Pancreatic function tests: when to choose, what to use

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.

Association of fatty pancreas with pancreatic endocrine and exocrine function

Aim

The purpose of this study was to clarify whether fatty pancreas might lead to impaired pancreatic endocrine or exocrine function.

Material and methods

The study involved 109 participants who had undergone the glucagon stimulation test and N-benzoyl-L-tyros-p-amino benzoic acid (BT-PABA) test to assess pancreatic function as well as unenhanced abdominal computed tomography (CT). Pancreatic endocrine impairment was defined as ΔC peptide immunoreactivity less than 2 [mmol/L] in the glucagon stimulation test, and pancreatic exocrine impairment was defined as a urinary PABA excretion rate less than 70% on the BT-PABA test. We defined as the mean CT value of pancreas / CT value of spleen (P/S ratio) as a marker to assess fatty pancreas. We analyzed the association between fatty pancreas and pancreatic impairment using the logistic regression model. The odds ratio (OR) is shown per 0.1 unit.

Results

Pancreatic endocrine function was impaired in 33.0% of the participants, and 56.9% of those were regarded as having pancreatic exocrine impairment. The P/S ratio was significantly correlated with pancreatic endocrine impairment in univariate analysis (OR = 0.61, 95% confidence interval (CI) = 0.43–0.83, P = 0.0013) and multivariate analysis (OR = 0.38, 95% CI = 0.22–0.61, P < .0001) for all participants. Similar significant relationships were observed in both univariate (OR = 0.70, 95% CI = 0.49–0.99, P = 0.04) and multivariate (OR = 0.39, 95% CI = 0.21–0.66, P = 0.0002) analyses for the participants without diabetes (n = 93). The amount of pancreatic fat was not associated with exocrine impairment in univariate analysis (OR = 0.80, 95% CI = 0.59–1.06, P = 0.12).

Conclusion

Fatty pancreas was associated with pancreatic endocrine impairment but did not have a clear relationship with pancreatic exocrine impairment.

13C-Mixed Triglyceride Breath Test and Fecal Elastase as an Indirect Pancreatic Function Test in Cystic Fibrosis Infants

BACKGROUND

The 'gold standard' test for the indirect determination of pancreatic function status in infants with cystic fibrosis (CF), the 72-hour fecal fat excretion test, is likely to become obsolete in the near future. Alternative indirect pancreatic function tests with sufficient sensitivity and specificity to determine pancreatic phenotype need further evaluation in CF infants.

OBJECTIVE

Evaluation of the clinical utility of both the noninvasive, nonradioactive C-mixed triglyceride (MTG) breath test and fecal elastase-1 (FE1) in comparison with the 72-hour fecal fat assessment in infants with CF.

METHODS

C-MTG breath test and the monoclonal and polyclonal FE1 assessment in stool was compared with the 72-hour fecal fat assessment in 24 infants with CF. Oral pancreatic enzyme substitution (PERT; if already commenced) was stopped before the tests.

RESULTS

Sensitivity rates between 82% and 100% for CF patients with pancreatic insufficiency assessed by both the C-MTG breath test and the FE1 tests proved to be high and promising. The C-MTG breath test (31%-38%) as well as both FE1 tests assessed by the monoclonal (46%-54%) and the polyclonal (45%) ELISA kits, however, showed unacceptably low-sensitivity rates for the detection of pancreatic-sufficient CF patients in the present study.

CONCLUSIONS

The C-MTG breath test with nondispersive infrared spectroscopy (NDIRS) technique, as well as both FE1 tests, are not alternatives to the fecal fat balance test for the evaluation of pancreatic function in CF infants during the first year of life.

Nationwide epidemiological survey of early chronic pancreatitis in Japan

BACKGROUND

The world's first diagnostic criteria for early CP were proposed in 2009 in Japan. This study aimed to clarify the clinico-epidemiological features of early CP in Japan.

