Indirect pancreatic function tests in children

Coefficient of Fat Absorption to Measure the Efficacy of Pancreatic Enzyme Replacement Therapy in People With Cystic Fibrosis: Gold Standard or Coal Standard?

OBJECTIVES

We sought data on the validity, reliability, responsiveness, and feasibility of the coefficient of fat absorption (CFA) as a measure of pancreatic enzyme replacement therapy (PERT) efficacy in people with cystic fibrosis (pwCF) and reviewed the literature for alternative measures.

METHODS

We searched PubMed for the Medical Subject Heading cystic fibrosis and the key words cystic fibrosis, fat absorption, CFA, and fecal fat imbalance; historical articles; and citations in bibliographies.

RESULTS

The lower the CFA, the greater its variability; thus, it is less variable in healthy individuals who have higher CFA than pwCF. In addition, the test-retest values for CFA are more variable in pwCF than the general population. There is no correlation between CFA and body mass index or PERT dose but CFA is related to gastrointestinal signs and symptoms. Research-quality CFA studies are expensive, time consuming, and odious to pwCF and research staff. Sparse stool tests, breath tests, and blood tests of fat absorption have been studied as potential alternatives to CFA to measure PERT efficacy.

CONCLUSIONS

Based on the evidence, we conclude that CFA as a measure of the efficacy of PERT is more of a "coal standard" than a gold standard; developing suitable alternatives should be a priority.

Fecal Fat Concentration and Excretion in the First 2 Years of Life: a Cross-Sectional Study

OBJECTIVES

Data on pancreatic exocrine secretion in the youngest children are scarce. The aim of the study was to determine the range of normal values for fecal fat concentration (FFC) and fecal fat excretion (FFE) in infants and toddlers up to 2 years of age.

METHODS

A total of 160 subjects aged 1 to 24 months (8 groups of 20: aged 1-3, 4-6 months, etc) were included in the study. In all children, FFC (%) and FFE (g/day) were assessed in 3-day stool collection.

RESULTS

FFC correlated with age (r = -0.50, P < 0.0001). Of infants aged 1 to 3 months 65% had FFC higher than the <5% norm proposed for older children. The values of 90th/95th FFC percentile ranged from 9.7/13.0% at 1 month to 3.1/3.2% at 24 months. FFE did not differ between age groups. It was, however, higher than 4 and 3 g/day in 7.5% and 15.0% infants, respectively. The first detailed nomogram for the assessment of FFC and FFE in children aged 1 to 24 months was created.

CONCLUSIONS

Healthy infants may have higher FFC and FFE than older children. We provide reference values, which should allow for both precise and facile FFC and FFE interpretation in clinical practice.

Incomplete functional and morphological recovery after acute and acute recurrent pancreatitis in children

BACKGROUND AND AIM

There is lack of data on functional and morphological recovery after an attack of acute pancreatitis (AP) or acute recurrent pancreatitis (ARP) in children. This study aims to evaluate the functional impairment and morphological changes in the pancreas after recovery.

METHODS

All consecutive patients presenting with AP (n = 61) or ARP (n = 35), as per standard diagnostic criteria, were enrolled. After 2 months of pancreatitis, fecal elastase-1 (FE-1) (μg/g) and 2-h oral glucose tolerance test to calculate oral disposition index (DI_o ) (mmol/L) (β-cell function) were performed. Morphological changes were assessed by endoscopic ultrasound and transabdominal ultrasound. Patients with chronic pancreatitis (CP) (n = 27) and healthy children (HC) (n = 26) were included as controls for functional parameters.

RESULTS

At a median follow up of 12 (4-44) and 11 (2-108) months, 66.7% and 75.9% (P = 0.57) of AP and ARP demonstrated exocrine insufficiency (FE-1 < 200), respectively. Mean (SD) FE-1 was 183.64 ± 150.94 (AP), 135.70 ± 103.80 (ARP), 46.56 ± 30.20 (CP), and 240.00 ± 181.83 (HC) (P < 0.001; anova) (AP vs CP, ARP vs CP, and CP vs HC; P < 0.001). Prediabetes due to insulin resistance was seen in 16.6% and 22.6% (P = 0.56) of AP and ARP. Median (interquartile range) DI_o (mmol/L) was comparable between AP (4.20 [2.36, 8.3]) and HC (5.20 [2.89, 8.68]), but was low in ARP (2.97 [1.80, 5.12]), which was comparable with CP (1.91 [1.20, 2.83]). Endoscopic ultrasound demonstrated morphological changes in 25% and 37% (P = 0.34) of AP and ARP, respectively.

CONCLUSION

There was high frequency of biochemical evidence of exocrine insufficiency. β-Cell function (DI_o ) was preserved among AP but was poor in ARP. Nearly one-third showed morphological changes in imaging.

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.

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.

Pancreatic Enzyme Replacement Therapy in Children with Severe Acute Malnutrition: A Randomized Controlled Trial

OBJECTIVE

To assess the benefits of pancreatic enzyme replacement therapy (PERT) in children with complicated severe acute malnutrition.

STUDY DESIGN

We conducted a randomized, controlled trial in 90 children aged 6-60 months with complicated severe acute malnutrition at the Queen Elizabeth Central Hospital in Malawi. All children received standard care; the intervention group also received PERT for 28 days.

