New faecal tests in gastroenterology

Laboratory investigation of peritoneal fluids: an updated practical approach based on the available evidence

Even though analysis of peritoneal fluids (PF) is often requested to medical laboratories for biochemical and morphological tests, there is still no mutual agreement on what the most appropriate way is to manage PF samples and which tests should be appropriately executed. In this update, we tried to identify the most useful tests for PF analysis to establish best practice indications. We performed a literature review and examined available guidelines to select the most appropriate tests by an evidence-based approach. Accordingly, the basic PF profile should include (1) serum to effusion albumin gradient and (2) automated cell counts with differential analysis. This profile allows to determine the PF nature, differentiating between 'high-albumin gradient' and 'low-albumin gradient' effusions, which helps to identify the pathophysiological process causing the ascites formation. Restricted to specific clinical situations, additional tests can be requested as follows: PF lactate dehydrogenase (LDH) and glucose, to exclude (LDH) or confirm (glucose) secondary bacterial peritonitis; PF total protein, to differentiate ascites of cardiac origin from other causes; PF (pancreatic) amylase, for the identification of pancreatic ascites; PF bilirubin, when a choleperitoneum is suspected; PF triglycerides, in differentiating chylous from pseudochylous ascites and PF creatinine, to detect intraperitoneal urinary leakage.

Aziz SH, Zakaria Z, Wong MPK, Zakaria AD. The Use of M2-Pyruvate Kinase as a Stool Biomarker for Detection of Colorectal Cancer in Tertiary Teaching Hospital: A Comparative Study

Purpose

Guaiac fecal occult blood test (gFOBT) has been the standard for colorectal screening but it has low sensitivity and specificity. This study evaluated the use of fecal tumor M2-pyruvate kinase (M2-PK) for detection of colorectal cancer and to compare with the current surveillance tool; gFOBT in symptomatic adult subjects underwent colonoscopy.

Methods

Stool samples were collected prospectively from symptomatic adults who had elective colonoscopy from September 2014 to January 2016 and were analyzed with the ScheBo M2-PK Quick test and laboratory detection of fecal hemoglobin.

Results

The results were correlated to the colonoscopy findings and/or histopathology report. Eighty-five subjects (age of 56.8 ± 15.3 years [mean ± standard deviation]) were recruited with a total of 17 colorectal cancer (20.0%) and 10 colorectal adenoma patients (11.8%). The sensitivity of M2-PK test in colorectal cancer detection was higher than gFOBT (100% vs. 64.7%). M2-PK test had a lower specificity when compared to gFOBT (72.5% vs. 88.2%) in colorectal cancer detection. The positive and negative predictive values were 47.2% and 100% for M2-PK test and 57.9% and 90.9% for gFOBT.

Conclusion

Fecal M2-PK Quick test has a high sensitivity for detection of colorectal cancer when compared to gFOBT, making it the potential choice for colorectal tumor screening biomarker in the future.

Mass Spectrometry-Based Analysis for the Discovery and Validation of Potential Colorectal Cancer Stool Biomarkers

Colorectal cancer (CRC) is the third leading cause of cancer mortality for both men and women, and the second leading cause of cancer death for men and women combined. If detected early, before metastasis has occurred, survival following surgical resection of the tumor is >90%. Early detection is therefore critical for effective disease surveillance. Unfortunately, current biomarker assays lack the necessary sensitivity and specificity for reliable early disease detection. Development of new robust, non- or minimally invasive specific and sensitive biomarkers or panels with improved compliance and performance is therefore urgently required. The use of fecal samples offers several advantages over other clinical biospecimens (e.g., plasma or serum) as a source of CRC biomarkers, including: collection is noninvasive, the test can be performed at home, one is not sample limited, and the stool effectively samples the entire length of the inner bowel wall contents (including tumor) as it passes down the gastrointestinal tract. Recent advances in mass spectrometry now facilitate both the targeted discovery and validation of potential CRC biomarkers. We describe, herein, detailed protocols that can be used to mine deeply into the fecal proteome to reveal candidate proteins, identify proteotypic/unitypic peptides (i.e., peptides found in only a single known human protein that serve to identify that protein) suitable for sensitive and specific quantitative multiplexed analysis, and undertake high-throughput analysis of clinical samples. Finally, we discuss future directions that may further position this technology to support the current switch in translation research toward personalized medicine.

