A randomized crossover study of secretin-stimulated endoscopic and dreiling tube pancreatic function test methods in healthy subjects

AGA-PancreasFest Joint Symposium on Exocrine Pancreatic Insufficiency

Exocrine pancreatic insufficiency (EPI) is a clinically defined syndrome based on the physician's assessment of a patient's maldigestion. However, current clinical definitions are inadequate in determining (1) the threshold of reduced pancreatic digestive enzyme secretion that determines "pancreatic insufficiency" in an individual patient; (2) the role of pancreatic function tests; (3) effects of differing metabolic needs, nutrition intake, and intestinal function/adaptation (4) when pancreatic enzyme replacement therapy is needed; and (5) how to monitor and titrate multiple therapies. Experts and key opinion leaders were invited to PancreasFest 2021 to discuss and help clarify mechanistic issues critical to defining EPI and to address misconceptions and barriers limiting advancements in patient care. Clinically EPI is defined as inadequate delivery of pancreatic digestive enzymes to meals to meet nutritional needs and is reversed with appropriate treatment. A new mechanistic definition of EPI was proposed that includes the disorders essence and character: (1) EPI is a disorder caused by failure of the pancreas to deliver a minimum/threshold level of specific pancreatic digestive enzymes to the intestine in concert with ingested nutrients, followed by enzymatic digestion of a series of individual snacks and meals over time to meet nutritional and metabolic needs, given (a) the specific macronutritional and micronutritional needs; (b) nutrient intake; (c) exocrine pancreatic function; and (d) intestinal anatomy, function, diseases, and adaptative capacity. (2) EPI is characterized by variable deficiencies in micronutrients and macronutrients, especially essential fats and fat-soluble vitamins, by gastrointestinal symptoms of nutrient maldigestion and by improvement or correction of nutritional state with lifestyle changes, disease treatment, optimized diet, dietary supplements, and/or administration of adequate pancreatic enzyme replacement therapy. EPI is complex and individualized and multidisciplinary approaches are needed to optimize therapy. Better pancreas function tests and biomarkers are needed to diagnose EPI and guide treatment.

Minimal Change Patients Versus Obvious Chronic Pancreatitis: A Comparison of Classical Secretin Stimulation Testing Results

OBJECTIVES

The objective was to assess if the peak bicarbonate level during secretin stimulation testing (SST) differs between patients with minimal change (or small duct) chronic pancreatitis (CP) versus those with obvious CP (or large duct) versus those without CP.

METHODS

Two hundred nineteen patient records at the University of Florida who had been referred for SST were analyzed for peak bicarbonate, total volume of juice collected, age, sex, and clinical presentation.

RESULTS

Fifty-one patients with minimal change CP were identified. Thirty-three patients were felt to have advanced CP, and 135 patients did not have CP by clinical criteria. The peak bicarbonate and total volume of pancreatic juice collected was significantly different (P < 0.001) between all 3 groups by multiple comparison testing. The peak bicarbonate of advanced CP and minimal change groups was less than controls (P < 0.001). There was a significant difference (P < 0.05) on direct testing between peak bicarbonate in advanced CP and minimal change CP.

CONCLUSIONS

The peak bicarbonate and volume measured during SST differs among patients with minimal change CP, advanced CP and in disease controls. These results could be useful in diagnosing minimal change/early CP.

EUS pancreatic function testing and dynamic pancreatic duct evaluation for the diagnosis of exocrine pancreatic insufficiency and chronic pancreatitis

BACKGROUND AND AIMS

EUS and endoscopic pancreatic function tests (ePFTs) may be used to diagnose minimal-change chronic pancreatitis (MCCP). The impact of evaluation for exocrine pancreatic insufficiency (EPI) and real-time assessment of EUS changes after intravenous secretin on the clinical diagnosis of MCCP is unknown.

METHODS

Patients with suspected MCCP underwent baseline EUS assessment of the pancreatic parenchyma and measurement of the main pancreatic duct (B-MPD) in the head, body, and tail. Human secretin 0.2 μg/kg was given intravenously followed 4, 8, and 12 minutes later by repeat MPD (S-MPD) measurements. Duodenal samples at 15, 30, and 45 minutes were aspirated to assess bicarbonate concentration. Endoscopists rated the percentage clinical likelihood of chronic pancreatitis (1) before secretin; (2) after secretin but before aspiration; and (3) after bicarbonate results.

RESULTS

A total of 145 consecutive patients (mean age, 44±13 years; 98 females) were diagnosed with EPI (n = 32; 22%) or normal exocrine pancreatic function (n = 131, 78%). S-MPD/B-MPD ratios in the tail 4 and 8 minutes after secretin were higher in the group with normal exocrine function. Ratios at other times, locations, and duodenal fluid volumes were similar between the 2 groups. A statistically significant change in the median percentage likelihood of chronic pancreatitis was noted after secretin in all groups. The sensitivity and specificity of EPI for the EUS diagnosis of chronic pancreatitis (≥5 criteria) were 23.4% (95% confidence interval, 12.3-38.0) and 78.6% (95% confidence interval, 69.1-86.2), respectively.

CONCLUSION

Real-time EUS findings and ePFTs have a significant impact on the clinical assessment of MCCP. The diagnosis of EPI shows poor correlation with the EUS diagnosis of MCCP. (Clinical trial registration number: NCT01997476.).

Breath testing for the diagnosis of pancreatic disease

PURPOSE OF REVIEW

Pancreatic function tests are mainly used for the diagnosis of exocrine pancreatic insufficiency (EPI) in patients with pancreatic diseases or after pancreatic or gastric surgery. Breath tests evaluate not just pancreatic secretion but the digestion capacity of the pancreas. These tests are good candidates for the diagnosis of EPI as they are noninvasive, accurate and easy to apply to clinical practice.

RECENT FINDINGS

The C-labelled mixed triglyceride (MTG) breath test has been optimized and validated against adequate reference methods for the diagnosis of EPI in patients with chronic pancreatitis and for the evaluation of the efficacy of pancreatic enzyme replacement therapy (PERT). In addition, reported C-MTG breath test results in patients with other pancreatic diseases and after pancreatic and gastric surgery support the accuracy and clinical applicability of this test. The evidence of pancreatic function breath tests with other C-labelled substrates is limited.