RESULTS

Children treated with PERT for 28 days did not gain more weight than controls (13.7 ± 9.0% in controls vs 15.3 ± 11.3% in PERT; P = .56). Exocrine pancreatic insufficiency was present in 83.1% of patients on admission and fecal elastase-1 levels increased during hospitalization mostly seen in children with nonedematous severe acute malnutrition (P <.01). Although the study was not powered to detect differences in mortality, mortality was significantly lower in the intervention group treated with pancreatic enzymes (18.6% vs 37.8%; P < .05). Children who died had low fecal fatty acid split ratios at admission. Exocrine pancreatic insufficiency was not improved by PERT, but children receiving PERT were more likely to be discharged with every passing day (P = .02) compared with controls.

CONCLUSIONS

PERT does not improve weight gain in severely malnourished children but does increase the rate of hospital discharge. Mortality was lower in patients on PERT, a finding that needs to be investigated in a larger cohort with stratification for edematous and nonedematous malnutrition. Mortality in severe acute malnutrition is associated with markers of poor digestive function.

TRIAL REGISTRATION

ISRCTN.com: 57423639.

Secretin-Enhanced Magnetic Resonance Cholangiopancreatography for Assessing Pancreatic Secretory Function in Children

OBJECTIVE

To assess the accuracy and interrater reproducibility of measurements of pancreatic secretory function by magnetic resonance cholangiopancreatography in response to secretin administration and to describe our experience using the technique to noninvasively assess pancreatic secretory function in a pediatric population.

STUDY DESIGN

In the accuracy study, phantoms with varying fluid volume (47-206 mL) were imaged using the clinical quantification sequence. Fluid volume was measured by image segmentation (ImageJ). Measurement accuracy was expressed in terms of error (absolute and percent) relative to known fluid volume. In the reproducibility study and clinical experience, 31 patients with suspected pancreatic disease underwent 33 secretin-enhanced magnetic resonance cholangiopancreatography exams. Two-dimensional T2-weighted, fat-saturated single shot fast spin echo sequences were acquired before and after secretin injection (0.2 µg/kg, max 16 µg). Secreted fluid volume (postsecretin minus presecretin) was independently measured by 2 blinded reviewers. Between reviewer measurement reproducibility was assessed based on correlation (Spearman) and bias (Bland-Altman analysis).

RESULTS

For the accuracy study, fluid volumes were measured with mean volume errors of -0.3 to +12.5 mL (percent error -0.03% to +9.0%). For the reproducibility study, the mean secreted fluid volumes measured by reviewer 1 and reviewer 2 were 79.1 ± 54.3 mL (range 5.5-215.4) and 77.2 ± 47.1 mL (range 6.7-198.1 mL), respectively. Measured secreted fluid volumes were very strongly correlated (r = 0.922) between reviewers with a bias of only 1.9 mL (95% limits of agreement -40.5 to 44.2).

CONCLUSIONS

Measurement of fluid volume by magnetic resonance imaging is highly accurate with <10% (<13 mL) error in measured volume. Measurements of pancreatic secreted fluid volume in response to secretin by magnetic resonance cholangiopancreatography are highly reproducible with a bias of <2 mL between reviewers.

Utility of Direct Pancreatic Function Testing in Children

OBJECTIVES

Exocrine pancreatic insufficiency (EPI) can have a significant impact on a child's growth and nutrition. Our aim was to evaluate the utility of direct endoscopic pancreatic function testing (ePFT) in pediatrics.

METHODS

A single-center retrospective chart review was performed of children who underwent ePFT from December 2007 through February 2015. Endoscopic pancreatic function testings were performed by 1 of 2 methods: (1) intravenous cholecystokinin, followed by the collection of a single duodenal aspirate at 10 minutes, or (2) intravenous cholecystokinin or secretin, followed by the collection of 3 duodenal aspirates at a 5, 10, and 15 minutes. Samples were tested for pH and enzyme activities.

RESULTS

A total of 508 ePFTs were performed (481 single-sample tests, 27 multiple-sample tests). Based on the multiple-sample group, enzyme levels for chymotrypsin, amylase, and lipase peaked at 5 minutes, followed by a decrease in activity over time. Exocrine pancreatic sufficiency was identified in 373 (73.4%) and EPI in 93 (18.3%). Exocrine pancreatic sufficiency analysis found all pancreatic enzyme activities significantly increase with age: trypsin, chymotrypsin, amylase, and lipase, (P < 0.05).

CONCLUSIONS

Endoscopic pancreatic function testing can be used in the evaluation of EPI in children. Normative data suggest that pancreatic enzyme activities mature with age.

Exocrine pancreatic function in children with Alagille syndrome

Alagille syndrome (AGS) is often associated with symptoms of maldigestion, such as steatorrhea, hypotrophy and growth retardation. Exocrine pancreatic insufficiency was proposed as the underlying cause. We aimed to assess the exocrine pancreatic function with the use of different methods in AGS patients. Concentrations of fecal elastase-1 (FE1) and fecal lipase (FL) activities were measured in 33 children with AGS. The C-mixed triglyceride breath test (MTBT) in a subgroup comprising 15 patients. In all patients studied, FE1 concentrations and FL activities were normal. Abnormal MTBT results were documented in 4 (26.7%) patients. The FE1 and FL levels in MTBT-positive and MTBT-negative children did not differ. The results of this research do not confirm the presence of exocrine pancreatic dysfunction in AGS patients. Routine screening for exocrine pancreatic insufficiency of this group of patients is not necessary.

