Plasma immunoreactive pancreatic cationic trypsinogen in cystic fibrosis: a sensitive indicator of exocrine pancreatic dysfunction

Low serum trypsinogen levels in chronic pancreatitis: Correlation with parenchymal loss, exocrine pancreatic insufficiency, and diabetes but not CT-based cambridge severity scores for fibrosis

BACKGROUND

Chronic pancreatitis (CP) is a complex inflammatory disorder of the pancreas affecting acinar cells, duct cells, islet cells and inflammatory cells including fibrosis-producing stellate cells. Serum trypsinogen is a biomarkers of acinar cell function.

AIM

To define the degree of correlation between low trypsinogen levels as a marker of acinar cell function and variable features of CP.

METHODS

Serum samples from previously ascertained and well phenotyped case and control subjects from the North American Pancreatitis Study II (NAPS2) were used to measure serum trypsinogen levels in a commercial laboratory. Control samples were used to define normal ranges and compared with levels in CP patients with defined features.

RESULTS

A final cohort of 279 CP patients and 262 controls from the NAPS2 studies were evaluated. In controls trypsinogen had a mean of 34.96 ng/ml and SD = 11.99. Cut-off values for low trypsinogen ranged from <20 to 10 ng/ml and very low trypsinogen at <10 ng/ml. Compared to controls, CP was associated with very low trypsinogen levels (p < 0.0001). Within CP, very low trypsinogen levels correlated with parenchymal loss (pancreatic surgery [p < 0.05]; atrophy with calcifications, [p < 0.001]), EPI (p < 0.01, trend p < 0.001) and diabetes (trend p < 0.01) but not CT-based criteria for fibrosis (pancreatic duct dilation, irregularity, strictures).

CONCLUSIONS

Very low serum trypsinogen levels correlate with measures of acinar cell loss including surgical resection, atrophic-calcific CP, diabetes and functional symptoms EPI but not duct morphology criteria. Serum trypsinogen levels correlate with decreased acinar cell function and therefore have biomarker utility clinical management.

Glucose homeostasis dependency on acini-islet-acinar (AIA) axis communication: a new possible pathophysiological hypothesis regarding diabetes mellitus

Studies have highlighted the existence of two intra-pancreatic axes of communication: one involved in the regulation of enzyme production by insulin-the insular-acinar axis; and another involved in the regulation of insulin release by pancreatic enzymes-the acini-insular axis. Previous studies by our laboratory show that pancreatic enzymes can affect blood glucose homeostasis and insulin secretion independently of their digestive functions, both from the gut lumen and probably from the blood. As a result we would like to introduce here the concept of acini-islet-acinar (AIA) axis communication (feedback), which could play an important role in the development of obesity and diabetes type 2. The AIA feedback links the endocrine and exocrine parts of the pancreas and emphasizes the essential role that the pancreas plays, as a single organ, in the regulation of glucose homeostasis by amylase most probably in gut epithelium and by insulin and glucagon in peripheral blood.

Cystic Fibrosis Foundation evidence-based guidelines for management of infants with cystic fibrosis

Newborn screening for cystic fibrosis (CF) offers the opportunity for early medical and nutritional intervention that can lead to improved outcomes. Management of the asymptomatic infant diagnosed with CF through newborn screening, prenatal diagnosis, or sibling screening is different from treatment of the symptomatically diagnosed individual. The focus of management is on maintaining health by preventing nutritional and respiratory complications. The CF Foundation convened a committee to develop recommendations based on a systematic review of the evidence and expert opinion. These guidelines encompass monitoring and treatment recommendations for infants diagnosed with CF and are intended to help guide families, primary care providers, and specialty care centers in the care of infants with CF.

Management of infants with cystic fibrosis: a summary of the evidence for the cystic fibrosis foundation working group on care of infants with cystic fibrosis

OBJECTIVE

To inform the development of Cystic Fibrosis (CF) Foundation guidelines on the care of infants with CF, we systematically reviewed the evidence for diagnosis and assessment of pancreatic and pulmonary disorders; management of pancreatic and pulmonary function; management of nutrition and nutritional disorders; and prevention and control of infections.

STUDY DESIGN

In May-June 2008, we searched The Cochrane Library for existing reviews; and MEDLINE, the National Guideline Clearinghouse, the CF Foundation Clinical Practice Guidelines and Consensus Statements, and the UK CF Trust for existing guidelines. MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and the Excerpta Medica Database (EMBASE) were searched for primary studies in January 2008. Bibliographies of eligible articles were searched and expert input was sought. We selected English-language articles of any study design that provided original data on any of our questions on infants up to 2 years of age.