SUMMARY

Increasing evidence supports the accuracy and clinical usefulness of the C-MTG breath test for the diagnosis of EPI and the evaluation of the efficacy of PERT in different clinical conditions. Commercial availability of this test is required for a wide clinical use. The use of optimized and validated breath test protocols is mandatory.

Pancreatic exocrine insufficiency and cardiovascular risk in patients with chronic pancreatitis: A prospective, longitudinal cohort study

BACKGROUND AND AIM

Previous studies have suggested that chronic pancreatitis (CP) is associated with increased risk of cardiovascular (CV) disease independently of other major risk factors. We evaluated the risk of CV events in a well-phenotyped cohort of patients with CP and its association with pancreatic exocrine insufficiency (PEI) among other CV risk factors.

METHODS

This was a prospective, longitudinal cohort study of patients with CP, followed up at the Pancreas Unit of the University Hospital of Santiago de Compostela, Spain.

RESULTS

Four hundred thirty patients were included (mean 47.8 ± 14.4 years of age, 79.1% male). Mean follow-up was 8.6 ± 4.6 years. CP etiology was toxic (alcohol and/or smoking) in 290 patients (67.4%). PEI and pancreatogenic diabetes mellitus (DM) were present in 29.3% and 29.5% of the patients, respectively. A total of 45 CV events was recorded (10.5%); 21 patients had a major CV event (stroke or myocardial infarction) and 27 developed clinically relevant peripheral arterial disease. A higher incidence of CV events was recorded in patients with PEI than in those without (incidence rate ratio 3.67, 95% confidence interval [CI] 1.92-7.24; P < 0.001). In the multivariate analysis, PEI without DM (OR 4.96; 95% CI 1.68 to 14.65), coexistence of PEI and DM (OR 6.54; 95% CI 2.71 to 15.77), arterial hypertension (OR 3.40; 95% CI 1.50 to 7.72), and smoking (OR 2.91, 95% CI 1.07 to 7.97) were independently associated with increased CV risk.

CONCLUSIONS

Together with known major CV risk factors like smoking and hypertension, PEI is significantly associated with the risk of CV events in patients with CP.

Pancreatic Insufficiency: What Is the Gold Standard?

Endoscopic pancreatic function testing assesses exocrine insufficiency and chronic pancreatitis. Indirect pancreatic function tests have limited sensitivity and specificity in early disease stages. Magnetic resonance cholangiopancreatography shows promise in detecting early changes as a direct measure of pancreatic function. This article summarizes the evolution of pancreatic function testing and highlights areas for future research, such as development of diagnostic biomarkers to stratify disease severity and targeted therapies to retard disease progression.

Increased Risk of Mortality Associated With Pancreatic Exocrine Insufficiency in Patients With Chronic Pancreatitis

BACKGROUND

Pancreatic exocrine insufficiency (PEI) is a common serious complication in chronic pancreatitis (CP); however, little is known about its effect on mortality in these patients. In this study, we assessed the mortality risk of PEI in patients with CP.

STUDY

A prospective, longitudinal cohort study conducted in patients with CP under long-term follow-up. CP and PEI were diagnosed using pancreatic imaging and the C-labeled mixed triglyceride breath test, respectively. Multivariate analysis was performed to evaluate the impact of PEI and other clinical features on mortality risk.

RESULTS

Patients (N=430) were analyzed (79.1% male; mean age, 47.8 y) during a mean follow-up of 8.6±4.6 years. PEI prevalence was 29.3% and mortality was 10.9%. Most frequent causes of death were cancer (40.4%), infection (21.3%), and acute cardiovascular event (14.9%). Multivariate analyses showed associations between increased mortality and presence of PEI [hazard ratio (HR), 2.59; 95% confidence interval (CI), 1.42-4.71; P<0.003], liver cirrhosis (HR, 3.87; 95% CI, 1.95-7.69; P<0.001), age at diagnosis (HR, 1.05; 95% CI, 1.03-1.09; P<0.001), toxic etiology of CP (HR, 3.11; 95% CI, 1.11-8.70; P<0.05) and respiratory comorbidity (HR, 2.19; 95% CI, 1.12-4.31; P<0.03). Nutritional markers were significantly lower in patients with PEI versus those without PEI (P<0.001) and in those who died versus survivors (P<0.001).

CONCLUSIONS

PEI was a significant independent risk factor for mortality in patients with CP. These results support further research into the optimal treatment of PEI to reduce mortality in this population.

Method Performance of Bicarbonate and Electrolytes by Use of Duodenal Fluid for Assessment of Exocrine Pancreatic Function

BACKGROUND

Evaluation of exocrine pancreatic insufficiency is challenging for both clinicians and laboratories. Indirect pancreatic function tests such as serum trypsinogen, fecal elastase, and fecal fat measurements are moderately sensitive for diagnosis of advanced chronic pancreatitis but show reduced sensitivity and specificity for diagnosis of early disease. An alternative is the endoscopic pancreatic function test, which uses duodenal secretions after administration of IV secretin. Samples are collected at various times via the endoscopic tube and then analyzed for bicarbonate, sodium, potassium, and chloride.

METHODS

Precision, linearity, method comparison, and stability studies were performed on the Beckman Coulter AU5822 chemistry analyzer with duodenal fluid. Comparison with the Vitros 4600 dry slide chemistry instrument was used to interrogate differences between methods.

RESULTS

All assays produced a CV <2% without any measurable effects from the endoscopy fluid matrix and showed acceptable imprecision near the limit of detection (CV < 5%). All analytes showed linear dilution across the analytical measuring range. All the calculated error biases from dilutions were within 50% of the CLIA-allowable error for serum for each of the respective analytes. The calculated slopes ranged from 0.841 to 1.274 when compared to the Vitros 4600. Stability studies demonstrated that sodium, potassium, chloride, and bicarbonate remained stable after storage at -20 °C and after multiple freeze-thaw cycles. The percent change for all analytes was <5% mmol/L.

