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

Exocrine Pancreatic Function in Girls with Anorexia Nervosa

OBJECTIVES

To assess pancreatic exocrine function in patients with anorexia nervosa using a breath test with 13C-labeled mixed triglycerides (MTG-BT) and to determine the relationship between the test results and selected biochemical and hormonal parameters.

MATERIAL AND METHODS

Anthropometric measurements, biochemical and hormonal parameters (serum leptin, soluble leptin receptor (sLR), acylated and desacylated ghrelin, free leptin index (FLI)), and MTG-BT were performed in a group of 31 girls with the restrictive type of AN, as well as 38 healthy girls (C).

RESULTS

The average cumulative dose of 13C-triglycerides recovered with exhaled air (%CD) was similar in both study groups, while the average time from 13C-triglycerides administration to peak 13CO2 excretion in expired air (time to peak (TTP)) was significantly longer in patients with AN compared to C. In both groups, %CD correlated negatively with FLI. TTP correlated negatively with sLR and FLI in the AN and with serum insulin and HOMA-IR values in the C.

CONCLUSIONS

In girls with AN, the pancreatic efficiency of lipase secretion was found to be normal, while the kinetics of this enzyme secretion were disturbed. These changes may result from disorders in the functioning of the adipose-insular and islet-acinar axes.

Synthesis of 13С- and 14С-labeled linoleic acids for use in diagnostic breath tests for hepatobiliary system disorders

At present, there is a need for a simple, noninvasive, highly specific and sensitive diagnostic test for hepatobiliary system disorders. Compounds labeled with carbon isotopes are widely used in various diagnostic breath tests; they are safe and can reliably detect a metabolic disorder or enzyme deficiency. The aim of this study was to synthesize 13С- and 14С-labeled linoleic acids suitable for use in hepatobiliary breath tests in terms of purity. In the synthesis of 13С-labeled linoleic acid, the chemical yield for 1-bromo-8,11-heptadecadien was 86.4% and the chemical yield for barium carbonate-13С, 96.0%. In the synthesis of 14С-labeled linoleic acid, the chemical yield for 1-bromo-8,11-heptadecadien was 87.39%; for barium carbonate-14С it was 97.1%. The specific radioactivity of 14С-labeled linoleic acids was 45.36 ± 0.02 mCi/g. The radiochemical yield of the reaction was 96.0%. The proposed method is suitable for batch production.

Chronic Pancreatitis: Current Status and Challenges for Prevention and Treatment

This paper reviews the current status of our understanding of the epidemiology, diagnosis, and management of the continuum of pancreatic diseases from acute and recurrent acute pancreatitis to chronic pancreatitis and the diseases that are often linked with pancreatitis including diabetes mellitus and pancreatic cancer. In addition to reviewing the current state of the field, we identify gaps in knowledge that are necessary to address to improve patient outcomes in these conditions.

Diagnosis of exocrine pancreatic insufficiency in chronic pancreatitis: 13C-Mixed Triglyceride Breath Test versus Fecal Elastase

BACKGROUND

Pancreatic enzyme replacement therapy (PERT) is indicated in case of clinically relevant exocrine pancreatic insufficiency (EPI). Clinical trials addressing PERT have used the coefficient of fat absorption (CFA) to define EPI but this test is cumbersome to perform. Our aim was to compare two easier-to-perform tests to detect clinically relevant EPI: Fecal Elastase-1 (FE-1) and ¹³C-Mixed Triglyceride Breath Test (TGBT).

METHODS

We prospectively included 54 patients with chronic pancreatitis (CP), 24.1% operated, 29.6% had EPI. EPI was defined as a CFA <93%. The sensitivity (Se), specificity (Sp), positive (PPV) and negative (NPV) predictive values for different cut-offs of FE-1 and TGBT were calculated.

RESULTS

The area under the ROC curve for FE-1/TGBT was 0.861/0.876 for the global sample, 0.842/0.794 for non-operated patients and 0.917/1 for operated patients respectively. Se, Sp, PPV and NPV for a cut-off of FE-1 <200 μg/g were 93.8%, 63.2%, 51.7% and 96% respectively. The best cut-off point for FE-1 was 84 μg/g, which yielded an 87.5% Se, 81.6% Sp, 66.7% PPV and 93.9% NPV. The same parameters for a TGBT <29% were 81.3%, 84.2%, 68.4% and 91.4% respectively. The best cut-off point for TGBT was <23%, which yielded an 81.3% Se, 94.7% Sp, 86.7% PPV and 92.3% NPV. Diabetes was associated to decreased FE-1 levels, even in multivariate analysis.

CONCLUSIONS

FE-1 and TGBT showed similar results for the diagnosis of EPI in CP. In non-operated CP patients, TGBT does not offer any advantage to FE-1 but in operated CP patients TGBT seems a more accurate test.