RESULTS

We identified 14 relevant guidelines and 3 Cochrane reviews. Fifty-nine articles (55 primary studies) were included. Only four of these were randomized controlled trials. Sample sizes of infants ranged from 2 to 768 study participants; the median sample size was 24. Of our 21 review topics, 5 topics had only one study while for 5 we identified no relevant studies. We identified one or no primary studies for 20 of 32 review questions.

CONCLUSIONS

There is a paucity of evidence on the care of infants diagnosed with CF. For several of the review questions no guidelines or primary studies were identified, but for other questions, studies limited by weak design and small sample sizes were the only studies identified. With increasing numbers of infants with CF being diagnosed by newborn screening there is an opportunity to study the management of infants diagnosed with CF.

Usefulness of technetium-99m hexamethylpropylene amine oxime-labeled leukocyte scintigraphy to detect pancreatic necrosis in patients with acute pancreatitis. Prospective comparison with Ranson, Glasgow and APACHE-II scores and serum C-reactive protein

BACKGROUND

In acute pancreatitis (AP), pancreatic necrosis (PN) is an important local complication that can be identified by means of contrast-enhanced computed tomography (CECT). Pancreatic leukocyte infiltration is a significant pathogenic event in the development of PN that can be detected by labeled leukocyte scintigraphy (LLS). The aim of this study was to evaluate the utility of LLS with technetium-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO) to detect the presence of PN in patients with AP.

METHODS

Prospective cohort study of 84 patients with AP. Patients underwent LLS and the activity of images was scored on a 0-3 scale. CETC was performed to assess PN. Ranson, Glasgow and APACHE-II scores were calculated. Serum C-reactive protein (CRP) was measured. Sensitivity (Sn), specificity (Sp), positive predictive values (PPV), negative predictive values (NPV), areas under receiver operating characteristic (ROC) curves, likelihood ratios, odds ratios, analysis of variances between groups and correlation coefficients between tests were calculated.

RESULTS

PN was present in 11 (13%) patients. Pancreatic labeled leukocyte uptake was present in 38 patients (45%). Sn, Sp, PPV and NPV of LLS grade 2-3 for PN diagnosis were the highest (91, 88, 53 and 98%, respectively) of all tests. Patients with LLS grade 2-3 were 71 times more likely to be at risk of PN compared to those with LLS grade 0-1. The area under ROC curve of the LLS was the largest. A significant correlation was obtained between LLS and CRP (p < 0.001).

CONCLUSION

In patients with AP, LLS with (99m)Tc-HMPAO detects PN with an acceptable level of confidence and therefore could be considered an alternative technique to CECT in detecting PN.

Genetic and physiologic correlates of longitudinal immunoreactive trypsinogen decline in infants with cystic fibrosis identified through newborn screening

OBJECTIVES

To characterize the time course and physiologic significance of decline in serum immunoreactive trypsinogen (IRT) levels in infants with cystic fibrosis (CF) by mode of diagnosis and genotype, and to examine IRT heritability.

STUDY DESIGN

We studied longitudinal IRT measurements in 317 children with CF. We developed statistical models to describe IRT decline. Pancreatic disease severity (Mild or Severe) was assigned using CF genotype and was confirmed in 47 infants through fat malabsorption studies.

RESULTS

Infants with severe disease exhibited IRT decline with non-detectable levels typically seen by 5 years of age. Infants with mild disease exhibited a decline in the first 2 years, asymptomatically approaching a level greater than published norms. IRT and fecal fat were inversely correlated. IRT values in infants with meconium ileus (MI) were significantly lower than newborn-screened infants at birth. The high proportion of shared variation in predicted IRT values among sibling pairs with severe disease suggests that IRT is heritable.

CONCLUSIONS

IRT declines characteristically in infants with CF. Lower IRT values in newborns with MI suggest increased pancreatic injury. Furthermore, IRT is heritable among patients with severe disease suggesting genetic modifiers of early CF pancreatic injury. This study demonstrates heritability of a statistically modeled quantitative phenotype.

