Automated spectrophotometric bicarbonate analysis in duodenal juice compared to the back titration method

Endoscopic Pancreatic Function Testing (ePFT) in Children: A Position Paper From the NASPGHAN Pancreas Committee

Endoscopic pancreatic function testing (ePFT) is one of the few ways to directly diagnose exocrine pancreatic insufficiency, and considerable confusion regarding indications, utility, and interpretation of the test remains. This position paper of the Pancreas Committee of the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition reviews the history and indications for ePFT in children. We compare various methods in current practice and determine their strengths and limitations, and based on data from children and adults we provide guidance on a protocol on how to perform ePFT in children. Lastly, we pose areas in need of further research relating to ePFT in children.

Report on the Short Endoscopic Exocrine Pancreatic Function Test in Children and Young Adults

OBJECTIVES

Endoscopic pancreatic function test (ePFT) has been in use for exocrine function testing since the 1990s. In patients, short ePFT assesses acinar function, unlike the longer version for ductal function in adults. The present study summarizes characteristics of 1913 short ePFTs (S-ePFT) performed at 2 centers since 2001.

METHODS

The main indications in patients presenting at ages infancy to 24.3 years, for the S-ePFT were failure to thrive, weight loss, diarrhea, and abdominal pain with bloating. Secretin was administered as bolus, and 4 aliquots of fluid were collected between 4 and 10 minutes after administration. Amylase, lipase, trypsin, and chymotrypsin activities were measured in the laboratory.

RESULTS

The pH of consecutive samples increased by 0.3 to 0.7. Overall, 36.7% had abnormal S-ePFT with selective amylase deficiency (9.5%) and generalized enzyme deficiency (8.9%) being the most frequent. Retest reproducibility, repeatability, and clinical validity were high. By adding S-ePFT to endoscopy for the suspicion of malabsorption, the abnormal findings increased by 36.9%.

CONCLUSIONS

Short ePFT assesses pancreatic acinar function in a reliable and clinically meaningful way in patients. Diagnostic yield of endoscopy increased substantially albeit with increased sedation time. By S-ePFT ductal function, cytokines and proteomics can also be assessed.

Assessment of Exocrine Pancreatic Function During Endoscopy in Children

This article will review briefly the physiology of pancreatic enzyme secretion and the role of stimulated endoscopic testing for assessing exocrine pancreatic function. Published studies in both the pediatric and adult literature are reviewed. The technique and utility of endoscopic pancreatic function testing as the method of choice in the differential diagnosis of pancreatic disorders in childhood is described. Finally, emerging, clinically useful markers that can be measured in the pancreatic fluid will be described.

Analysis of lipase activity in duodenal juice. Comparison of an automated spectrophotometric assay to a fluorometric microplate assay, and factors affecting sample stability

BACKGROUND

Direct pancreas function testing (DPFT) has been regarded as gold standard for assessment of exocrine pancreas function. One of the outcomes from DPFT is pancreatic lipase activity in duodenal juice, but no standard assay for measuring pancreas lipase activity in duodenal juice exists.

AIMS

To optimize and evaluate an autoanalyzer assay for measuring lipase activity in duodenal juice.

METHODS

We used samples of duodenal juice from our biobank, collected through a short endoscopic secretin test in patients with suspected exocrine pancreas insufficiency. Samples were analyzed on a Cobas autoanalyzer (Roche Diagnostics), using a colorimetric, kinetic enzyme activity assay. We compared stability of samples diluted in saline to samples diluted in 3-(N-morpholino) propane sulfonic acid (MOPS) buffer added bovine serum albumin (BSA). Results from the Cobas assay were compared to Confluolip method, a fluorometric, kinetic enzyme assay, modified to fit into a microplate setting.

RESULTS

We tested the stability of 54 samples from 21 patients. Diluting samples with MOPS buffer added BSA gave stable results, and was superior to diluting samples in saline. We compared the two assays in 50 samples from 20 patients and found a good correlation between the two assays (r = 0.91, p < .001). There was a significant proportional bias between the two assays, but no significant systematic bias.

CONCLUSION

Pancreatic lipase activity in duodenal juice samples diluted in MOPS buffer added BSA is stable for one hour at room temperature. Quantification of lipase activity in duodenal juice using a standard automated activity assay has comparable accuracy to a manual fluorometric method.

An efficient headspace gas chromatographic technique for determining humic acid content in fertilizer

A fast, convenient and commercially available approach for analyzing humic acid content in fertilizer using headspace gas chromatography (HS-GC) is presented in this paper. Humic acid is converted into carbon dioxide based on the oxidation of humic acid in strong acidic medium and can be measured via automatic HS-GC. Conditions for the alkaline extraction and the humic acid oxidation process are also optimized. The new technique proved to be precise (RSD ≤ 3.59%) and accurate (relative errors≤9.46% as compared with the spectrophotometric approach). The newly established technique presents a practical tool to routinely analyze humic acid content in fertilizer during the fertilizer production.

Analysis of amylase in duodenal juice - Automated kinetic spectrophotometric analysis versus manual colorimetric endpoint assay

OBJECTIVE

The measurement of duodenal amylase by a colorimetric end-point assay has been the most used method for amylase activity analyses. The method is manual, time consuming and dependent on specialized equipment. In this study, we compare an automated kinetic spectrophotometric method for pancreatic amylase measurement in duodenal juice with a standardized colorimetric end-point assay.

METHODS

We used specimen of duodenal juice at random from a biobank obtained by short endoscopic secretin test in patients with suspected exocrine pancreatic failure of different reasons. Duodenal juice was tested for amylase activity with a conservative manual colorimetric endpoint assay (Phadebas Amylase test, Magle AB) and an automated enzymatic kinetic spectrophotometric method using standard reagents for pancreatic amylase activity for Cobas c111 (Roche Diagnostics).

RESULTS

52 samples for assay of amylase were analyzed in pairs. Correlation between measurements with the two methods was r = 0.99 (p < 0.001), linear regression 0.99 (p < 0.001).

CONCLUSION

Quantification of duodenal amylase activity with automated spectrophotometry has excellent correlation to measurements made by the manual method. This allows for standardized, center independent analyses of duodenal amylase for the assessment of acinar pancreatic function.