Both Exocrine Pancreatic Insufficiency and Signs of Pancreatic Inflammation Are Prevalent in Children with Complicated Severe Acute Malnutrition: An Observational Study

OBJECTIVES

To assess whether pancreatic function is impaired in children with severe acute malnutrition, is different between edematous vs nonedematous malnutrition, and improves by nutritional rehabilitation.

STUDY DESIGN

We followed 89 children with severe acute malnutrition admitted to Queen Elizabeth Central Hospital in Blantyre, Malawi. Stool and blood samples were taken on admission and 3 days after initial stabilization to determine exocrine pancreatic function via fecal elastase-1 (FE-1) and serum trypsinogen and amylase levels.

RESULTS

A total of 33 children (37.1%) had nonedematous severe acute malnutrition, whereas 56 (62.9%) had edematous severe acute malnutrition. On admission, 92% of patients showed evidence of pancreatic insufficiency as measured by FE-1 <200 μg/g of stool. Patients with edematous severe acute malnutrition were more likely to have low FE-1 (98% vs 82.8%, P = .026). FE-1 levels remained low in these individuals throughout the assessment period. Serum trypsinogen was elevated (>57 ng/mL) in 28% and amylase in 21% (>110 U/L) of children, suggesting pancreatic inflammation.

CONCLUSION

Exocrine pancreatic insufficiency is prevalent in children with severe acute malnutrition and especially in children with edematous severe acute malnutrition. In addition, biochemical signs suggestive of pancreatitis are common in children with severe acute malnutrition. These results have implications for standard rehabilitation treatment of children with severe acute malnutrition who may benefit from pancreatic enzyme replacement therapy.

TRIAL REGISTRATION

ISRCTN.com: 13916953.

Pancreatic Elastase-1 Quick Test for rapid assessment of pancreatic status in cystic fibrosis patients

BACKGROUND

At present, fecal elastase-1 ELISA determination is the most sensitive and specific tubeless pancreatic function test available. However, the results are not available the same day in routine clinical practice. This prospective study aims at evaluating the sensitivity and specificity of the Elastase-1 Quick™ Test by comparing the results with the ELISA test.

METHODS

The study was composed of three groups: the screening-diagnosed cystic fibrosis (CF) patients (n=28), the screened, but non-CF subjects (n=36) and non-screened CF patients (n=62). Pancreatic status (normal vs abnormal) was evaluated using the Pancreas Elastase-1 Quick™ Test. Fecal elastase-1 concentration was determined with a commercially available ELISA kit, used as reference. The cut-off for abnormal results was set at <200μg/g of stool.

RESULTS

The Pancreatic Elastase-1 Quick Test™ showed the following sensitivities and specificities in the studied groups: 92.8% and 96.6% in all subjects, 90.5% and 100% in screening samples, and 92.8 and 90.5% in CF patients.

CONCLUSION

Pancreatic Elastase-1 Quick Test™ proves to be a rapid and reliable option to qualitatively evaluate pancreatic function for diagnostic purposes in a clinical setting of CF care.

Identification and frequencies of cystic fibrosis mutations in central Argentina

BACKGROUND

The Argentinian population is mainly of Caucasian origin, with a small contingent of indigenous descent. The aim of this study is to test the hypothesis that a panel of mutations designed for European countries is not optimal as a first-line molecular diagnosis for routine use in this country of mixed European origin.

METHODS

Phenotype analyses combined with a European screening panel of 71 mutations followed by Sanger sequencing and large rearrangement study, were used to characterize the identification and distribution of CFTR mutations in the Santa Fe province of Argentina.

RESULTS

Clinical review of 121 subjects suspected of CF during childhood led to selection of 83 unrelated patients. Thirty four different mutations, including two new ones, c.2554dupT and p.Leu49Pro, were detected. The total sensitivity was 91% (n = 151/166 alleles).

CONCLUSIONS

Frequencies of CFTR mutations in Argentinian populations differ from those of their European ancestry. A new first line panel of 21 CFTR mutations with a sensitivity of 84% is proposed for routine use in central Argentina.

Evidence for a Cystic Fibrosis Enteropathy

Background

Previous studies have suggested the existence of enteropathy in cystic fibrosis (CF), which may contribute to intestinal function impairment, a poor nutritional status and decline in lung function. This study evaluated enterocyte damage and intestinal inflammation in CF and studied its associations with nutritional status, CF-related morbidities such as impaired lung function and diabetes, and medication use.

Methods

Sixty-eight CF patients and 107 controls were studied. Levels of serum intestinal-fatty acid binding protein (I-FABP), a specific marker for enterocyte damage, were retrospectively determined. The faecal intestinal inflammation marker calprotectin was prospectively studied. Nutritional status, lung function (FEV1), exocrine pancreatic insufficiency (EPI), CF-related diabetes (CFRD) and use of proton pump inhibitors (PPI) were obtained from the medical charts.