Faecal calprotectin for differentiating between irritable bowel syndrome and inflammatory bowel disease: a useful screen in daily gastroenterology practice

OBJECTIVE

To determine the best faecal calprotectin (FCP) cut-off level for differentiating between irritable bowel syndrome (IBS) and organic disease, particularly inflammatory bowel disease (IBD), in patients presenting with chronic diarrhoea.

DESIGN

Retrospective analysis of patients who had colonoscopy, histology and FCP completed within 2 months.

SETTING

District general hospital.

PATIENTS

Consecutive new patients with chronic diarrhoea lasting longer than 4 weeks.

INTERVENTIONS

Patients were seen by a single experienced gastroenterologist and listed for colonoscopy with histology. Laboratory investigations included a single faecal specimen for calprotectin assay (lower limit of detection: 8 µg/g), the results used for information only.

MAIN OUTCOME MEASURES

Six FCP cut-off levels (range 8-150 µg/g) were compared against the 'gold standard' of histology: inflammation 'present' or 'absent'.

RESULTS

Of 119 patients studied, 98 had normal colonoscopy and histology. The sensitivity of FCP to detect IBD at cut-off levels 8, 25 and 50 µg/g was 100% (with corresponding specificity 51%, 51%, 60%). In contrast, the lowest FCP cut-off, 8 µg/g, had 100% sensitivity to detect colonic inflammation, irrespective of cause (with negative predictive value (NPV) 100%). Importantly, 50/119 patients (42%) with FCP <8 µg/g had normal colonoscopy and histology.

CONCLUSIONS

Our results suggest that using FCP to screen patients newly referred for chronic diarrhoea could exclude all without IBD and, at a lower cut-off, all without colonic inflammation, thus avoiding the need for colonoscopy. Such a major reduction has implications for resource allocation.

Comparison of two immunoassays for measurement of faecal calprotectin in detection of inflammatory bowel disease: (pre)-analytical and diagnostic performance characteristics

BACKGROUND

Symptoms of inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) can overlap. Faecal calprotectin has recently been established to be a non-invasive marker for neutrophilic intestinal inflammation. We compared two devices for extraction of faecal calprotectin. Based on these results, two immunoassays for measurement of faecal calprotectin were evaluated.

METHODS

Samples were extracted using the Thermo Fisher extraction device (Thermo Fisher Scientific) and Smart Pep extraction device (Roche Diagnostics) and measured with the EliA Calprotectin immunoassay (Thermo Fisher Scientific) on ImmunoCAP 250. The performance of both assays was investigated by enrolling 183 consecutive patients (79 males, 104 females; median age 32 years) with clinical suspicion of IBD. Faecal calprotectin was measured using a recently launched immunoassay, EliA Calprotectin in comparison with an established immunochomatographic point-of-care-test (POCT, Quantum Blue Calprotectin; Bühlmann). Results were compared with endoscopic and histological findings.

RESULTS

The use of the Thermo Fisher extraction device resulted in an underestimation of faecal calprotectin concentrations, especially in liquid stool samples. IBD was diagnosed in 51/183 patients (27.9%) [Crohn's disease (CD, n=37), ulcerative colitis (UC, n=14)]. After adjusting the optimal cut-off for detection of IBD using receiver operating curve analysis, a sensitivity of 94.1% and 90.2% and specificity of 87.9% and 90.9% for the EliA and POCT assay, respectively, were obtained.

CONCLUSIONS

The Thermo Fisher device is not reliable for extraction of faecal calprotectin. The performance characteristics of the EliA Calprotectin assay are statistically equivalent to the Bühlmann POCT.

Novel Testing Enhances Irritable Bowel Syndrome Medical Management: The IMMINENT Study

Primary Study Objective:

To evaluate the economic utility of a fecal biomarker panel structured to suggest alternative, treatable diagnoses in patients with symptoms of irritable bowel syndrome (IBS) by quantifying, comparing, and contrasting health service costs between tested and non-tested patients.

Study Design:

Retrospective, matched cohort study comparing direct medical costs for IBS patients undergoing fecal biomarker testing with those of matched control subjects.

Methods:

We examined de-identified medical and pharmacy claims of a large American pharmacy benefit manager to identify plan members who underwent panel testing, were eligible for covered benefits for at least 180 days prior to the test date, and had data available for 30, 90, and 365 days after that date. We used propensity score matching to develop population-based control cohorts for each tested cohort, comprised of records with IBS-related diagnoses but for which panel testing was not performed. Primary outcome measures were diagnostic and medical services costs as determined from claims data.