CONCLUSIONS

The AU5800 series demonstrated adequate performance for the analysis of bicarbonate in duodenal fluid and therefore can be used for assessment of exocrine pancreatic function. However, notable discrepancies were observed for sodium, potassium, and chloride between the AU5800 series and the Vitros 4600.

Comparison of Combined Endoscopic Ultrasonography and Endoscopic Secretin Testing With the Traditional Secretin Pancreatic Function Test in Patients With Suspected Chronic Pancreatitis: A Prospective Crossover Study

OBJECTIVE

We aimed to determine the feasibility and accuracy of a combined endoscopic ultrasonography (EUS) with a shortened pancreatic function testing (sEUS) for structural and functional assessment using a single instrument in patients with suspected chronic pancreatitis (CP).

METHODS

We completed a prospective crossover study, enrolling patients with suspected CP. Patients who underwent both traditional 1-hour secretin pancreatic function test (sPFT) and sEUS were included in the analysis. We compared study results for test concordance and for correlation of peak bicarbonate concentrations.

RESULTS

Eleven (64.7%) of 17 patients had concordant sPFT and sEUS findings when the cutoff for peak bicarbonate was 80 mEq/L. Six patients had discordant findings with a negative sPFT and positive sEUS. This poor concordance suggests that sEUS is an unreliable functional test. Lowering the sEUS cutoff to 70 mEq/L resulted in improved concordance (64.7% vs 70.6%). Finally, there was no significant correlation between peak bicarbonate concentrations (r = 0.47; 95% confidence interval, -0.02 to 0.79) in these 2 functional tests.

CONCLUSIONS

We demonstrate poor concordance between sPFT and sEUS suggesting that a combined shortened functional and structural test using a single instrument may not be a feasible test for diagnosis of suspected CP when a cutoff of 80 mEq/L is used.

Diagnosis of Chronic Pancreatitis Incorporating Endosonographic Features, Demographics, and Behavioral Risk

OBJECTIVES

Diagnosing chronic pancreatitis remains challenging. Endoscopic ultrasound (EUS) is utilized to evaluate pancreatic disease. Abnormal pancreas function test is considered the "nonhistologic" criterion standard for chronic pancreatitis. We derived a prediction model for abnormal endoscopic pancreatic function test (ePFT) by enriching EUS findings with patient demographic and pancreatitis behavioral risk characteristics.

METHODS

Demographics, behavioral risk characteristics, EUS findings, and peak bicarbonate results were collected from patients evaluated for pancreatic disease. Abnormal ePFT was defined as peak bicarbonate of less than 75 mEq/L. We fit a logistic regression model and converted it to a risk score system. The risk score was validated using 1000 bootstrap simulations.

RESULTS

A total of 176 patients were included; 61% were female with median age of 48 years (interquartile range, 38-57 years). Abnormal ePFT rate was 39.2% (69/176). Four variables formulated the risk score: alcohol or smoking status, number of parenchymal abnormalities, number of ductal abnormalities, and calcifications. Abnormal ePFT occurred in 10.7% with scores 4 or less versus 92.0% scoring 20 or greater. The model C-statistic was 0.78 (95% confidence interval, 0.71-0.85).

CONCLUSIONS

Number of EUS pancreatic duct and parenchymal abnormalities, presence of calcification, and smoking/alcohol status were predictive of abnormal ePFT. This simple model has good discrimination for ePFT results.

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

OBJECTIVES

We have recently evaluated a short endoscopic secretin test for exocrine pancreatic function. Bicarbonate concentration in duodenal juice is an important parameter in this test. Measurement of bicarbonate by back titration as the gold standard method is time consuming, expensive and technically difficult, thus a simplified method is warranted. We aimed to evaluate an automated spectrophotometric method in samples spanning the effective range of bicarbonate concentrations in duodenal juice. We also evaluated if freezing of samples before analyses would affect its results.

METHODS

Patients routinely examined with short endoscopic secretin test suspected to have decreased pancreatic function of various reasons were included. Bicarbonate in duodenal juice was quantified by back titration and automatic spectrophotometry. Both fresh and thawed samples were analysed spectrophotometrically.

RESULTS

177 samples from 71 patients were analysed. Correlation coefficient of all measurements was r = 0.98 (p < 0.001). Correlation coefficient of fresh versus frozen samples conducted with automatic spectrophotometry (n = 25): r = 0.96 (p < 0.001) CONCLUSIONS: The measurement of bicarbonate in fresh and thawed samples by automatic spectrophotometrical analysis correlates excellent with the back titration gold standard. This is a major simplification of direct pancreas function testing, and allows a wider distribution of bicarbonate testing in duodenal juice. Extreme values for Bicarbonate concentration achieved by the autoanalyser method have to be interpreted with caution.

Diagnostic Accuracy of a Short Endoscopic Secretin Test in Patients With Cystic Fibrosis

OBJECTIVE

Short endoscopic secretin tests for exocrine pancreatic function are not properly evaluated in cystic fibrosis (CF).

METHODS

Patients with CF and healthy controls (HCs) underwent endoscopic collection of duodenal juice between 30 and 45 minutes after secretin stimulation. Duodenal juice was analyzed for HCO3 concentration and pancreatic enzyme activities. Stool was analyzed for fecal elastase.

RESULTS

Thirty-one patients with CF and 25 HCs were tested. Patients were classified as exocrine pancreatic sufficient (n = 13) or insufficient (n = 18). Both bicarbonate concentrations and enzyme activities in duodenal juice differentiated patients with CFI from patients with CFS and HC (P < 0.001). The population displays strong correlation between severe CF genotype in both alleles and pancreatic insufficient phenotype (P < 0.001).

CONCLUSIONS

Pancreatic exocrine insufficient CF patients could be differentiated from exocrine sufficient patients and HCs using short endoscopic secretin test.