Exclusion of linkage of Shwachman-Diamond syndrome to chromosome regions 6q and 12q implicated by a de novo translocation

Shwachman-Diamond syndrome is a rare genetic disorder of unknown pathogenesis involving exocrine pancreatic insufficiency and hematological and skeletal abnormalities. There is broad clinical variability; the extent of heterogeneity is unknown but comparisons within a large cohort of patients show no striking differences between patients of families with single or multiple affected offspring. Segregation analysis of a cohort of 69 families has suggested an autosomal recessive mode of inheritance. A single constitutional de novo chromosome rearrangement was reported in a Japanese patient involving a balanced translocation, t(6;12)(q16.2;q21.2), thereby suggesting possible loci for a genetic defect. Evenly spaced microsatellite markers spanning 26-32 cM intervals from D6S1056 to D6S304 and D12S375 to D12S346 were analyzed for linkage in members of 13 Shwachman-Diamond syndrome families with two or three affected children. Two-point lod scores were calculated for each marker under assumptions of recessive inheritance and complete penetrance. Negative lod scores indicated exclusion of both chromosome regions. Further, affected sibs were discordant for inheritance of chromosomes in most families based on constructed haplotypes. The cytogenetic abnormality is not associated with most cases of Shwachman-Diamond syndrome.

Serum immunoreactive cationic trypsinogen: a useful indicator of severe exocrine dysfunction in the paediatric patient without cystic fibrosis

We evaluated serum cationic trypsinogen as a marker of exocrine pancreatic function in children without cystic fibrosis. The ability of this test to determine steatorrhoea of pancreatic origin, and its relationship to a wide range of exocrine pancreatic function were assessed. Serum trypsinogen was measured in 32 children with steatorrhoea, 10 with pancreatic and 22 with non-pancreatic causes. In patients with pancreatic steatorrhoea, serum cationic trypsinogen was 4.9 +/- 4.9 micrograms/l (mean +/- SD), significantly below values in patients with non-pancreatic steatorrhoea (47.0 +/- 22.1 micrograms/l, p less than 0.001) and 50 control subjects (31.4 +/- 7.4 micrograms/l, p less than 0.001). Serum cationic trypsinogen values in patients with pancreatic steatorrhoea all fell below the lower limit of our control range and below all values for patients with non-pancreatic steatorrhoea. Serum cationic trypsinogen was also evaluated against pancreatic trypsin output in 47 patients (range 0.2-17.0 yr who underwent a hormonal pancreatic stimulation test. In 17 patients, serum cationic trypsinogen was low (less than -2SD or less than 16.6 micrograms/l), and associated with greatly impaired pancreatic trypsin output, ranging from 0-8% of mean normal trypsin output. Five of these 17 patients did not have steatorrhoea. In 30 patients with normal or raised serum cationic trypsinogen (greater than or equal to 16.6 micrograms/l), pancreatic trypsin output ranged from 15-183% of mean normal values. In conclusion, low serum cationic trypsinogen suggests severely impaired exocrine pancreatic function, with sensitivity extending above the steatorrhoeic threshold. In the presence of steatorrhoea, low serum cationic trypsinogen indicates a pancreatic aetiology. Normal serum cationic trypsinogen, however, does not exclude impaired pancreatic function, above the steatorrhoeic threshold.

Abnormalities of circulating immunoreactive pancreatic anionic trypsinogen in cystic fibrosis: an assay artifact due to cross-reacting serum antibodies

In patients with CF, serum pancreatic cationic trypsinogen has proven to be useful for newborn diagnostic screening and also as a test of pancreatic function in the older patient. However, an assay for serum anionic trypsinogen is of no value as a test of pancreatic function in CF due to an apparent artifactual elevation of this enzyme in some patients. In this study, we evaluated the extent of the abnormality in the anionic trypsinogen assay and also elucidated the nature of the interfering material. CF patients were grouped according to the presence (pancreatic insufficiency) or absence (pancreatic sufficiency) of steatorrhea. In CF infants, both serum cationic and anionic trypsinogen levels were greatly elevated. Serum cationic trypsinogen declined with age in patients with pancreatic insufficiency, reaching low or undetectable levels after 6 years. In contrast, serum anionic trypsinogen levels remained normal or elevated in 33% of those over 6 years of age. There was no age-related change in either cationic or anionic trypsinogen among the CF patients with pancreatic sufficiency, and the majority had normal or elevated levels. Serum samples from selected CF patients were separated into IgG and non-IgG fractions using Staph. Protein A columns. Immunoreactive cationic and anionic trypsinogen were detectable in the non-IgG fractions of sera from CF infants and older patients with pancreatic sufficiency. In older CF patients with undetectable serum cationic and anionic trypsinogen, no immunoreactive material was detectable in either the IgG or non-IgG fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Age-related alterations in immunoreactive pancreatic lipase and cationic trypsinogen in young children with cystic fibrosis