Supplementation of ursodeoxycholic acid improves fat digestion and absorption in cystic fibrosis patients with mild liver involvement

BACKGROUND

Ursodeoxycholic acid (UDCA) supplementation is recommended for cystic fibrosis (CF) patients with associated liver disease. However, its effect on fat digestion and absorption is not known.

MATERIALS AND METHODS

In 23 patients with mild liver involvement, a C-mixed triglyceride breath test was performed on UDCA supplementation (with and without pancreatic enzymes - standard and increased dose) and after 1 month of UDCA withdrawal. Cumulative percentage dose recovery [CPDR; median (interquartile range)] has been considered to reflect lipid digestion and absorption.

RESULTS

The enzyme supplementation resulted in a significant CPDR improvement [0% (0-0) vs. 4.6% (0.4-6.0); P<0.00046]. With the increased dose of enzymes in 16 patients with abnormal C-mixed triglyceride breath test results and lipase dose less than 3000 U/g of fat, higher CPDR values [8.6% (5.6-12.7); P<0.000027] were observed. However, a 1-month UDCA withdrawal resulted in a significant reduction in (P<0.000031) fat digestion and absorption [2.9% (0.7-5.8)].

CONCLUSION

UDCA supplementation seems to enhance lipid digestion and absorption in pancreatic insufficient CF patients with mild liver involvement. This finding points toward the potential impact of UDCA supplementation on nutritional status in CF patients with liver disease and underscores the often overlooked role of factors other than pancreatic enzymes on digestion and absorption of fats in CF.

(13)C-Breath testing in animals: theory, applications, and future directions

The carbon isotope values in the exhaled breath of an animal mirror the carbon isotope values of the metabolic fuels being oxidized. The measurement of stable carbon isotopes in carbon dioxide is called (13)C-breath testing and offers a minimally invasive method to study substrate oxidation in vivo. (13)C-breath testing has been broadly used to study human exercise, nutrition, and pathologies since the 1970s. Owing to reduced use of radioactive isotopes and the increased convenience and affordability of (13)C-analyzers, the past decade has witnessed a sharp increase in the use of breath testing throughout comparative physiology--especially to answer questions about how and when animals oxidize particular nutrients. Here, we review the practical aspects of (13)C-breath testing and identify the strengths and weaknesses of different methodological approaches including the use of natural abundance versus artificially-enriched (13)C tracers. We critically compare the information that can be obtained using different experimental protocols such as diet-switching versus fuel-switching. We also discuss several factors that should be considered when designing breath testing experiments including extrinsic versus intrinsic (13)C-labelling and different approaches to model nutrient oxidation. We use case studies to highlight the myriad applications of (13)C-breath testing in basic and clinical human studies as well as comparative studies of fuel use, energetics, and carbon turnover in multiple vertebrate and invertebrate groups. Lastly, we call for increased and rigorous use of (13)C-breath testing to explore a variety of new research areas and potentially answer long standing questions related to thermobiology, locomotion, and nutrition.

Effect of Critical Illness on Triglyceride Absorption

BACKGROUND

Adequate nutrition support for critically ill patients optimizes outcome, and enteral feeding is the preferred route of nutrition. Small intestinal glucose absorption is frequently impaired in critical illness. Despite lipid being a major constituent of liquid nutrient administered, there is little information about lipid absorption during critical illness.

OBJECTIVES

To determine small intestinal lipid, as well as glucose, absorption in critical illness compared with health.

MATERIALS AND METHODS

Twenty-nine mechanically ventilated critically ill patients and 16 healthy volunteers were studied. Liquid nutrient (60 mL, 1 kcal/mL), containing 200 µL (13)C-triolein and 3 g 3-O-methyl-glucose (3-OMG), was infused directly into the duodenum at a rate of 2 kcal/min. Exhaled (13)CO2 and serum 3-OMG concentrations were measured at timed intervals over 360 minutes. Lipid absorption was measured as the cumulative percentage dose (cPDR) of (13)CO2 recovered at 360 minutes. Glucose absorption was measured as the area under the 3-OMG concentration curve. Data are median (range) and analyzed using the Mann-Whitney U and Pearson correlation tests.

RESULTS

Lipid absorption was markedly less in the critically ill (cPDR(13)CO2: patients, 22.6% [0%-100%] vs healthy participants, 40.7% [5.3%-84.7%]; P = .018). While glucose absorption was less at 60 minutes in the critically ill (3-OMG60: 13.2 [3.5-29.5] vs 21.1 [9.3-31.9] mmol/L·min; P = .003), this was not apparent at 360 minutes (3-OMG360: 92.7 [54.5-147.9] vs 107.9 [64.0-168.7] mmol/L·min; P = .126). There was no relationship between lipid and glucose absorption.

CONCLUSION

Small intestinal absorption of lipid is diminished during critical illness.