Diagnosis of Exocrine Pancreatic Insufficiency

OPINION STATEMENT

The accurate diagnosis of exocrine pancreatic insufficiency (EPI) helps identify those in need of pancreatic enzyme replacement therapy. Conversely, ruling out EPI identifies those in which additional evaluation should be pursued to explain their symptoms. There are many available tests that can be used to diagnose EPI; however, the tests must be tailored to each clinical scenario. Tests that are convenient but less accurate (e.g., fecal elastase-1, qualitative fecal fat determination) are best suited for patients with a high pretest probability of EPI. In contrast, tests that are highly accurate but more cumbersome (e.g., endoscopic pancreatic function testing, 72-h fecal fat collection) are favored in patients suspected to have mild EPI or an early stage of chronic pancreatitis. Additional research is needed to identify a more convenient means of accurately diagnosing at all stages of EPI.

Approach to patients with suspected chronic pancreatitis: a comprehensive review

Chronic pancreatitis (CP) represents a significant health care burden in the United States. Diagnosing it early and accurately is important for the efficient management of these patients. However, the early diagnosis of CP, when structural and functional pancreatic changes are subtle, remains difficult. Complicating this is the large cohort of patients with nonspecific abdominal pain who are often suspected of having early CP and who utilize significant health care resources in attempts at diagnosis and management. We present a review of the current diagnostic tests available for making an early diagnosis of CP. We further report our approach to patients suspected of having CP based on the available literature.

Quantification of pancreatic function using a clinically feasible short endoscopic secretin test

OBJECTIVES

Clinical and morphological criteria are not precise enough to diagnose early chronic pancreatitis (CP). We investigated if short endoscopic pancreas function testing as a part of routine upper endoscopy could improve clinical diagnostics.

METHODS

Patients with suspected CP underwent modified secretin-stimulated upper endoscopy (short endoscopic secretin test, or EST). Duodenal juice was collected during 15 minutes starting 30 minutes after stimulation. A modified scoring system for CP after Layer with bicarbonate and fecal elastase 1 (FE1) was used. We tested with receiver operating characteristic curves the diagnostic accuracy of bicarbonate and FE1 and with analysis of variance how precise the 2 parameters can discriminate the groups.

RESULTS

Fifty-two patients aged 19 to 67 years and 25 healthy controls aged 19 to 64 years were included. Twenty-four patients fulfilled the modified Layer Score for CP or non-CP. The overall accuracy of the EST versus FE1 test was 85%/71%, with positive and negative predictive values of 100%/79% and 80%/69%, respectively.

CONCLUSIONS

Short EST is rapid and easy to perform and can be incorporated in daily routines. We demonstrate that EST is superior to FE1 in the assessment of pancreatic insufficiency and may prove to be useful in diagnosing early or mild CP.

Abnormal duodenal [HCO3-] following secretin stimulation develops sooner than endocrine insufficiency in minimal change chronic pancreatitis

OBJECTIVES

Direct pancreatic function tests (PFTs) are often used to diagnose chronic pancreatitis (CP). We aimed to determine the temporal relationship between an abnormal PFT result, cross-sectional imaging, and clinical symptoms.

METHODS

All patients referred for endoscopic ultrasound (EUS) and PFT for suspected CP at our medical center from 2008 to 2010 were included. Each subject underwent EUS and PFT on the same day using secretin stimulation.

RESULTS

Seventeen patients had duodenal HCO3 values of less than 80 mEq/L and were labeled as abnormal; the 25 other patients had at least 1 duodenal HCO3 values of 80 mEq/L or greater. Patients with abnormal PFTs had more parenchymal (2.0 vs 0.92, P = 0.012), ductal (1.18 vs 0.6, P = 0.036), and total features (3.18 vs 1.52, P = 0.009) than those with normal PFTs on EUS examination. There was no difference in regard to the frequency of abnormal CT scans (25% vs 15%, P = 0.139), diarrhea (67% vs 60%, P = 0.463), fat-soluble vitamin deficiency (33% vs 26%, P = 0.315), or diabetes (10% vs 4%, P = 0.066).

CONCLUSIONS

Patients with equivocal imaging and abnormally low duodenal HCO3 have more EUS features of CP than do patients with normal duodenal HCO3 values, suggesting that low duodenal HCO3 values are among the first measurable abnormalities in CP.

Endoscopic pancreatic function test using combined secretin and cholecystokinin stimulation for the evaluation of chronic pancreatitis

BACKGROUND

Current endoscopic pancreatic function test (ePFT) methods use either secretin or cholecystokinin (CCK) to measure pancreatic function.

OBJECTIVE

To evaluate a novel ePFT protocol that includes both secretin and CCK stimulation and to assess which fluid parameters best discriminate patients with chronic pancreatitis (CP).

DESIGN

Prospective, cross-sectional diagnostic study.

SETTING

Single, tertiary-care institution.

PATIENTS

Healthy volunteers and patients evaluated for CP were included.

INTERVENTIONS

All patients underwent a combined secretin-CCK ePFT. Patients evaluated for CP also underwent EUS during the same endoscopic session.

MAIN OUTCOME MEASUREMENTS

Duodenal fluid bicarbonate, lipase, and amylase concentrations were measured after CCK and secretin stimulation. Results were compared based on the presence of CP detected by EUS (≥5 features).

RESULTS

Twenty healthy volunteers and 69 patients evaluated for CP completed the secretin and CCK ePFT. Patients with an EUS score of 5 or higher had significantly decreased peak bicarbonate concentrations (72 mmol) compared with patients with an EUS score lower than 5 (90 mmol) and healthy subjects (108 mmol) (P < .001). Peak concentrations of amylase and lipase and total fluid volume were not significantly different between patients with CP and controls. Receiver-operating characteristic analysis revealed that peak bicarbonate concentration had superior discrimination for CP (area under the curve [AUC] 0.738) compared with peak amylase (AUC 0.677) and peak lipase (AUC 0.627). The addition of enzyme concentration measurement did not improve discrimination compared with peak bicarbonate alone.

LIMITATIONS

Secretin and cholecystokinin endoscopic pancreatic function test (SC ePFT) results were not compared with those of single hormone ePFTs.

CONCLUSIONS

The addition of CCK infusion and enzyme concentration measurement to a standard secretin ePFT does not enhance the diagnosis of CP.