METHODS

Patients with early CP who were diagnosed according to the diagnostic criteria for early CP and had visited the selected hospitals in 2011 were surveyed. The study consisted of two-stage surveys: the number of patients with early CP was estimated by the first questionnaire and their clinical features were assessed by the second questionnaire.

RESULTS

The estimated number of early CP patients was 5410 (95% confidence interval 3675-6945), with an overall prevalence of 4.2 per 100,000 persons. The number of patients who were newly diagnosed with early CP was estimated to be 1330 (95% confidence interval 1058-1602), with an annual incidence of 1.0 per 100,000 persons. Detailed clinical information was obtained in 151 patients in the second survey. The male-to-female sex ratio was 1.32:1. The mean age was 60.4 and the mean age at disease onset was 55.4. Idiopathic (47.7%) and alcoholic (45.0%) were the two most common etiologies. Proportions of female and idiopathic cases were higher in early CP than in definite CP. Hyperechoic foci without shadowing and stranding were the most common findings on endoscopic ultrasonography. The clinical profiles of early CP patients who showed lobularity with honeycombing on endoscopic ultrasonography or previous episodes of acute pancreatitis were similar to those of definite CP patients.

CONCLUSIONS

We clarified the current status of early CP in Japan.

(13)C mixed triglyceride breath testing using infrared spectrometry: comparison of two devices in early infancy

BACKGROUND/OBJECTIVES

The (13)C mixed triglyceride (MTG) breath test has been proposed for the non-invasive assessment of fat digestion and absorption. To evaluate whether reference values for the adequacy of fat absorption, set in the non-dispersive infrared spectrometry (NDIRS) system software proposed for healthy children and adults using the (13)C MTG breath test, are also applicable to infants of <5 months of age.

SUBJECTS/METHODS

(13)C MTG breath testing with the NDIRS technique was performed in 54 healthy infants <5 months of age (38 breast-fed, 16 formula-fed) and six infants diagnosed with cystic fibrosis (CF) using two NDIRS devices, IRIS and FANci2.

RESULTS

The IRIS results were slightly higher compared with those assessed by the FANci2 device. The minimum cutoff value for pancreatic sufficiency (PS) is set as a cumulative percentage dose of (13)C recovered (cPDR) after 5 h of 13.0%. Pancreatic function status of six CF infants, three with PS and three with pancreatic insufficiency (PI), according to the 72 h-faecal fat balance test could be correctly determined with the (13)C MTG breath test using two NDIRS techniques. However, if these reference values had been used to determine pancreatic function status in healthy infants, 26 out of 54 infants would have been misclassified as pancreatic insufficient.

CONCLUSIONS

Although the (13)C MTG breath test with the MS technique has the potential to be a suitable assessment of fat absorption in infants, the technique of NDIRS appears too insensitive in an infant population group.

Nutritional status, fecal elastase-1, and 13C-labeled mixed triglyceride breath test in the long-term after pancreaticoduodenectomy

OBJECTIVE

This study aimed to compare the body composition, dietary intake and serum levels of vitamins and minerals, and exocrine pancreatic function in patients late after pancreaticoduodenectomy (PD) and healthy subjects.

METHODS

Fifteen patients (PD group) who had undergone PD over 1 year before the study and 15 health volunteers (control group) were included in the study. All volunteers underwent dietary intake evaluation, body composition, laboratory data, exocrine pancreatic function by elastase-1, and carbon (C )-labeled triglycerides in breath tests. The PD group subjects also underwent upper gastrointestinal endoscopy and small intestinal bacterial overgrowth analysis.

RESULTS

Nutrient intake was adequate, and there were no differences in body mass index and mineral serum levels between the groups. The PD group showed lower serum levels of retinol, α-tocopherol, and ascorbic acid. Small intestinal bacterial overgrowth occurred in 39% of the patients. Fecal elastase-1 was lower in the PD group. The PD group had a higher C peak time; the cumulative label C recovery in 7 hours was similar in both groups.