Results:

Two hundred nine records from tested subjects met inclusion criteria. The only significant baseline differences between groups were laboratory costs, which were significantly higher in each tested cohort. At each follow-up time point, total medical and gastrointestinal procedural costs were significantly higher in non-tested cohorts. Within tested cohorts, costs declined significantly from baseline, while costs rose significantly in non-tested control cohorts; these differences were also significant between groups at each time point.

Conclusions:

Structured fecal biomarker panel testing was associated with significantly lower medical and gastrointestinal procedural costs in this study of patients with IBS symptoms.

Clinical significance of fecal lactoferrin in screening of colorectal carcinoma

AIM: To investigate the clinical significance of fecal lactoferrin in the screening of colorectal carcinoma (CRC).

METHODS: Thirty-five healthy people as controls, 63 patients with CRC, 59 patients with intestinal polyps, and 50 patients with functional gastroenteropathy were recruited. All of the patients were asked to collect 5-10 g fecal sample during three days after colonoscopy. Enzyme-linked immunosorbent assay was used to determine fecal lactoferrin level.

RESULTS: The median fecal lactoferrin levels in CRC patients, healthy people, patients with intestinal polyps and those with functional gastroenteropathy were 59.30, 2.94, 17.63 and 3.22 μg/g, respectively; there was no significant difference in fecal lactoferrin levels between patients with functional gastroenteropathy and healthy people (P > 0.05), but statistical significances were observed between patients with functional gastroenteropathy and those with CRC or intestinal polyps (P < 0.01), between healthy people and patients with CRC or intestinal polyps (P < 0.01), and between patients with CRC and those with intestinal polyps (P < 0.01). The sensitivity, specificity, accuracy, Youden index, positive likelihood ratio and negative likelihood ratio of fecal lactoferrin for screening of CRC were 88.9%, 85.7%, 87.8%, 0.75, 6.22 and 0.13, respectively.

CONCLUSION: Fecal lactoferrin detection is a simple, non-invasive method for screening CRC, with a high sensitivity and specificity.

Clinical utility of fecal biomarkers for the diagnosis and management of inflammatory bowel disease

Diagnosis and monitoring of inflammatory bowel diseases rely on clinical, endoscopic, and radiologic parameters. Inflammatory biomarkers have been investigated as a surrogate marker for endoscopic diagnosis of inflammatory activity. Fecal inflammatory biomarkers such as calprotectin and lactoferrin are direct products of bowel inflammation and provide an accurate and noninvasive diagnostic and monitoring modality for Crohn's disease and ulcerative colitis. This report contains an overview of the currently existing literature pertaining to clinical implications of fecal biomarkers for diagnosis, monitoring, and prediction of outcomes of inflammatory bowel disease.

Evaluation of specific fecal protein biochips for the diagnosis of colorectal cancer

AIM: To develop and initially test a potential fecal protein biochip for the screening of colorectal cancer (CRC).

METHODS: Fecal protein from 20 colorectal cancer patients and 20 healthy controls were extracted from all of the fecal samples and screened for proteomic differences using a Biotin label-based protein array. Candidate proteins were then verified by ELISA. Finally, we will select out the significant protein and a seven-target multiplex fecal protein biochip was generated and tested for 20 fecal samples to determine the effectiveness of the biochip on identifying CRC. And the value of the protein biochip would be discussed.

RESULTS: After tested by protein biochip of the fecal protein from 20 colorectal cancer patients and 20 healthy controls and levels of calprotectin, M2-pyruvatekinase, angiopoietin-2, fibroblast growth factor-23 (FGF-23), proteins of the matrix metalloproteinase, thrombopoietin (TPO) and interleukin-13 (IL-13) were significantly different between CRC and healthy controls. The sensitivity of all the seven proteins combined was 0.7, specificity was 0.4, and area under the receiver operating characteristics was 0.729. The most promising combinations of test proteins were FGF-23, TPO, and IL-13, reaching a sensitivity of 0.7 and a specificity of 0.7. The combination of FGF-23 and TPO scored highest with sensitivity of 0.7 and specificity of 0.8. Its mean that the combination of FGF-23 and TPO has the highest value for the diagnosis of CRC in our study.