Pancreatic duct compliance after secretin stimulation: a novel endoscopic ultrasound diagnostic tool for chronic pancreatitis

OBJECTIVES

Endoscopic ultrasound (EUS) evaluation of pancreatic duct compliance after secretin stimulation (sEUS) along with EUS morphologic examination (EUS) and duodenal fluid [HCO3] measurement (endoscopic pancreatic function test, ePFT) in 1 endoscopic session has not been reported as a means of evaluating for chronic pancreatitis (CP). We evaluated the feasibility of the combined examination and compared EUS measurements of pancreatic ductal compliance with duodenal fluid [HCO3] for diagnosing CP.

METHODS

The study is a prospective case series of patients with suspected CP who underwent a combined EUS, sEUS, and ePFT examination in 1 endoscopic session. The main outcome measures were the feasibility of performing the combination examination and the correlation between ductal compliance and ePFT.

RESULTS

All examinations were completed in 1 endoscopic session, and there were no complications in 35 patients. Although there was a trend toward less change from baseline head and body ductal diameter in patients with CP, only the percent change from baseline in the tail was significant (CP 144.3% vs healthy patients 240.9%, P < 0.01). Regression analysis demonstrated fair correlation between maximum change in ductal diameter and duodenal fluid [HCO3] (r = 0.27).

CONCLUSIONS

Combined EUS, sEUS, and ePFTs are feasible and safe, with preliminary results demonstrating a positive correlation between pancreatic ductal compliance and duodenal fluid [HCO3].

Secretin-enhanced MRCP: review of technique and application with proposal for quantification of exocrine function

OBJECTIVE

The purpose of this article is to present a proposal for quantification of exocrine function using secretin-enhanced MRCP for the diagnosis of chronic pancreatitis. The article also reviews the technique and application of secretin-enhanced MRCP in evaluating various pancreatic abnormalities.

SUBJECTS AND METHODS

One hundred thirty-four consecutive patients with chronic abdominal pain undergoing secretin-enhanced MRCP for suspected chronic pancreatitis were included. Patients were divided into four clinical groups (normal, equivocal, early chronic pancreatitis, established pancreatitis) on the basis of clinical symptoms and additional investigations, including CT (n=98), endoscopic pancreatic function test (n=65), endoscopic ultrasound (n=84), and ERCP (n=36). The volume of secretion was obtained by drawing a region of interest around T2 bright fluid secreted on postsecretin HASTE images. The maximal rate of secretion in response to secretin was obtained by plotting change in signal intensity on sequential postsecretin images. The analysis of variance test was used to compare the clinical groups with the volume and rate of secretion.

RESULTS

Significant volume differences were found between the normal and established pancreatitis groups (p<0.0001) as well as the equivocal and established pancreatitis groups (p<0.0005). Marginally significant differences were found between the normal and early pancreatitis groups (p=0.0150) as well as early and established pancreatitis groups (p=0.0351). Differences in the maximal rate of secretion were not statistically significant.

CONCLUSION

Secretory volume measurement of secretin-enhanced MRCP data is a simple method that brings out significant differences between normal, early, and established pancreatitis patients.

Update on endoscopic pancreatic function testing

Hormone-stimulated pancreatic function tests (PFTs) are considered the gold standard for measuring pancreatic exocrine function. PFTs involve the administration of intravenous secretin or cholecystokinin, followed by collection and analysis of pancreatic secretions. Because exocrine function may decline in the earliest phase of pancreatic fibrosis, PFTs are considered accurate for diagnosing chronic pancreatitis. Unfortunately, these potentially valuable tests are infrequently performed except at specialized centers, because they are time consuming and complicated. To overcome these limitations, endoscopic PFT methods have been developed which include aspiration of pancreatic secretions through the suction channel of the endoscope. The secretin endoscopic pancreatic function test (ePFT) involves collection of duodenal aspirates at 15, 30, 45 and 60 min after secretin stimulation. A bicarbonate concentration greater than 80 mmol/L in any of the samples is considered a normal result. The secretin ePFT has demonstrated good sensitivity and specificity compared with various reference standards, including the "Dreiling tube" secretin PFT, endoscopic ultrasound, and surgical histology. Furthermore, a standard autoanalyzer can be used for bicarbonate analysis, which allows the secretin ePFT to be performed at any hospital. The secretin ePFT may complement imaging tests like endoscopic ultrasound (EUS) in the diagnosis of early chronic pancreatitis. This paper will review the literature validating the use of ePFT in the diagnosis of exocrine insufficiency and chronic pancreatitis. Newer developments will also be discussed, including the feasibility of combined EUS/ePFT, the use of cholecystokinin alone or in combination with secretin, and the discovery of new protein and lipid pancreatic juice biomarkers which may complement traditional fluid analysis.

An automated analyzer provides clinically concordant results to manual back titration for quantitation of bicarbonate in pancreatic juice

OBJECTIVES

Secretin pancreatic function tests play an important role in the diagnosis of chronic pancreatitis. Back titration is the standard method for measurement of bicarbonate in pancreatic juice but is time consuming and manually performed. Use of an autoanalyzer for this purpose is not validated.

METHODS

Bicarbonate concentrations in secretin-stimulated pancreatic juice specimens were quantitated by manual back titration, a clinical chemistry autoanalyzer (automated bicarbonate, Roche Cobas c501, Roche Diagnostics, Indianapolis, Ind), and a blood gas analyzer (calculated bicarbonate, GEM 3000, Instrumentation Laboratories, Bedford, Mass). Kappa statistic analysis, Bland-Altman analysis, and Lin concordance correlation coefficients were calculated.

RESULTS

Ninety specimens from 31 subjects were included. Using a bicarbonate concentration of 80 mEq/L as a cutoff value, there was poor agreement between back titration and calculated bicarbonate (κ = 0.188); however, only 1 specimen showed discrepancy between back titration and automated bicarbonate (κ = 0.977). The limit of agreement between the back titration and automated bicarbonate was -9.0 to + 8.3 mEq/L. The Lin concordance correlation coefficient between the 2 methods was 0.931 (P < 0.001).

CONCLUSIONS

There is strong concordance between manual back titration and chemistry autoanalyzer methods for measurement of bicarbonate concentrations in pancreatic juice. Autoanalyzers may replace back titration for this purpose. Blood gas analyzers are unsuitable.