CONCLUSIONS

Fecal elastase-1 decreased, and the excretion of C in breath was similar to healthy controls. Although the data point toward an adaptation in the absorptive capacity of fats, A, C, and E hypovitaminosis indicate that some absorptive insufficiency persists late after PD.

Development and validation of an improved test for the measurement of human faecal elastase-1

BACKGROUND

Human faecal elastase-1 (FE-1) is an established biochemical test for the investigation of pancreatic exocrine insufficiency. Conventional extraction methods for FE-1 analysis can give false-positive results with watery stools. This is a major limitation as patients investigated for pancreatic disease commonly produce such stools. We have developed an improved FE-1 test that overcomes water interference by measuring the enzyme in dried faeces.

METHODS

A novel collection device for FE-1 analysis that involves drying and weighing the stool sample was developed in our laboratory and compared with a conventional wet method, E1 Quick-Prep (Schebo, Biotech AG, Germany). The concentration of faecal FE-1 was determined using a commercially available enzyme-linked immunosorbent assay method (Schebo).

RESULTS

FE-1 values obtained using the new dry extraction procedure (mean 1777 microg/g dry stool) were higher when compared with the conventional wet analysis (mean 402 microg/g stool). A 1:2 dilution in water, mimicking a loose stool, was found to affect FE-1 results obtained using the conventional wet extraction procedure. The new dry extraction method gave consistent results when water content was varied in the original stool sample.

CONCLUSION

We have demonstrated that our new device overcomes water interference, allowing results to be obtained from stool samples that would otherwise be unsuitable for FE-1 analysis.

Diffusion-weighted MRI of the pancreas: correlation with secretin endoscopic pancreatic function test (ePFT)

RATIONALE AND OBJECTIVES

To evaluate the correlation between apparent diffusion coefficient (ADC) values of the pancreas on diffusion-weighted imaging (DWI) and pancreatic exocrine function determined by HCO(3) concentration in the secretin endoscopic pancreatic function test (ePFT).

MATERIALS AND METHODS

Mean ADC values derived from 10 different points of the pancreatic gland on DWI were reviewed in 14 patients with normal (peak HCO(3) > or = 80 mEq/L) and 14 patients with abnormal (peak HCO(3) < 80 mEq/L) ePFT results. Magnetic resonance cholangiopancreatography (MRCP) images of the same patients were evaluated for the diagnosis of chronic pancreatitis. Correlation between ADC values and HCO(3) concentration as well as Cambridge scores in MRCP was performed using Spearman's correlation test.

RESULTS

Mean ADC value of the pancreas was 1.52 +/- 0.13 x 10(-3) mm(2)/s in patients with abnormal ePFT results and 1.78 +/- 0.07 x 10(-3) mm(2)/s in the normal group. There was a significant statistical difference between the ADC values of the pancreas in the two groups (P < .0001). There was also a statistically significant correlation between HCO(3) level and ADC value of the pancreas in the study patients (r = 0.771, P < .0001). Morphologic changes of the pancreas according to the Cambridge classification were also well correlated with the mean ADC values (r = -0.763, P < .0001).

CONCLUSIONS

Strong correlation between ADC value and pancreatic exocrine function as well as Cambridge score for chronic pancreatitis exists. Further studies are needed to determine the cut off ADC value for chronic pancreatitis.

A family with atypical cystic fibrosis: brother and sister with heterozygosity for both G542X and R117H

Clinical manifestations of cystic fibrosis (CF) are variable. Genetic and environmental factors that determine whether an individual will develop associated complications are still under investigation. The present study reports the genetic analysis of a family with different clinical forms of CF and addresses the difficulty of CF diagnosis in an individual with mutant alleles G542X and R117H because of the variable phenotype associated with R117H mutation. Both children in this family were heterozygous for G542X/R117H with the same thymine sequence (7T/9T) in intron 8 of CF transmembrane conductance regulator. The girl was diagnosed with CF, whereas the boy was diagnosed with azoospermia as the sole clinical manifestation. The possible implication of the hemochromatosis gene as a CF modifier locus was analyzed because the 2 children had the same genotype. No genetic differences were detected between brother and sister that explained the different clinical manifestations of CF.