Results

Serum I-FABP levels were elevated in CF patients as compared with controls (p<0.001), and correlated negatively with FEV1 predicted value in children (r-.734, p<0.05). Faecal calprotectin level was elevated in 93% of CF patients, and correlated negatively with FEV1 predicted value in adults (r-.484, p<0.05). No correlation was found between calprotectin levels in faeces and sputum. Faecal calprotectin level was significantly associated with the presence of CFRD, EPI, and PPI use.

Conclusion

This study demonstrated enterocyte damage and intestinal inflammation in CF patients, and provides evidence for an inverse correlation between enteropathy and lung function. The presented associations of enteropathy with important CF-related morbidities further emphasize the clinical relevance.

A review of pathophysiology and management of fetuses and neonates with meconium ileus for the pediatric surgeon

PURPOSE

Meconium ileus (MI) is the earliest clinical manifestation of cystic fibrosis (CF), occurring in up to 20% of patients with CF. Our aim was to review and integrate current knowledge about the diagnosis and management of fetuses and neonates with MI that may aid the pediatric surgeon in caring for these patients.

METHODS

We identified areas of interest including pathophysiology, prenatal diagnosis, nonoperative and operative management, postoperative management, and prognosis. We performed a Medline search using the search term meconium ileus for English language articles published in the last 20 years. We reviewed reference lists to identify other articles of historical significance.

RESULTS

Meconium ileus is primarily associated with CF transmembrane (conductance) regulator mutations F508del, G542X, W1282X, R553X, and G551D, and modifier genes have been found to explain approximately 17% of the phenotypic variability. Mouse, pig, and ferret models for CF demonstrate neonatal bowel obstruction mimicking MI. Sonographic findings of hyperechoic masses and dilated bowel in a high-risk fetus are suggestive of MI. Less than 7% of low-risk fetuses with hyperechoic bowel will have MI. Contemporary series of noninvasive management with Gastrografin enema report success rates of 36% to 39%, significantly lower than historical values. The optimal surgical technique remains controversial, although primary anastomosis results in surgical complication rates between 21% and 31%, higher than those noted with delayed anastomosis. Pulmonary function for patients with CF and MI at 15 and 25 years old is similar to those without MI, although height and weight percentiles may be lower.

CONCLUSIONS

This review for pediatric surgeons presents an examination of the literature and synthesizes current information about the pathophysiology, prenatal diagnosis, nonoperative and operative management, postoperative management, and prognosis of the patient with CF and MI.

Lactose malabsorption is a risk factor for decreased bone mineral density in pancreatic insufficient cystic fibrosis patients

As decreased bone mineral density (BMD) is a common problem in cystic fibrosis (CF) and milk products may have pivotal dietary role affecting BMD, we aimed to assess the potential influence of adult-type hypolactasia (ATH) and lactose malabsorption (LM) on BMD in adolescent and young adult patients. In 95 CF pancreatic-insufficient patients aged 10-25 years (without liver cirrhosis, steatosis and cholestasis, diabetes mellitus, systemic glucocorticoid therapy), lumbar BMD, the nutritional status, pulmonary function, vitamin D3 concentration, calcium intake and single-nucleotide polymorphism upstream of the lactase gene were assessed. In subjects with the -13910 C/C genotype predisposing to ATH, the presence of LM was determined with the use of a hydrogen-methane breath test (BT). BMD and calcium intake were significantly lower in patients with the C/C genotype (P<0.028 and P<0.043, respectively). The abnormal BMD was stated more frequently in patients with the C/C genotype (P<0.042) and with LM (P<0.007). BMD, daily calcium intake and serum vitamin D concentration were significantly lower in LM subjects than in the other patients (P<0.037, P<0.000004 and P<0.0038, respectively). In logistic regression analysis, the relationship between examined parameters and BMD, was found to be statistically significant (P<0.001). However, only standardized body weight and LM were documented to influence BMD (P<0.025 and P<0.044, respectively). In conclusion, LM seems to be an independent risk factor for decreased BMD in CF patients.

Comparison of fecal elastase-1 and pancreatic function testing in children

OBJECTIVES

The fecal pancreatic elastase-1 (FE-1) test is considered a simple, noninvasive, indirect measure of pancreatic function. We aimed to evaluate the performance of the FE-1 test compared with the direct pancreatic function test (PFT) with secretin stimulation in children.

METHODS

Data of 70 children (6 months-17 years of age) who had both FE-1 test and PFT were analyzed.

RESULTS

The average FE-1 concentration was 403 ± 142 μg/g. Eleven children had concentrations below 200  μg/g, 23 between 201 to 500 μg/g, and 36 were above 500 μg/g. The average pancreatic elastase activity measured on direct stimulation was 49.1 ± 38.6  μmol · min (-1)· ml(-1) and 11 children had activity below the established cutoff (10.5 μmol · min(-1) · ml(-1)). Among the 11 children with pathologic PFT, 7 had normal FE-1, 4 were in the intermediate range (201-500 μg/g), and none were in the low range (<200 μg/g). Among the 59 children with normal direct PFT 11 (19%) had pathologic (<200 μg/g) and 19 (32%) had intermediate FE-1 tests. Twenty-nine children had both normal FE-1 concentration and normal PFT, giving a negative predictive value of 80%. The correlation between pancreatic elastase activity and FE-1 concentration was poor (r = 0.190). The sensitivity of the FE-1 test was found to be 41.7%, whereas the specificity was 49.2%. The positive predictive value of the FE-1 test was only 14%.

