New faecal tests in gastroenterology

Abstract

Most abdominal disorders present with a limited number of overlapping symptoms. Blood tests are not routinely available for use in diagnosis and so investigation tends to require complex imaging procedures or endoscopy and biopsy. These are invasive for the patient, may be associated with morbidity and mortality and have considerable resource implications. Biochemical tests on a single sample of faeces are therefore a valuable alternative. Measurement of faecal calprotectin has been shown to have a role in the diagnosis of inflammatory bowel disease and in its monitoring. Lactoferrin is also of benefit used in this way. Faecal elastase has been demonstrated to be of use in the diagnosis of pancreatic insufficiency. A number of faecal markers have been explored in colorectal cancer. Faecal occult blood testing is used for population screening, but the metabolomic marker tumour, M2-pyruvate kinase, has potential for use in both diagnosis and screening. DNA testing has advantages in colorectal cancer but the exact applications of such tests require further evaluation.

Inflammatory bowel diseases: from pathogenesis to laboratory testing

“…A complete blood (Table 1). Therefore fecal calprotectin, with a sensitivity of 64%-95% and a specificity of 79%-93%, has been suggested as an index of organic bowel disease [43]. Nonetheless, an increased fecal level of calprotectin and/or lactoferrin leads to the identification of patients most likely to have IBDs and calls for immediate endoscopy; moreover, the use of fecal calprotectin/lactoferrin for screening allows a reduction in the number of negative findings at endoscopy in both adults and young patients with suspected IBDs [45].…”

“…cleavage is involved in the antimicrobial activity of lactoferrin. Both proteins are resistant to bacterial proteolysis, their integrity being maintained in stools, where they can easily be identified; since they remain stable in feces for up to 1 week when stored at room temperature, and for months when stored at −20°C [43], it may be possible to adopt low stringency transport conditions for fecal material, although transport in refrigerated boxes is advisable for a better overall standardization of the pre-analytical phase. Laboratory processing of the samples includes: 1) sampling and dilution; and 2) analysis.…”

Newer Fecal Tests: Opportunities for Professionals in Laboratory Medicine

“…We advocate that, whenever possible, PLMs should participate with clinical colleagues in studies of diagnostic accuracy and encourage adherence to these guidelines. The work of Kok and colleagues builds on previous studies of fecal calprotectin, which have amply demonstrated this marker to be useful in differential diagnosis and to be potentially useful in clinical management (8 ). Moreover, the available data support the view that the lack of a detectable calprotectin concentration in a low-risk patient supports the discharge of the patient without further invasive investigation.…”

“…In consequence, Kok and colleagues (4 ) rightly considered that the tests were not very useful for ruling in, largely because calprotectin is a general protein marker of gut damage and has even been suggested to be of value in colorectal cancer screening (8 ). Conversely, the negative predictive values, a major determinant of clinical utility in this primary-care setting, were Ͼ90%.…”

“…Moreover, POCTs have a number of telling disadvantages, including that the cutpoint concentrations between negative and positive results are set by the manufacturers of the devices and cannot be adjusted. It is vital to recognize that the cutpoint concentrations for available calprotectin tests (8 ) and FITs (5 ) differ substantially. Different cutpoint concentrations will lead to different clinical performance characteristics, and thus the work of Kok and colleagues (4 ) may not be transferable over time and geography if other tests are used.…”