Hereditary chronic pancreatitis

Hereditary chronic pancreatitis (HCP) is a very rare form of early-onset chronic pancreatitis. Apart from young age at diagnosis and a slower progression, the clinical course, morphological features and laboratory findings of HCP do not differ from those of patients with alcoholic chronic pancreatitis. Diagnostic criteria and treatment of HCP also resemble those of chronic pancreatitis of other causes. The clinical presentation is highly variable and includes chronic abdominal pain, impairment of endocrine and exocrine pancreatic function, nausea and vomiting, maldigestion, diabetes, pseudocysts, bile-duct and duodenal obstruction, and rarely pancreatic cancer. Fortunately, the disease is mild in most patients. Mutations in the PRSS1 gene, encoding cationic trypsinogen, play a causative role in chronic pancreatitis. It has been shown that the PRSS1 mutations increase autocatalytic conversion of trypsinogen to active trypsin, and thus probably cause premature, intrapancreatic trypsinogen activation, disturbing the intrapancreatic balance of proteases and their inhibitors. Other genes--such as the anionic trypsinogen (PRSS2), the serine protease inhibitor Kazal type 1 (SPINK1), and the cystic fibrosis transmembrane conductance regulator (CFTR)--have also been found to be associated with chronic pancreatitis (idiopathic and hereditary). Genetic testing should only be performed in carefully selected patients by direct DNA sequencing, and antenatal diagnosis should not be encouraged. Treatment focuses on enzyme and nutritional supplementation, pain management, pancreatic diabetes, and local organ complications such as pseudocysts and bile-duct or duodenal obstruction. The disease course and prognosis of patients with HCP is unpredictable. The risk of pancreatic cancer is elevated. Therefore, HCP patients should strongly avoid environmental risk factors for pancreatic cancer.

Hereditary chronic pancreatitis

Hereditary chronic pancreatitis (HCP) is a very rare form of early onset chronic pancreatitis. With the exception of the young age at diagnosis and a slower progression, the clinical course, morphological features and laboratory findings of HCP do not differ from those of patients with alcoholic chronic pancreatitis. As well, diagnostic criteria and treatment of HCP resemble that of chronic pancreatitis of other causes. The clinical presentation is highly variable and includes chronic abdominal pain, impairment of endocrine and exocrine pancreatic function, nausea and vomiting, maldigestion, diabetes, pseudocysts, bile duct and duodenal obstruction, and rarely pancreatic cancer. Fortunately, most patients have a mild disease. Mutations in the PRSS1 gene, encoding cationic trypsinogen, play a causative role in chronic pancreatitis. It has been shown that the PRSS1 mutations increase autocatalytic conversion of trypsinogen to active trypsin, and thus probably cause premature, intrapancreatic trypsinogen activation disturbing the intrapancreatic balance of proteases and their inhibitors. Other genes, such as the anionic trypsinogen (PRSS2), the serine protease inhibitor, Kazal type 1 (SPINK1) and the cystic fibrosis transmembrane conductance regulator (CFTR) have been found to be associated with chronic pancreatitis (idiopathic and hereditary) as well. Genetic testing should only be performed in carefully selected patients by direct DNA sequencing and antenatal diagnosis should not be encouraged. Treatment focuses on enzyme and nutritional supplementation, pain management, pancreatic diabetes, and local organ complications, such as pseudocysts, bile duct or duodenal obstruction. The disease course and prognosis of patients with HCP is unpredictable. Pancreatic cancer risk is elevated. Therefore, HCP patients should strongly avoid environmental risk factors for pancreatic cancer.

Pancreatic volume associated with endocrine and exocrine function of the pancreas among Japanese alcoholics

BACKGROUND/AIMS

The pancreas is often damaged by excessive alcohol consumption. Because alcohol-related problems and diabetes mellitus (DM) are increasing in Japan, this cross-sectional study was designed to investigate how pancreatic volume (PV, calculated using multi-slice helical computed tomography) represents alcohol consumption and both endocrine and exocrine pancreatic function among alcoholics.