CONCLUSIONS

The FE-1 test is a simple, noninvasive, indirect method; however, ordering physicians should be aware of its limitations. It can give false-positive results and has low sensitivity in children with mild pancreatic insufficiency without cystic fibrosis and in those with isolated pancreatic enzyme deficiencies.

Adaptive changes of pancreatic protease secretion to a short-term vegan diet: influence of reduced intake and modification of protein

In our previous study, we demonstrated that abstaining from meat, for 1 month, by healthy omnivores (lacto-ovovegetarian model) resulted in a statistical decrease in pancreatic secretion as measured by faecal elastase-1 output. However, no correlation between relative and non-relative changes of energy and nutrient consumption and pancreatic secretion was documented. Therefore, in the present study, we aimed to assess the changes of exocrine pancreatic secretion with a more restrictive dietetic modification, by applying a vegan diet. A total of twenty-one healthy omnivores (sixteen females and five males) participated in the prospective study lasting for 6 weeks. The nutrient intake and faecal output of pancreatic enzymes (elastase-1, chymotrypsin and lipase) were assessed twice during the study. Each assessment period lasted for 7 d: the first before the transition to the vegan diet (omnivore diet) and the second during the last week of the study (vegan diet). The dietary modification resulted in a significant decrease in faecal elastase-1 (P < 0·05) and chymotrypsin output (P < 0·04). The lipase excretion remained unchanged. The decrease in proteolytic enzymes was documented to be positively correlated with a decreased protein intake (P < 0·05). In addition, elastase-1 and chymotrypsin outputs were also related to the changes of protein type, plantv.animal (P < 0·04 andP < 0·03, respectively). It was concluded that significant reduction and modification of protein intake due to a short-term vegan diet resulted in an adaptation of pancreatic protease secretion in healthy volunteers.

Mild CFTR mutations and genetic predisposition to lactase persistence in cystic fibrosis

Taking into account the reported incidence of hypolactasia in cystic fibrosis (CF) and the possible impact of milk products on nutritional status we aimed to assess the genetic predisposition to adult-type hypolactasia (ATH) and its incidence in CF. Single nucleotide polymorphism upstream of the lactase gene (LCT) was assessed in 289 CF patients. In subject with -13910C/C genotype (C/C) predisposing to ATH, hydrogen-methane breath test (BT) with lactose loading was conducted and clinical symptoms typical for lactose malabsorption were assessed. The percentage of CF patients with C/C was similar to that observed in healthy subjects (HS) (31.5 vs 32.5% ). Eleven out of 52 (24.5%) CF C/C patients had abnormal BT results. The recalculated frequency of lactose malabsorption was similar for the entire CF and HS populations (6.9 vs 7.2%). Similarly as in the control group, few CF patients have identified and linked to lactose consumption clinical symptoms. The frequency of LCT polymorphic variants in CF patients having and not having severe mutations of CFTR gene showed significant differences. The C allele was more frequent in homozygotes of the severe mutations than in patients carrying at least one mild/unknown mutation (P<0.0028) and in patients with at least one mild mutation (P < 0.0377). In conclusion, CF patients carrying mild CFTR mutations seem to have lower genetic predisposition to ATH. Lactose malabsorption due to ATH in CF is not more frequent than in the general population. Symptomatic assessment of lactose malabsorption in CF is not reliable.

Acid steatocrit determination is not helpful in cystic fibrosis patients without or with mild steatorrhea

BACKGROUND

Most methods used for the assessment of severe steatorrhea in cystic fibrosis (CF) are sensitive. In fact, the tests show their usefulness in a borderline zone of the results. Yet, the existing data related to acid steatocrit (AS) are still contradictory. Therefore, in the present study we have aimed to assess CF patients without or with mild steatorhea (<10 g/day) and evaluate the applicability of AS in such a subset of patients.

PATIENTS AND METHODS

In fifty-five CF patients, AS, fecal fat concentration (FFC) and fecal fat excretion (FFE) in 1-day stool collection were assessed from one to three times (149 samples). In 50 subjects, FFC, FFE, and AS were available for 3 subsequent days. It allowed for the calculations based upon 3-day fecal fat balance study.

RESULTS

The correlations between FFE/FFC and AS based upon 1-day stool collection, although statistically significant, were rather weak (r = 0.208, P < 0.011; r = 0.362, P < 0.000006, respectively). The correlations between FFE/FFC and AS based upon the 3-day stool collection, although stronger, did not show values a linear relationship (r = 0.394, P < 0.005; r = 0.454, P < 0.001, respectively). With no regard to the cut-off level for AS (10% and 20%), sensitivity, specificity, negative, and positive predictive values in the determination of abnormal FFC and FFE were not satisfactory. The flow charts describing the accuracy of AS to determine FFE and FC revealed a high level of uncertainty.

CONCLUSIONS

AS does not reflect in a reliable way FFE in CF patients without or mild steatorrhea. Its applicability in the assessment of FFC in such patients has therefore limited practical value.