Serum immunoreactive pancreatic lipase and cationic trypsinogen are elevated in young infants with cystic fibrosis (CF) and may be useful neonatal screening tests for CF. We compared lipase measured by a recently developed ELISA immunoassay with trypsinogen measured by radioimmunoassay in 70 children (ages 0.1 to 9.9 years) with CF who had various degrees of pancreatic dysfunction and in 79 similarly aged children without CF (controls). In the control children, lipase activity increased with advancing age, whereas trypsinogen showed no age-related trend. Lipase and trypsinogen were significantly elevated in the infants with CF who were younger than 1 year, irrespective of pancreatic function (trypsinogen, P less than 0.001; lipase, P less than 0.05). Sensitivities in detecting CF were 76% and 90% for lipase and trypsinogen, respectively. After the first year of life, lipase and trypsinogen values declined toward normal, the rate of decline of lipase being greater than that of trypsinogen; 67% of lipase values were within or below the normal range by 3 years, whereas 67% of trypsinogen values continued to be elevated. We conclude that trypsinogen is an excellent screening test for CF in young infants regardless of pancreatic function, and that the addition of a serum pancreatic lipase determination does not improve the accuracy of trypsinogen as a screening test for cystic fibrosis.

Serum immunoreactive trypsin and pancreatic lipase in cystic fibrosis

Serum immunoreactive trypsin (IRT) and pancreatic lipase have been measured in 59 patients with cystic fibrosis (age 1 month-27 years). Follow-up values were obtained from 49 patients. Their serum enzyme levels were compared to those of 120 healthy children of all age groups. Faecal fat excretion was determined in selected patients (n = 23) to elucidate the relationship between serum enzyme levels and pancreatic exocrine function. In cystic fibrosis IRT and lipase showed a very similar age-correlated pattern: in infancy levels were markedly elevated. During the following years the concentrations of both enzymes decreased rapidly and were found to be far below the normal range after the 10th year of life. Elevated enzyme levels in infancy as well as low levels in all age groups coincided with steatorrhea. Older patients (11-27 years) without severe pancreatic insufficiency however, had IRT and lipase levels in or above the normal range. In healthy children there was no age dependency of IRT levels, whereas in the first 12 months of life lipase levels were significantly lower than in later childhood.

Elevated serum immunoreactive pancreatic cationic trypsinogen in acute malnutrition: evidence of pancreatic damage

We used a sensitive probe of pancreatic dysfunction, serum immunoreactive cationic trypsinogen, to study 50 infants and children with varying degrees of malnutrition. Patients were classified into subgroups according to the severity of malnutrition. Mean serum trypsinogen concentration was significantly elevated in 25 patients with "severe" malnutrition (77.4 +/- 42.0 ng/ml, P less than 0.001) and in 23 with "moderate" malnutrition (55.2 +/- 16.1 ng/ml, P less than 0.02) compared with the mean value (32.5 +/- 10.4 ng/ml) for well-nourished controls. The level of circulating trypsinogen tended to rise with increasing severity of malnutrition. There was no relationship between serum trypsinogen and other variables such as age, specific diagnosis, or mode of feeling. Elevated serum trypsinogen levels could not be attributed to renal disease or cystic fibrosis. In patients who showed an improvement in nutritional status, serum trypsinogen tended to revert toward normal. Elevated serum trypsinogen values in acutely malnourished infants and children may result from pancreatic acinar cell damage or regurgitation of enzymes from obstructed pancreatic ducts.

Improved respiratory prognosis in patients with cystic fibrosis with normal fat absorption

The clinical presentation, courses, and sweat chloride values of 72 CF patients with normal fat absorption are described. In general, these patients had milder clinical symptoms and a lower mean sweat chloride value than their counterparts with steatorrhoea. Pulmonary function tests, including FEV1, FVC, FEF25%-75%, PaO2, and RV/TLC%, were significantly better in patients with normal fat absorption compared with both male and female patients who had steatorrhoea. The maintenance of better pulmonary function, coupled with the low mortality, suggests that patients without steatorrhoea have a better prognosis. This difference remains unexplained, but may be contributed to by nutritional, genetic, or pancreatic factors.