(13)C breath tests for the assessment of exocrine pancreatic function

The secretin-pancreozymin test is regarded as the most accurate of the pancreatic exocrine function tests but is cumbersome, time consuming, and invasive because it requires duodenal intubation and hormonal stimulation of the pancreas. Fecal analysis of fat, fecal elastase, or chymotrypsin are more practicable but far less sensitive to detect early stages of pancreatic exocrine insufficiency. Several (13)C-labeled substrates that are digested by pancreatic enzymes have been proposed for breath tests, thus assessing the intraluminal activity of pancreatic enzymes and therewith the pancreatic exocrine function. Particularly in pediatrics, (13)C breath tests are suited not only for diagnosis of pancreatic exocrine disorder, but also for therapy control under pancreatic enzyme substitution. However, the costs of substrates, the high time expenditure, and the lack of standardization still limit the clinical use of these breath tests. This review aims to place into perspective the traditional pancreatic exocrine function tests and the newer (13)C breath tests.

Combined endoscopic ultrasound and secretin endoscopic pancreatic function test in patients evaluated for chronic pancreatitis

BACKGROUND

Endoscopic ultrasound and endoscopic secretin pancreatic function test may be combined in a single endoscopic session (EUS/ePFT) to diagnose chronic pancreatitis (CP).

AIMS

Our primary aim was to assess the correlation and concordance of combined EUS and secretin ePFT bicarbonate results in suspected minimal change CP.

METHODS

Radial EUS included scoring for nine criteria (normal<4 criteria) with endoscopic collection of duodenal samples at 15, 30, and 45 min after secretin stimulation (normal peak bicarbonate>or=80 mmol/l).

RESULTS

Three hundred and two patients completed the EUS/ePFT (252 for suspected minimal change CP, 38 for established CP, 12 for painless steatorrhea). In patients evaluated for suspected minimal change CP, a moderate negative correlation was observed between endoscopic ultrasound score and peak bicarbonate (r=-0.38, P<0.001). The EUS and ePFT results were 76% concordant and 24% discordant. The ePFT was 85% sensitive and EUS was 100% sensitive for detecting patients with established calcific CP. The EUS/ePFT diagnosed CP in two of 12 of patients evaluated for painless steatorrhea or diarrhea with weight loss.

CONCLUSIONS

The combined EUS/ePFT is feasible and safe. There is only moderate correlation and concordance of endoscopic ultrasound and endoscopic pancreatic function test results in patients with suspected minimal change CP. The EUS and ePFT results produce complimentary functional and structural information for the evaluation of CP.

Evaluation of duct-cell and acinar-cell function and endosonographic abnormalities in patients with suspected chronic pancreatitis

BACKGROUND & AIMS

Endoscopic ultrasound (EUS) detects mild and severe structural abnormalities of the pancreas that correlate with fibrosis. Direct pancreatic function tests (PFTs) detect mild exocrine insufficiency associated with early fibrosis. The primary aim of this study was to compare EUS structural criteria with duct-cell and acinar-cell function.

METHODS

Fifty patients evaluated for chronic pancreatitis underwent combined EUS and secretin endoscopic PFTs (ePFT) on day 1 and CCK ePFT on day 2. EUS images were videotaped and interpreted by consensus of 3 blinded expert reviewers.

RESULTS

There were inverse correlations of EUS consensus score with both duct-cell bicarbonate secretion (R = -0.71, P < .001) and acinar-cell lipase secretion (R = -0.52, P < .001). With secretin ePFT as reference standard, EUS (>or=4 criteria) showed a sensitivity of 71% (95% confidence interval [CI], 53%-89%) and specificity of 92% (95% CI, 75%-99%). With CCK ePFT as reference standard, EUS had a sensitivity of 63% (95% CI, 43%-82%) and specificity of 85% (95% CI, 71%-98%). Main duct dilation, irregularity, calcifications, and visible side-branches were most predictive of exocrine insufficiency (positive predictive value >80% for both acinar- and duct-cell insufficiency).

CONCLUSIONS

Acinar- and duct-cell function decreases as EUS structural abnormalities increase. EUS has fair sensitivity and very good specificity compared with secretin and CCK functional reference standards.

Pancreatic function testing is best determined by the extended endoscopic collection technique

OBJECTIVE

To evaluate whether the extended secretin-stimulated direct endoscopic pancreatic function test (ePFT) technique is superior to the rapid 15 minute secretin-stimulated ePFT in determining pancreatic exocrine function.

METHODS

We conducted a retrospective study of 53 patients with chronic abdominal pain and normal pancreatic imaging. These patients had ePFT testing with the following modified endoscopic collection system. Porcine synthetic or human secretin was intravenously administered 15 minutes before endoscopic duodenal aspiration. The first 10-minute collection was performed in the third portion of the duodenum. A Liguory drainage tube was placed in the third portion of the duodenum. Two additional 10-minute-period collections were obtained via the drainage tube at 30 and 45 minutes after intravenous administration of secretin. All fluid collections were analyzed for bicarbonate (HCO3) concentration.

RESULTS

Peak HCO3 concentrations at 15 minutes occurred in 62%, at 30 to 40 minutes in 23%, and at 45 to 55 minutes in 15%. Normal concentrations of HCO3 (> or =80 mEq/L) were seen in 70%, abnormal concentration in 7%, and equivocal concentrations (60-79 mEq/L) in 23% even after 55 minutes of duodenal collections.

CONCLUSION

Collections beyond 15 minutes are necessary to improve accuracy of the ePFT in determining pancreatic exocrine function.

A rapid, endoscopic exocrine pancreatic function test and the Lundh test: a comparative study

BACKGROUND/AIMS

The diagnosis of chronic pancreatitis is often difficult in the early stages of the disease. Morphological tests may be normal, and reliable methods for the evaluation of the exocrine pancreatic function are time-consuming and troublesome. A new test for exocrine pancreatic function, using endoscopic aspiration of secretin-stimulated pancreatic juice, has been developed. We evaluated the test using the Lundh meal test as reference.