Defining DIOS and constipation in cystic fibrosis with a multicentre study on the incidence, characteristics, and treatment of DIOS

OBJECTIVES

Various definitions for distal intestinal obstruction syndrome (DIOS), meconium ileus equivalent, and constipation in patients with cystic fibrosis (CF) are used. However, an unequivocal definition for DIOS, meconium ileus equivalent, and constipation is preferred. The aims of this study were, therefore, to seek consensus on the definitions for DIOS and constipation in patients with CF and to determine the incidence, characteristics, and treatment of DIOS in a cohort of paediatric patients with CF.

METHODS

During the 2005 European Society for Paediatric Gastroenterology, Hepatology, and Nutrition meeting in Porto a group of paediatric gastroenterologists discussed the definition of DIOS and constipation in CF. Subsequently, all patients younger than or equal to 18 years with complete DIOS according to the definition agreed upon and diagnosed during the years 2001 to 2005 in 8 CF centres were studied.

RESULTS

Distal intestinal obstruction syndrome was defined as an acute complete or incomplete faecal obstruction in the ileocaecum, whereas constipation was defined as gradual faecal impaction of the total colon. Fifty-one episodes of DIOS in 39 patients were recorded, giving an overall incidence of 6.2 (95% confidence interval, 4.4-7.9) episodes per 1000 patient-years. Of the 39 patients with DIOS, 20% experienced a relapse, 92% were pancreatic insufficient, 44% had a history of meconium ileus at birth, and 82% had a severe genotype. Conservative treatment was effective in 49 of 51 DIOS episodes (96%).

CONCLUSIONS

The European Society for Paediatric Gastroenterology, Hepatology, and Nutrition CF Working Group definitions of DIOS and constipation in CF are specific and make a clear distinction between these 2 entities. The incidence of DIOS in the present study was considerably higher than reported previously.

Constipation in pediatric cystic fibrosis patients: an underestimated medical condition

BACKGROUND

The aims of this study were to determine prevalence, risk factors and treatment of constipation in patients with Cystic Fibrosis (CF), as well as the diagnostic value of abdominal radiography.

METHODS

A cohort of 214 pediatric CF patients was investigated. Furthermore, 106 abdominal radiographs of CF patients with or without constipation were independently assessed by three observers on two separate occasions using the Barr and Leech scores.

RESULTS

The prevalence of constipation was 47%. Low total fat absorption and meconium ileus were independent risk factors for constipation in CF, while fiber and fluid intake were not associated. In CF patients the inter and intraobserver variabilities of the Barr and Leech scores were poor to moderate.

CONCLUSION

Constipation is a significant medical issue in CF and was associated with low total fat absorption and a history of meconium ileus. Finally, abdominal radiography seems of little value in the regular follow-up of CF patients.

Gastric acid inhibition for fat malabsorption or gastroesophageal reflux disease in cystic fibrosis: longitudinal effect on bacterial colonization and pulmonary function

OBJECTIVES

To investigate bacterial colonization and pulmonary function longitudinally in patients with cystic fibrosis (CF) receiving drugs for gastric acid (GA) inhibition for fat malabsorption or for gastroesophageal reflux disease (GERD).

STUDY DESIGN

A retrospective cohort study of 218 pediatric patients with CF was performed. Multilevel modeling was used to perform longitudinal analysis of forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), maximum expiratory flow at 50% of FVC (MEF(50)), and maximal mid-expiratory flow between 25% and 75% of FVC (MMEF(25-75)). Cox regression was used to calculate Pseudomonas aeruginosa- and Staphylococcus aureus-free survival.

RESULTS

Patients with CF and GA inhibition had a significantly smaller yearly decline of MEF(50) and MMEF(25-75) compared with control subjects. Other pulmonary function parameters and P aeruginosa or S aureus acquisition or colonization were not different from that of control subjects. GERD was associated with a significantly reduced pulmonary function (FEV(1) and FVC) and an earlier acquisition of P aeruginosa and S aureus.

CONCLUSIONS

GA inhibition did not affect pulmonary function or bacterial acquisition and therefore is not contraindicated in patients with CF. GA inhibition might improve pulmonary function with time, because the decline of MEF(50) and MMEF(25-75) was less pronounced. GERD was associated with a reduced pulmonary function and an earlier acquisition of P aeruginosa and S aureus. Therefore the diagnosis and treatment of GERD should be aggressively pursued in patients with CF.

Lack of correlation between fecal elastase-1 levels and fecal nitrogen excretion in preterm infants

We measured fecal elastase-1 (FE1) levels in 34 preterm newborns (15 small-for-gestational-age and 19 appropriate-for-gestational-age) during the first 2 months of life and evaluated whether they were correlated with nitrogen loss in stools. FE1 increased over time, and values were similar in both groups of newborns. Fecal nitrogen was significantly higher in small-for-gestational-age infants. There was no correlation between FE1 levels and fecal nitrogen excretion. Pancreatic proteolytic function was efficient at an early stage in enterally fed preterm newborns. Despite the similar FE1 values, fecal nitrogen loss was significantly higher in small-for-gestational-age preterm infants than in appropriate-for-gestational-age preterm infants.