CONCLUSION: A protein biochip composed of proteins found to be elevated in the feces of colorectal cancer patients has great potential as a noninvasive diagnostic for colorectal cancer. The addition of new protein biomarkers and technologies, as they are discovered, is an excellent avenue of future research.

Spacer-enhanced chymotrypsin-activated peptide-functionalized gold nanoparticle probes: a rapid assay for the diagnosis of pancreatitis

A spacer-enhanced FITC-labeled peptide self-assembled onto AuNPs was fabricated as a chymotrypsin activated fluorescent AuNP probe and was used for the diagnosis of pancreatitis with fecal specimens.

Global gas chromatography/time-of-flight mass spectrometry (GC/TOFMS)-based metabonomic profiling of lyophilized human feces

Gas chromatography mass spectrometry (GC/MS)-based fecal metabonomics represents a powerful systems biology approach for elucidating metabolic biomarkers of lower gastrointestinal tract (GIT) diseases. Unlike metabolic profiling of fecal water, the profiling of complete fecal material remains under-explored. Here, a gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) method was developed and validated for the global metabonomic profiling of human feces. Fecal and fecal water metabotypes were also profiled and compared. Additionally, the unclear influence of blood in stool on the fecal metabotype was investigated unprecedentedly. Eighty milligram of lyophilized feces was ultrasonicated with 1mL of methanol:water (8:2) for 30min, followed by centrifugation, drying of supernatant, oximation and trimethylsilylation for 45min. Lyophilized feces demonstrated a more comprehensive metabolic coverage than fecal water, based on the number of chromatographic peaks. Principal component analysis (PCA) indicated occult blood (1mgHb/g feces) exerted a negligible effect on the fecal metabotype. Conversely, a unique metabotype related to feces spiked with gross blood (100mgHb/g feces) was revealed (PCA, R(2)X=0.837, Q(2)=0.794), confirming the potential confounding effect of gross GIT bleeding on the fecal metabotype. This pertinent finding highlights the importance of prudent interpretation of fecal metabonomic data, particularly in GIT diseases where bleeding is prevalent.

Genetic and functional profiling of Crohn's disease: autophagy mechanism and susceptibility to infectious diseases

Crohn's disease is a complex disease in which genome, microbiome, and environment interact to produce the immunological background of the disease. Disease in childhood is more extensive and characterized by a rapid progression, leading to severe repercussions in the course of the disorder. Several genetic variations have been associated with an increased risk of developing the disease and most of these are also implicated in other autoimmune disorders. The gut has many tiers of defense against incursion by luminal microbes, including the epithelial barrier and the innate and adaptive immune responses. Moreover, recent evidence shows that bacterial and viral infections, as well as inflammasome genes and genes involved in the autophagy process, are implicated in Crohn's disease pathogenesis. The aim of this review is to establish how much the diagnostic system can improve, thus increasing the success of Crohn's disease diagnosis. The major expectation for the near future is to be able to anticipate the possible consequences of the disease already in childhood, thus preventing associated complications, and to choose the best treatment for each patient.

Low faecal haemoglobin concentration potentially rules out significant colorectal disease

AIM

The study aimed to determine whether faecal haemoglobin (Hb) concentration can assist in deciding who with lower abdominal symptoms will benefit from endoscopy.

METHOD

Faecal Hb concentrations were measured on single samples from 280 patients referred for lower gastrointestinal tract endoscopy from primary care in NHS Tayside who completed a faecal immunochemical test (FIT) for Hb and underwent subsequent endoscopy.

RESULTS

Among 739 invited patients, FIT and endoscopy were completed by 280 (median age 63 (18-84) years; 59.6% women), with a median time between FIT and endoscopy of 9 days. Six (2.1%) participants had cancer, 23 (8.2%) had high-risk adenoma (HRA) (more than three adenomas or any > 1 cm), 31 (11.1%) low-risk adenoma (LRA) and 26 (9.3%) inflammatory bowel disease (IBD) as the most serious diagnosis. Those with cancer had a median faecal Hb of > 1000 ng Hb/ml buffer. Those with cancer + HRA + IBD had a median faecal Hb concentration of 75 ng Hb/ml buffer (95% CI 18-204), which was significantly higher than that of all remaining participants without significant colorectal disease (P < 0.0001). Using a cut-off faecal Hb concentration of 50 ng Hb/ml buffer, negative predictive values of 100.0%, 94.4%, 93.4% and 93.9% were found for cancer, HRA, LRA and IBD. Patients with reasons for referral other than rectal bleeding and family history did not have high faecal Hb concentrations.