Evaluation of Exalenz Bioscience's BreathID for Helicobacter pylori detection

Carbon-labeled urea breath tests, which have high sensitivity and specificity, are the preferred method used in epidemiological studies, screening dyspeptic patients and assessing eradication or recurrence of Helicobacter pylori infection. The principle of the (13)C-urea breath test relies upon the ability of the H. pylori urease to hydrolyze the orally administered (13)C-urea. The BreathID (Exalenz Bioscience Inc., Union, NJ, USA) provides a competitive solution for breath testing, including unique features such as automatic continuous breath collection and analysis. This is an unattended convenient test, with no human error as the correct part of the breath is collected and patients' assistance is not required. The test results are available in real time at the point of care and enable shortened breath testing procedures. Additionally, several studies showing expanded utility of the BreathID in pediatrics, after therapy and during proton pump inhibitors intake, further support the safety and performance of the BreathID in the diagnosis of H. pylori.

Gastro 2013 APDW/WCOG Shanghai working party report: chronic diarrhea: definition, classification, diagnosis

Diarrhea is best defined as passage of loose stools often with more frequent bowel movements. For clinical purposes, the Bristol Stool Form Scale works well to distinguish stool form and to identify loose stools. Laboratory testing of stool consistency has lagged behind. Acute diarrhea is likely to be due to infection and to be self-limited. As diarrhea becomes chronic, it is less likely to be due to infection; duration of 1 month seems to work well as a cut-off for chronic diarrhea, but detailed scientific knowledge is missing about the utility of this definition. In addition to duration of diarrhea, classifications by presenting scenario, by pathophysiology, and by stool characteristics (e.g. watery, fatty, or inflammatory) may help the canny clinician refine the differential diagnosis of chronic diarrhea. In this regard, a careful history remains the essential part of the evaluation of a patient with diarrhea. Imaging the intestine with endoscopy and radiographic techniques is useful, and biopsy of the small intestine and colon for histological assessment provides key diagnostic information. Endomicroscopy and molecular pathology are only now being explored for the diagnosis of chronic diarrhea. Interest in the microbiome of the gut is increasing; aside from a handful of well-described infections because of pathogens, little is known about alterations in the microbiome in chronic diarrhea. Serological tests have well-defined roles in the diagnosis of celiac disease but have less clearly defined application in autoimmune enteropathies and inflammatory bowel disease. Measurement of peptide hormones is of value in the diagnosis and management of endocrine tumors causing diarrhea, but these are so rare that these tests are of little value in screening because there will be many more false-positives than true-positive results. Chemical analysis of stools is of use in classifying chronic diarrhea and may limit the differential diagnosis that must be considered, but interpretation of the results is still evolving. Breath tests for assessment of carbohydrate malabsorption, small bowel bacterial overgrowth, and intestinal transit are fraught with technical limitations that decrease sensitivity and specificity. Likewise, tests of bile acid malabsorption have had limited utility beyond empirical trials of bile acid sequestrants.

Pancreatic enzyme therapy

BACKGROUND

Treatment with pancreatic enzymes must be based on an understanding of the normal physiology and pathophysiology of exocrine pancreatic function, as well as of the diseases that cause exocrine pancreatic insufficiency of either a structural or a functional type. These include chronic pancreatitis, pancreatic cancer, cystic fibrosis, pancreaticocibal asynchrony after gastric or pancreatic surgery, and celiac disease.

METHODS

Selective review of the literature.

RESULTS

Exocrine pancreatic insufficiency can cause meteorism, diarrhea, steatorrhea, and weight loss. All of these manifestations are non-specific except steatorrhea. Enzyme supplementation is indicated only for the treatment of demonstrated pancreatic dysfunction; unfortunately, however, no sensitive and specific pancreatic function tests are currently available. As a result, pancreatic enzyme supplementation is considered to be indicated on pragmatic grounds when, for example, the patient is suffering from diarrhea and weight loss and has been demonstrated to have a disease leading to exocrine pancreatic insufficiency. To be acceptable for clinical use, a pancreatin preparation must satisfy the following criteria: it must be enterically coated, so that it will not be destroyed by gastric acid; mix well with gastric chyme; exit the stomach simultaneously with chyme; and be rapidly released from its enteric coating upon entering the duodenum. Although there have been no large-scale, randomized comparative studies of different types of pancreatin preparation, the current clinical preference is for enterically coated micropellets or minitablets with a diameter of 2 mm or less. The initial dosage is 20 000 to 40 000 units of lipase taken once or twice per meal, with dose adjustment afterward as needed. The dose can be raised, and a proton-pump inhibitor can be added on.

CONCLUSION

There is still no simple test that can be used to diagnose pancreatic exocrine insufficiency with certainty. The treatment is symptomatic; its goals are to lessen steatorrhea and reverse weight loss.