The changing face of the exocrine pancreas in cystic fibrosis: pancreatic sufficiency, pancreatitis and genotype

(Table is included in full-text article.)Cystic fibrosis (CF) is the most frequent cause of exocrine pancreatic insufficiency in childhood. The cystic fibrosis transmembrane conductance regulator (CFTR) gene encodes CFTR protein that functions as cyclic AMP-dependent chloride channel allowing the passage of anions and secondarily water into the lumen of pancreatic ducts. Luminal chlorides are exchanged for bicarbonates. The lack of CFTR channel or its disrupted function (being the consequence of CFTR gene mutations) results in reduced volume of more acidic secretion. It has been suggested that such a situation leads to the precipitation of highly concentrated protein-containing secretion with obstruction and organ damage. The intensity of this process determines the progression of the disease. Steatorrhea is the significant symptom of classical form of CF. Residual pancreatic secretion in a subset of patients, however, allows for normal lipid digestion and absorption. Previous cross-sectional clinical studies estimated that about 85-90% of CF patients in preschool, school and older age are pancreatic insufficient. More frequent detection of mild and nonclassic forms of CF leads to higher frequency of pancreatic sufficiency (PS). The potential decline of exocrine pancreatic function, however, should be always considered. All PS patients with at least one severe or unknown CFTR mutation should be longitudinally assessed for the progression of pancreatic dysfunction. Recurrent acute and chronic pancreatitis is not a rare clinical condition in PS patients with PS: it might be the presenting symptom, even preceding CF diagnosis by several years. Potential appearance of this complication in individuals with pancreatic insufficiency demands elucidation.

The elimination of meat from the diet selectively decreases pancreatic elastase secretion

Since the vegetarian diet lacks the substrate for pancreatic elastase-1 as an enzyme, a decreased secretion of this enzyme could be expected. We aimed therefore to assess the changes of exocrine pancreatic secretion in a prospective way in a group of healthy omnivores who modified their diet by abstaining from meat for 1 month. Twenty healthy omnivores (fourteen females and six males) were used in the study. The nutrient intake was assessed for 7 d before commencing the study (omnivore diet) and after 1 month of dietary modification (modified diet; meat excluded). Similarly, the faecal output of pancreatic enzymes (elastase-1, chymotrypsin and lipase) was assessed before and 1 month after the period of dietary modification. Statistical differences between two points of the assessment (paired data) were calculated with the use of the Wilcoxon rank test. The relationship between the changes of faecal enzyme output and the changes in nutrient intake was assessed using multiple regression analysis. The dietary changes resulted in statistically significant decrease of faecal elastase-1 output (P < 0·05), whereas for chymotrypsin and lipase no changes were observed. No significant change in stool weight was recorded. No statistically significant correlation between changes in energy and nutrient consumption and changes in faecal output of pancreatic enzymes has been found. It was concluded that the exclusion of meat from the diet for a 1-month period results in significant changes in pancreatic secretion with a selective decrease of elastase-1 output. However, the underlying factor remains unclear.

Comparison of monoclonal and polyclonal ELISAs for fecal elastase in patients with cystic fibrosis and pancreatic insufficiency

OBJECTIVES

Two enzyme-linked immunosorbent assay methodologies are used to detect pancreatic insufficiency: monoclonal and polyclonal. We sought to compare these assays in patients with cystic fibrosis and to correlate these with the coefficient of fat absorption (CFA).

STUDY DESIGN

As part of a larger study, subjects had stool elastase measured by both methods while taking exogenous enzymes. Subjects subsequently stopped enzymes and had a fecal fat balance study performed; the CFA was then calculated.

RESULTS

One hundred twenty-four subjects participated in this substudy. The median values for the monoclonal and polyclonal assays were 0.3 and 22.75 microg/g, respectively. The correlation coefficient between the 2 tests was 0.86 (P < 0.0001). The correlation coefficients between CFA and the monoclonal and polyclonal assays were 0.24 (P = 0.006) and 0.10 (P = 0.27), respectively. If the criterion standard definition of pancreatic insufficiency was set at a CFA < 90% and the test definition of pancreatic insufficiency was set at <100 microg/g, then the monoclonal and polyclonal assay positive predictive values were 97.6% (120 of 123) and 97.4% (111 of 114), respectively.

CONCLUSIONS

The positive predictive value of both monoclonal and polyclonal fecal elastase in patients with cystic fibrosis is extremely good; however, correlation of either test with CFA was poor. The median value for the polyclonal elastase assay is higher than for the monoclonal assay, which could potentially lead to lower sensitivity of the polyclonal assay at lower cutpoints for the monoclonal assay is used.

Unresponsive or non-compliant steatorrhea in cystic fibrosis?

In 105 pancreatic insufficient CF patients (steatorrhea and low fecal elastase-1 concentrations), the effectiveness of pancreatic enzyme therapy (PET) has been assessed (fecal fat losses and coefficient of fat reabsorption). Eight unresponsive subjects were checked for PET compliance with fecal chymotrypsin assay. Three patients were documented to be non-compliant. Unresponsive patients should undergo evaluation for PET compliance.

Subclinical exocrine pancreatic dysfunction resulting from decreased cholecystokinin secretion in the presence of intestinal villous atrophy

The aim of this study was to evaluate the concept that pancreatic dysfunction in patients having gluten sensitivity (celiac disease [CD]) or cow's milk protein enteropathy (CMPE) may result from the lack of pancreatic enzyme stimulation in the absence or decrease of cholecystokinin (CCK) secretion caused by villous atrophy.

