiency, but watery diarrhoea may lead to falsely low results.

METHODS

FE-1 results reported on watery samples over a three-year period were reviewed. Results in watery samples were compared to those from a formed sample. The follow-up of patients in whom an FE-1 result ≤199 ug/g stool (Schebo ELISA) was reported on a watery sample was also reviewed.

RESULTS

In total, 288 watery samples were identified. All results (19/19) ≥200 ug/g in watery samples were also ≥200 ug/g when measured in a formed sample from the same patient. There were 41 results ≤199 ug/g in watery samples, of which 29 (71%) were ≥200 ug/g when measured in a formed sample. Thirty-seven patients with a single FE-1 value ≤199 ug/g from a watery sample were followed up. Pancreatic Enzyme Replacement Therapy (PERT) was commenced in 15 patients. This was inappropriate in at least one patient. Reporting practice was subsequently changed to not report FE-1 values ≤199 ug/g in watery samples. This change was assessed after 12 months. Repeat samples were received from 15/56 (27%) of patients. Overall, 10/15 (67%) of samples were ≥200 ug/g on repeat. PERT was not commenced inappropriately in any of these patients.

CONCLUSIONS

There is value in measuring FE-1 in watery samples, as 144/288 (50%) of watery samples analysed were ≥200 ug/g, enabling a diagnosis of exocrine pancreatic insufficiency to be excluded. Not reporting FE-1 values ≤199 ug/g in a first-time watery stool samples appears clinically safe and has potentially reduced inappropriate diagnoses and prescribing.

Nutritional Support in Pancreatic Diseases

This review summarizes the main pancreatic diseases from a nutritional approach. Nutrition is a cornerstone of pancreatic disease and is sometimes undervalued. An early identification of malnutrition is the first step in maintaining an adequate nutritional status in acute pancreatitis, chronic pancreatitis and pancreatic cancer. Following a proper diet is a pillar in the treatment of pancreatic diseases and, often, nutritional counseling becomes essential. In addition, some patients will require oral nutritional supplements and fat-soluble vitamins to combat certain deficiencies. Other patients will require enteral nutrition by nasoenteric tube or total parenteral nutrition in order to maintain the requirements, depending on the pathology and its consequences. Pancreatic exocrine insufficiency, defined as a significant decrease in pancreatic enzymes or bicarbonate until the digestive function is impaired, is common in pancreatic diseases and is the main cause of malnutrition. Pancreatic enzymes therapy allows for the management of these patients. Nutrition can improve the nutritional status and quality of life of these patients and may even improve life expectancy in patients with pancreatic cancer. For this reason, nutrition must maintain the importance it deserves.

Associations with pancreatic exocrine insufficiency: An United Kingdom single-centre study

BACKGROUND

Pancreatic exocrine insufficiency (PEI) is said to be associated with numerous conditions both within and outside the gastrointestinal (GI) system. The majority of research has been concerned with conditions that reduce the volume of functioning pancreatic tissue or prevent adequate drainage to the small bowel, such as chronic pancreatitis, cystic fibrosis, pancreatic cancer and pancreatic resection. However, the evidence base supporting an association with extra-pancreatic conditions, such as coeliac disease, diabetes mellitus and congestive cardiac failure, is heterogeneous.

AIM

To strengthen the evidence base by studying all previously reported associations with PEI in a large cohort of outpatients.

METHODS

A single-centre retrospective study was performed. General gastroenterology outpatients tested for PEI with faecal elastase-1 (FE1) were identified and information retrieved from the electronic patient record. PEI was defined as FE1 < 200 μg/g. Patients already taking pancreatic enzyme replacement therapy were excluded. Multiple imputation was used to handle missing data. Univariable logistic regression was used to study which presenting symptoms predicted PEI. Multivariable logistic regression was used to explore the relationship between all previously reported associations and PEI.

RESULTS

Of 1027 patients were included. 182 patients (17.7%) were diagnosed with PEI. Steatorrhoea [odds ratios (OR): 2.51, 95% confidence intervals (CI): 1.58-3.98] and weight loss (OR: 1.49, 95%CI: 1.08-2.06) were the only presenting symptoms that predicted PEI. Chronic pancreatitis (OR: 7.98, 95%CI: 3.95-16.15), pancreatic cancer (OR: 6.58, 95%CI: 1.67-25.98), upper GI surgery (OR: 2.62, 95%CI: 1.32-5.19), type 2 diabetes (OR: 1.84, 95%CI: 1.18-2.87), proton pump inhibitor therapy (OR: 1.87, 95%CI: 1.25-2.80) and Asian ethnicity (OR: 2.11, 95%CI: 1.30-3.42) were significantly associated with PEI in the multivariable analysis. None of the other historically reported associations with PEI were significant after adjustment for the other variables included in our multivariable analysis.

CONCLUSION

PEI is common in patients with chronic pancreatitis, pancreatic cancer, upper GI surgery and type 2 diabetes. Proton pump inhibitor therapy may also be associated with PEI or a false positive FE1.