METHODS

Consenting male and female inpatients undergoing psychiatric therapy for alcoholism from June 2003 to May 2004 were subjected to four-slice MCT to determine PV. Fasting plasma glucose (FPG) and serum lipase levels were examined for endocrine and exocrine pancreatic functions, respectively.

RESULTS

The average PVs of 535 male and 117 female patients (57.2 +/- 21.91 ml and 54.5 +/- 17.56 ml, respectively) were related to age and height (H) but not to body weight (W). Lipase values had a strong relationship with PV/W. Multiple regression analysis revealed weak associations between PV and both daily ethanol consumption and duration of habitual drinking. The diagnosis of DM in 109 of these alcoholics was more strongly associated with the PV/W value than with PV or PV/H.

CONCLUSION

The association of PV with endocrine and exocrine functions suggests new markers, especially PV/W, for the assessment of DM among alcoholic patients.

Diagnostik und Therapie der chronischen Pankreatitis

Chronic pancreatitis is characterized by recurrent or persisting pain. As the exocrine pancreatic insufficiency occurs early in the progression of the disease, the endocrine function may persist intact. Imaging procedures and pancreatic function tests are used to make a diagnosis. Therapy consists of pain reduction, which might require endoscopic or surgical intervention. Treatment of exocrine and endocrine pancreatic insufficiency is based on diet and substitution of pancreatic enzymes, minerals and vitamins, as well as insulin.

Review article: Pancreatic function testing

Pancreatic function tests are most commonly used to diagnose chronic pancreatitis. These tests include tests which document exocrine or endocrine gland insufficiency and tests which instead measure gradations of decreased secretory capacity. The tests in the former category generally become abnormal when advanced, longstanding chronic pancreatitis is present. Tests in the latter category, however, have the potential to detect chronic pancreatitis at an earlier stage than other available diagnostic tests, including commonly used imaging tests such as computed tomography and endoscopic retrograde cholangiopancreatography. This potential advantage of diagnostic sensitivity is, however, counterweighed by the fact that these tests which measure stimulated secretory capacity are only available at a very few referral centres. This article will review the variety of pancreatic function tests and describe their rationale, accuracy, cost, and clinical usefulness.

Chronic pancreatitis

The pathogenesis of idiopathic chronic pancreatitis remains poorly understood despite the high expectations for ascribing the pancreatic damage in affected patients to genetic defects. Neither mutations in the cationic trypsinogen gene nor mutations of the cystic fibrosis conductance regulator gene account for the chronic pancreatitis noted in most patients with idiopathic chronic pancreatitis. Attempts to find an autoimmune basis for the pancreatitis in these patients have not been very successful. The diagnosis of small duct idiopathic chronic pancreatitis remains a great source of frustration for clinicians. Such patients with negative results of radiographic studies often cannot be diagnosed unless a hormone stimulation test such as a secretin test is performed. Although the porcine biologic form of secretin, which has been used to diagnose chronic pancreatitis, became unavailable because of widespread use in the treatment of children with autism, a synthetic form of porcine secretin has now been approved by the US Food and Drug Administration and is available. The true value of endoscopic ultrasonography in diagnosing small duct chronic pancreatitis remains to be fully defined. Endoscopic ultrasonography is becoming the test of choice in detecting radiographic abnormalities in both the parenchyma and ducts of the pancreas. Endoscopic ultrasonography-guided celiac plexus block can be performed relatively easily and very safely. It can provide excellent short-term pain relief in some patients, but reliable predictors of which patients will be successful with this therapy are not yet available. Because long-term follow-up data on the use of endoscopic ultrasonography in this respect are not available, and because the pain of chronic pancreatitis is, indeed, chronic, the role of endoscopic ultrasonography-guided celiac plexus block should be limited to treating those patients with chronic pancreatitis whose pain has not responded to other modalities.