Value of faecal alpha-1-antitrypsin, haemoglobin and a chemical occult blood test in the detection of gastrointestinal disease

Emerging Biomarkers for the Diagnosis and Monitoring of Inflammatory Bowel Diseases

There is currently no single test available to confidently diagnose cases of inflammatory bowel disease (IBD). Physicians rely on a number of diagnostic tools, including clinical evaluation, serum testing, and imaging, which are used on conjunction with endoscopic evaluation. It is often difficult to determine whether patients with abdominal pain and change in bowel habit have functional bowel symptoms or whether they have a true diagnosis of IBD. Even once a diagnosis of IBD has been made, a significant proportion of patients are labeled with the term "indeterminate colitis" where histological sampling cannot confidently subclassify patients as either Crohn's or ulcerative colitis. Colonoscopy is an inconvenient and uncomfortable test for most patients. In addition, it is not without serious risks of perforation, as well as risks which can be associated with sedation and analgesia given during the procedure. The use of biomarkers to aid in the diagnosis, subclassification, and monitoring of IBD is an ever expanding area. In this review, we have concentrated on noninvasive biomarkers of IBD, because these are more acceptable to patients and easier to perform in everyday clinical practice. We will first touch on those biomarkers currently well established and in wide clinical use, such as C-reactive protein, erythrocyte sedimentation rate. Faecal calprotectin and their use in the diagnosis of IBD. Following on, we will review more novel biomarkers and their use in subclassification and monitoring of IBD, including a variety of antibodies, genetics, and microRNAs, as well as touching on metabolomics.

Are faecal markers good indicators of mucosal healing in inflammatory bowel disease?

AIM: To review the published literature concerning the accuracy of faecal inflammatory markers for identifying mucosal healing.

METHODS: Bibliographical searches were performed in MEDLINE electronic database up to February 2015, using the following terms: “inflammatory bowel disease”, “Crohn´s disease”, “ulcerative colitis”, “faecal markers”, “calprotectin”, “lactoferrin”, “S100A12”, “endoscop*”, “mucosal healing”, “remission”. In addition, relevant references from these studies were also included. Data were extracted from the published papers including odds ratios with 95%CI, P values and correlation coefficients. Data were grouped together according to each faecal marker, Crohn’s disease or ulcerative colitis, and paediatric compared with adult study populations. Studies included in this review assessed mucosal inflammation by endoscopic and/or histological means and compared these findings to faecal marker concentrations in inflammatory bowel diseases (IBD) patient cohorts. Articles had to be published between 1990 and February 2015 and written in English. Papers excluded from the review were those where the faecal biomarker concentration was compared between patients with IBD and controls or other disease groups, those where serum biomarkers were used, those with a heterogeneous study population and those only assessing post-operative disease.

RESULTS: The available studies show that faecal markers, such as calprotectin and lactoferrin, are promising non-invasive indicators of mucosal healing. However, due to wide variability in study design, especially with regard to the definition of mucosal healing and evaluation of marker cut offs, the available data do not yet indicate the optimal roles of these markers. Thirty-six studies published between 1990 and 2014 were included. Studies comprised variable numbers of study participants, considered CD (15-164 participants) or UC (12-152 participants) separately or as a combined group (11-252 participants). Eight reports included paediatric patients. Several indices were used to document mucosal inflammation, encompassing eleven endoscopic and eight histologic grading systems. The majority of the available reports focused on faecal calprotectin (33 studies), whilst others assessed faecal lactoferrin (13 studies) and one study assessed S100A12. Across all of the biomarkers, there is a wide range of correlation describing the association between faecal markers and endoscopic disease activity (r values ranging from 0.32 to 0.87, P values ranging from < 0.0001 to 0.7815). Correlation coefficients are described in almost all studies and are used more commonly than outcome measures such as sensitivity, specificity, PPV and/or NPV. Overall, the studies that have evaluated faecal calprotectin and/or faecal lactoferrin and their relationship with endoscopic disease activity show inconsistent results.

CONCLUSION: Future studies should report the results of faecal inflammatory markers in the context of mucosal healing with clear validated cut offs.