PATIENTS AND METHODS

The following parameters were measured: plasma CCK in response to a fatty meal and human pancreatic fecal elastase in 24 patients with CD while on gluten-free diet and after gluten provocation and in 12 patients with CMPE at diagnosis and after a 6-month period of cow's milk-free diet. Intestinal mucosa morphology was examined by small bowel biopsy. Sixty-three controls having no organic gastrointestinal problems were investigated once at the time of diagnostic evaluation.

RESULTS

Fasting CCK, obtained at a time when patients with CD or CMPE had normal intestinal mucosa, was significantly different from postprandial and comparable to that of the control group. Fasting CCK obtained from patients with villous atrophy was also statistically different, but not significantly, from the postprandial. Fasting and postprandial plasma CCK and fecal pancreatic elastase values from patients having normal intestinal mucosa were significantly higher than those obtained from patients with villous atrophy. Significant correlation of intestinal mucosa morphology and CCK with fecal elastase concentration was documented.

CONCLUSION

Exocrine pancreatic dysfunction in individuals having villous atrophy may be the consequence of decreased CCK secretion. Cholecystokinin and pancreatic secretion is restored to normal, with intestinal mucosa regeneration.

Fecal elastase-1: utility in pancreatic function in cystic fibrosis

Early detection and management of pancreatic insufficiency is essential to optimize health and outcomes in cystic fibrosis patients. The gold standard measures for assessment of pancreatic function are direct pancreatic stimulation tests, which have numerous limitations. Estimation of fecal elastase-1 level to determine pancreatic function is an attractive alternative as the test is simple, rapid, cost-effective and easy to perform even in children. This review summarizes the data from studies reflecting the validity, limitation and advantages of fecal elastase-1 in assessing pancreatic function in cystic fibrosis patients.

Exocrine pancreatic function in children with progressive familial intrahepatic cholestasis type 2

In progressive familial intrahepatic cholestasis type 2 (PFIC-2), severe steatorrhea is often documented. However, pancreatic exocrine secretion has not yet been studied. In 14 children with PFIC-2, pancreatic function was assessed using standard fecal tests. Normal fecal lipase concentrations excluded isolated lipase deficiency. No differences in fecal elastase-1 concentrations and chymotrypsin activities were detected between PFIC-2 patients with or without steatorrhea, nor between these patients and healthy subjects. In conclusion, pancreatic exocrine function in patients with PFIC-2 is normal. Steatorrhea observed in those patients is not related to pancreatic insufficiency.

Cystic fibrosis: nutritional consequences and management

Life expectancy for patients with Cystic Fibrosis (CF) has steadily improved during the last three decades, and death in childhood is now uncommon. Nutrition is a critical component of the management of CF, and nutritional status is directly associated with both pulmonary status and survival. Expert dietetic care is necessary, and attention must be given to ensuring an adequate energy intake in the face of demands which may be increased by inadequately controlled malabsorption, chronic broncho-pulmonary colonisation by bacteria and fungi, exacerbations of acute lung infection, impaired lung function, and the need for rehabilitation, repair and growth. Pancreatic enzyme replacement therapy (PERT) is needed by up to 90% of CF patients in Northern Europe, where the 'severe' mutation deltaF508 predominates, but a smaller proportion in Mediterranean countries and elsewhere, because pancreatic insufficiency is one of few features of CF which correlate with genotype. Complications of CF including liver disease and CF-related diabetes pose further challenges. In addition, deficiency of specific nutrients including fat soluble vitamins (particularly A, E and K) essential fatty acids and occasionally minerals occur for a variety of reasons. Osteopenia is common and poorly understood. Liver disease increases the likelihood of vitamin D deficiency. Glucose intolerance and diabetes affect at least 25% of CF adults, and the diabetes differs from both types 1 and 2 diabetes mellitus, but it inversely correlates with prognosis. Management consists of anticipating problems and addressing them vigorously as soon as they appear. Supplements of vitamins are routinely given. Energy supplements can be oral, enteral or, rarely, parenteral. All supplements, including PERT, are adjusted to individual needs.

Update on the evaluation of pancreatic exocrine status in cystic fibrosis

PURPOSE OF REVIEW

Pancreatic functional status has a very strong effect on outcome in cystic fibrosis and pancreatic insufficiency requires lifelong treatment with pancreatic enzymes. Traditionally, clinical signs and symptoms have been used to decide who should be treated with pancreatic enzyme supplements; however, recent studies show that patients with cystic fibrosis are both undertreated and over-treated using this approach. This paper reviews recent progress in the development of noninvasive, indirect tests of pancreatic function for use as diagnostic tools for patients with cystic fibrosis.

RECENT FINDINGS

Breath testing using C-labeled fat and measurement of several pancreatic enzymes in stool, such as chymotrypsin, lipase, and elastase have been explored as ways to define pancreatic functional status. Fecal elastase has good sensitivity, specificity, and positive and negative predictive value for defining severe pancreatic insufficiency in patients with cystic fibrosis and appears to be more useful than measurement of other fecal enzymes. Its role in milder pancreatic insufficiency and in disease states other than cystic fibrosis, such as chronic pancreatitis, is less clear.

SUMMARY

Several new noninvasive, indirect tests of pancreatic function have been developed to aid in the definition of pancreatic functional status in patients with cystic fibrosis. An objective measure of pancreatic functional status should be obtained in all patients with cystic fibrosis, and the recent development of new screening tools such as fecal elastase makes this feasible.