METHODS

The endoscopic secretin stimulation test (ESST) was performed in a consecutive row of 24 patients referred for pancreatic function testing because of clinical suspicion of chronic pancreatitis and in 23 healthy volunteers. The participants fasted overnight and secretin was given intravenously (1 CU/kg) as a bolus the following morning. Thirty minutes after administration of secretin, the tip of the duodenoscope was placed close to the ampulla of Vater and duodenal aspirate was drawn for 10 min. Intraduodenal concentrations of lipase, bicarbonate, elastase and zinc were measured. The concentration of lipase during the Lundh test (4 x 20 min aspiration) was used as reference test in the patients.

RESULTS

Judged from the Lundh test, the exocrine pancreatic function was nearly abolished in 5 patients (<10% of lower normal limit), reduced in 6 patients and normal in 13 patients. ESST failed in 1 patient (no aspirate). Lipase concentrations (KU/l) were significantly lower in the patients with nearly abolished function compared to patients with reduced or normal exocrine pancreatic function (NEPF; Mann-Whitney U test: p < 0.01), but an overlap was found between patients with reduced exocrine pancreatic function [100.1 (median); 60.0-225.0 (range)] patients with NEPF (145.7; 44.6-268.0) and healthy controls (175.0; 84.8-381.0). Bicarbonate concentrations (mEq/l) were significantly lower in patients with reduced exocrine pancreatic function (51.2; 32.5-69.6) compared to patients with NEPF (80.0; 48.1-101.8; Mann-Whitney U test: p < 0.05). Pancreatic elastase concentration was significantly lower in the group with nearly abolished exocrine function compared to patients with NEPF (Mann-Whitney U test: p < 0.05), but there was no difference between elastase concentrations among the other groups. We found significant correlation between lipase and bicarbonate concentrations during ESST and lipase concentrations during the Lundh test in all 23 patients (Spearman's Rank test: rho = 0.597 and 0.683, respectively, p < 0.01). By using receiver operating characteristic curves, best cut-off point for bicarbonate was estimated. Lipase and bicarbonate results in the healthy volunteers were not statistically different from results in patients with NEPF. No side effects were observed except for worsening of nausea and abdominal pain in 2 of the patients.

CONCLUSION

The ESST is safe, and by combining the estimation of lipase and bicarbonate concentrations this test is a rapid, easy and useful diagnostic test for exocrine pancreatic function.

Normal pancreatic exocrine function does not exclude MRI/MRCP chronic pancreatitis findings

OBJECTIVE

Abnormal pancreatic function tests have been reported to precede the imaging findings of chronic pancreatitis. Magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP) is increasingly accepted as the primary imaging modality for the detection of structural changes of early mild chronic pancreatitis. The aim of this study was to evaluate MRI/MRCP findings in patients with symptoms consistent with chronic pancreatitis who have normal Secretin Endoscopic Pancreatic Function test.

METHODS

A retrospective study of 32 patients referred for evaluation of chronic abdominal pain consistent with chronic pancreatitis and reported normal standard abdominal imaging (ultrasound, computed tomography, or MRI). All patients underwent Secretin Endoscopic Pancreatic Function testing and pancreatic MRI/MRCP at our institution. We reviewed the MRI/MRCP images in patients who had normal Secretin Endoscopic Pancreatic Function testing. MRI/MRCP images were assessed for pancreatic duct morphology, gland size, parenchymal signal and morphology, and arterial contrast enhancement.

RESULTS

Of the 32 patients, 23 had normal Secretin Endoscopic Pancreatic Function testing, and 8 of them had mild to marked spectrum of abnormal MRI/MRCP findings that were predominantly focal. Frequencies of the findings were as follows: pancreatic duct stricture (n=3), pancreatic duct dilatation (n=3), side branch ectasia (n=4), atrophy (n=5), decreased arterial enhancement (n=5), decreased parenchymal signal (n=1), and cavity formation (n=1). The remaining15 patients had normal pancreatic structure on MRI/MRCP.

CONCLUSIONS

Normal pancreatic function testing cannot exclude abnormal MRI/MRCP especially focal findings of chronic pancreatitis. Further studies needed to verify significance of these findings and establish MRI/MRCP imaging criteria for the diagnosis of chronic pancreatitis.

Pancreatic function testing: here to stay for the 21st century

The diagnosis of Chronic Pancreatitis (CP) is based on the detection of abnormal structure or function of the diseased pancreas. The pancreatic function tests more accurately determine the presence of CP than tests of structure, especially for early stage disease. The function tests can be divided into two categories: non-invasive and invasive. The invasive "tube" tests can reliably detect mild, early CP, but are only available at a few referral centers and tend to be poorly tolerated by patients. The non-invasive tests are easy to obtain, but tend to perform poorly in patients with early, mild disease. Therefore, no one test is useful in all clinical situations, and a detailed understanding of the rational, pathophysiologic basis, strengths, and limitations of various tests is needed. This review highlights the role of various pancreatic function tests in the diagnosis of CP including fecal fat analysis, fecal elastase, fecal chymotrypsin, serum trypsin, the secretin stimulation test, the cholecystokinin (CCK) stimulation test, the combined secretin-CCK stimulation test, the intraductal and endoscopic secretin stimulation tests, and the functional magnetic resonance imaging of the pancreas after secretin stimulation.

Comparison of endoscopic ultrasound and endoscopic retrograde pancreatography for the prediction of pancreatic exocrine insufficiency

Endoscopic retrograde pancreatography (ERP) is a sensitive test for the early ductal changes of chronic pancreatitis. More recently, endoscopic ultrasound (EUS) has also been proposed as a sensitive structural test for chronic pancreatitis. Few studies have compared EUS and ERP using an external reference standard. Direct pancreatic function tests (PFT) are an acceptable reference standard for chronic pancreatitis since they detect mild exocrine insufficiency. Our aim was to compare structural abnormalities as revealed by ERP and EUS for the prediction of exocrine insufficiency. Eight-three patients who underwent EUS, ERP, and secretin PFT for the evaluation of pancreatitis were identified from our database. Exocrine insufficiency was defined as a secretin PFT peak bicarbonate concentration <80 mEq/l. Based on the number of abnormal sonographic criteria observed, EUS findings were categorized as normal (<2 criteria), mild (3-5 criteria) or severe (6-9 criteria or calcifications). ERP findings were categorized based on the Cambridge classification. ERP and EUS did not differ significantly in either sensitivity (72% vs 68%, P = 0.52) or specificity (76% vs 79%, P = 0.40). ERP and EUS were similarly associated with exocrine insufficiency both in the presence of minimal (OR 3.4 and 4.9, respectively) and severe structural changes (OR 12 and 24, respectively). We consider EUS to have a diagnostic accuracy for the structural diagnosis of early- and late-stage chronic pancreatitis similar to that of ERP.