CONCLUSION

Faecal Hb concentration measurements have considerable potential to contribute to reducing unnecessary endoscopy for the majority of symptomatic patients.

A future for faecal haemoglobin measurements in the medical laboratory

Guaiac-based faecal occult blood tests (gFOBT) are still used in asymptomatic population bowel screening programmes but are being replaced by faecal immunochemical tests (FIT) for haemoglobin. gFOBT have many well-documented disadvantages and there is little evidence for their use in assessment of the symptomatic. Many laboratories have eliminated gFOBT from their approved repertoires by invoking the authoritative published guidelines. Data continue to accumulate that gFOBT are obsolete. FIT are available in two formats, qualitative and quantitative, the latter having advantages that the faecal haemoglobin concentrations are measured and cut-off concentrations that stimulate further investigation can be user-defined. There is growing evidence that FIT would be useful in a spectrum of clinical settings in addition to screening. All laboratories should have FIT in their existing repertoire. For some uses, qualitative FIT would be adequate. However, much evidence has accumulated that measurements of faecal haemoglobin concentrations are beneficial for the assessment of both disease severity and the future risk of colorectal neoplasia. Interpretation requires appreciation that faecal haemoglobin concentrations are higher in men than women and rise with age. It might well be that risk scoring systems that take gender and age into account, possibly with other factors including symptoms, will benefit individuals. Laboratories should consider how quantitative faecal haemoglobin measurements could be brought into routine practice and included in their forward planning. External quality assessment is needed. Specialists in laboratory medicine are urged to play a significant role in the research and development still required to make this a truly mature investigation.

Faecal markers of gastrointestinal inflammation

Gastrointestinal (GI) symptoms including abdominal pain, bloating and diarrhoea are a relatively common reason for consulting a physician. They may be due to inflammatory bowel disease (inflammatory bowel disease; Crohn's disease, ulcerative colitis and indeterminate colitis), malignancy (colorectal cancer), infectious colitis or irritable bowel syndrome (IBS). Differentiation between these involves the use of clinical, radiological, endoscopic and serological techniques, which are invasive or involve exposure to radiation. Serological markers include C-reactive protein, erythrocyte sedimentation rate and antibodies (perinuclear antineutrophil cytoplasm antibody and anti-Saccharomyces cerevisiae antibody). Faecal markers that can aid in distinguishing inflammatory disorders from non-inflammatory conditions are non-invasive and generally acceptable to the patient. As IBS accounts for up to 50% of cases presenting to the GI clinic and is a diagnosis of exclusion (Rome III criteria), any test that can reliably distinguish IBS from organic disease could speed diagnosis and reduce endoscopy waiting times. Faecal calprotectin, lactoferrin, M2-PK and S100A12 will be reviewed.

A proposal to standardize reporting units for fecal immunochemical tests for hemoglobin

Fecal immunochemical tests for hemoglobin are replacing traditional guaiac fecal occult blood tests in population screening programs for many reasons. However, the many available fecal immunochemical test devices use a range of sampling methods, differ with regard to hemoglobin stability, and report hemoglobin concentrations in different ways. The methods for sampling, the mass of feces collected, and the volume and characteristics of the buffer used in the sampling device also vary among fecal immunochemical tests, making comparisons of test performance characteristics difficult. Fecal immunochemical test results may be expressed as the hemoglobin concentration in the sampling device buffer and, sometimes, albeit rarely, as the hemoglobin concentration per mass of feces. The current lack of consistency in units for reporting hemoglobin concentration is particularly problematic because apparently similar hemoglobin concentrations obtained with different devices can lead to very different clinical interpretations. Consistent adoption of an internationally accepted method for reporting results would facilitate comparisons of outcomes from these tests. We propose a simple strategy for reporting fecal hemoglobin concentration that will facilitate the comparison of results between fecal immunochemical test devices and across clinical studies. Such reporting is readily achieved by defining the mass of feces sampled and the volume of sample buffer (with confidence intervals) and expressing results as micrograms of hemoglobin per gram of feces. We propose that manufacturers of fecal immunochemical tests provide this information and that the authors of research articles, guidelines, and policy articles, as well as pathology services and regulatory bodies, adopt this metric when reporting fecal immunochemical test results.