Paediatric GI emergencies

Paediatric GI emergencies constitute a wide range of gut pathologies ranging from those that are common, easily diagnosed and treated to conditions that are rarer, often more severe and challenging to manage. Among a myriad of ordinary clinical symptoms and signs physicians have to identify the child with a serious, life-threatening pathology and initiate the appropriate diagnostic and therapeutic pathway. The aim of the review is to present and discuss a selection of key paediatric GI emergencies that provide challenges in diagnosis and treatment. These conditions are classified by their presentation or pathogenesis and include inflammatory conditions, those presenting with GI obstruction or haemorrhage and the ingestion of foreign bodies or caustic substances. The most recent advances regarding the management of these entities are discussed along with key areas of clinical practice and future research.

The effect of toilet sanitizers and detergents on immunological occult blood tests

Effects of time-releasing toilet bowl sanitizers and their main constituents, detergents, on immunological fecal occult blood tests were examined. Six kinds of toilet sanitizers and 19 kinds of detergents were included. Patients' fecal samples and hemoglobin solutions were measured by means of quantitative immunological fecal occult blood tests after being mixed with sanitizer or detergent solutions. Marked reduction in hemoglobin concentration or antigenicity was observed after the addition of sanitizers or detergents at a final concentration of 0.5 g/l. Most of these inhibitory reactions were dose dependent. In contrast with the immunological method, the chemical method using o-tolidine and guaiac were not affected by the detergents tested. In sampling feces for immunological fecal occult blood tests, contact of samples with sanitizer solutions should be avoided.

Diagnostic value of a guaiac occult blood test and faecal alpha 1-antitrypsin

This study evaluates the diagnostic accuracy of a faecal occult blood test and faecal alpha 1-antitrypsin in the investigation of patients with gastrointestinal symptoms or iron deficiency anaemia. One hundred and seventy nine patients with either iron deficiency anaemia (n = 67), changed bowel habit and aged > 39 years (n = 107), or a history suggestive of melaena (n = 5) provided faecal samples. After investigation, 32 patients had a diagnosis of possible gastrointestinal bleeding and 139 patients had no evidence of gastrointestinal bleeding. Eight patients had a cause of enteric protein loss in the absence of gastrointestinal bleeding and were excluded from subsequent analysis. The faecal alpha 1-antitrypsin test was diagnostically more accurate than the guaiac test in identifying probable gastrointestinal bleeding (82% and 72% respectively, p < 0.05). This faecal alpha 1-antitrypsin test was also more specific (83% and 72% respectively, p < 0.05), but was not significantly more sensitive (78% and 72% respectively). The sensitivity of these tests was insufficient to recommend their use for most patients in this study.

Enteric alpha-1-antitrypsin loss and comparison with Okokit II and Haemoccult for the detection of colorectal cancer

Faecal samples from patients with symptomatic colorectal cancer (n = 19) and from control subjects (n = 54) were analysed for alpha-1-antitrypsin (A1AT) and compared with Haemoccult and Okokit II. A1AT was also measured in paired samples of normal colonic mucosa and cancer tissue (n = 16) and in media from four human colorectal cell lines (COLO 320 DM, SW620, HT29, LS 174T). Faecal A1AT concentrations were greater than controls (P < 0.0001) and detected 12 (63%) patients with cancer compared to 10 (53%) by Okokit II and 7 (37%) by Haemoccult (P > 0.05). A1AT concentrations from colonic mucosa (median, range: 0.46, 0.17-0.79 mg/g wet wt) were greater (P = 0.01) than cancer tissue (0.29, 0.13-0.74 mg/g wt wt). Adjusting for albumin, A1AT concentrations from mucosa (12.0, 3.8-32.2 mg/g albumin) remained greater (P = 0.003) than for cancer tissue (5.9, 2.4-21.4 mg/g albumin). A1AT was not detected in any of the cell-line media. The most likely mechanisms for increased faecal A1AT concentrations, apart from increased blood loss, are increased cell turnover or leakage from epithelial tight junctions. The use of faecal A1AT measurement for the detection of colorectal cancer deserves further assessment.