A prospective crossover study comparing secretin-stimulated endoscopic and Dreiling tube pancreatic function testing in patients evaluated for chronic pancreatitis

BACKGROUND

Direct pancreatic function tests (PFT) are conventionally performed with use of double-lumen "Dreiling" collection tubes. We have developed an endoscopic collection method (ePFT) that eases the performance of these tests.

OBJECTIVE

Our aim was to compare the bicarbonate results obtained from the secretin ePFT and Dreiling PFT methods in patients evaluated for chronic pancreatitis.

DESIGN

A prospective crossover design was used to compare the PFT methods.

SETTING

Tertiary care referral center.

PATIENTS AND INTERVENTIONS

Twenty-four patients undergoing an evaluation for chronic pancreatitis underwent the secretin-stimulated ePFT and Dreiling PFT methods on separate days.

MAIN OUTCOME MEASUREMENTS

Duodenal fluid bicarbonate concentrations and estimated bicarbonate outputs were compared.

RESULTS

The mean difference in peak bicarbonate concentration (Dreiling PFT minus ePFT) was 7 mEq/L (SD 20) and not statistically significant (P = .11). A good correlation in peak bicarbonate concentrations (r = 0.74, 95% CI, 0.48-0.88) and estimated bicarbonate output (r = 0.78, 95% CI, 0.54-0.90) was observed between the two PFT methods.

LIMITATION

The sensitivities and specificities of the secretin ePFT and Dreiling PFT could not be compared because of the lack of a histologic gold standard.

CONCLUSION

The secretin ePFT yields results similar to those of the Dreiling PFT in patients evaluated for chronic pancreatitis.

Chronic pancreatitis

PURPOSE OF REVIEW

As in previous reviews in this journal, this review is focused on the most important new observations in chronic pancreatitis made in the past year and the beginning of this year.

RECENT FINDINGS

Important observations include the following: first, the natural history and course of chronic pancreatitis; second, that smoking enhances the risk of chronic pancreatitis; third, possible new function tests in combination with imaging procedures; fourth, the superiority of surgery compared with endotherapy for long-term pain relief; fifth, new insights in autoimmune pancreatitis.

SUMMARY

All in all, little progress has recently been made in the field of diagnosis and therapy of chronic pancreatitis. There are some studies in the field of endotherapy and autoimmune pancreatitis that are promising however.

The efficiency of endoscopic pancreatic function testing is optimized using duodenal aspirates at 30 and 45 minutes after intravenous secretin

OBJECTIVES

The endoscopic secretin test (ePFT) takes an hour to perform, limiting its practicality for routine use. We sought to determine which timed endoscopic collections best predict the peak bicarbonate concentration from full hour-long test.

METHODS

A cross-sectional study was performed of all ePFTs performed at our institution from 2000 to 2004. We compared 7 theoretical shortened tests [4-single collections (15, 30, 45, or 60 minutes after secretin) and 3-dual collections (15/30, 30/45, 45/60 minutes after secretin)] to the full test and to each other using multivariate linear and Deming regression models.

RESULTS

The bicarbonate results of 240 ePFTs were analyzed. The dual 30/45-minute collection was the optimal method based on the closest agreement with the full test (94%). Deming regression reveals the 30/45 estimate to be the best combination from an analytic perspective, owing to its lack of significant proportional bias and minimal constant bias (5.1 mEq/L) as compared to the reference test. Use of the 30/45 method with the adjusted cutpoint 75 mEq/L produces very good specificity (93%) for ruling in exocrine insufficiency.

CONCLUSIONS

A dual timed aspiration at 30 and 45 minutes can be used to screen for pancreatic exocrine insufficiency in patients with abdominal pain, simplifying the use of the ePFT in clinical practice.

Serial contrast-enhanced MRI of the pancreas: correlation with secretin-stimulated endoscopic pancreatic function test

RATIONALE AND OBJECTIVES

The purpose of this study was to determine the relationship between the pancreatic enhancement on serial contrast-enhanced MRI (CEMRI) and pancreatic exocrine function using the secretin-stimulated endoscopic pancreatic function test (ePFT).

MATERIALS AND METHODS

A total of 30 patients with clinical symptoms consistent with chronic pancreatitis underwent CEMRI of the abdomen and ePFT within a 1- to 4-week interval. CEMRI was performed in arterial, early venous, and late venous phases. Secretin ePFT was performed with the measurement of HCO(3) concentration from the duodenal aspirates after secretin stimulation. Contrast enhancement ratio of the arterial phase to early venous phase was measured on CEMRI (SIRa/SIRv). A three-point evaluation system was used for grading the HCO(3) concentration and the enhancement ratio on MRI. For the significance of correlation, kappa statistics was used. Sensitivity and specificity of CEMRI was determined for the diagnosis of early chronic pancreatitis accepting ePFT as a reference.

RESULTS

Twenty patients had identical scores on both secretin ePFT and CEMRI. Ten patients revealed discrepancy in scores. Kappa statistics revealed moderate agreement between MRI and ePFT (kappa = 0.44). Sensitivity and specificity values for the diagnosis of pancreatitis were 82% and 57%, respectively. Positive predictive value was 56%, and negative predictive value was 86%.

CONCLUSION

The results of our data indicate that serial CEMRI is an appropriate imaging technique to rule out early chronic pancreatitis. However, secretin-stimulated imaging or ePFT may still be needed for the definite diagnosis of pancreatic exocrine dysfunction.