A New opportunity for diagnosis of diseases of Gastro-Intestinal tract.
Calprotectin belongs to the group of Ca-binding proteins of the S100 family. It is present in large amounts in neutrophilic granulocytes, where it accounts for 5% of total proteins and 60% of the proteins of cytoplasmatic portion; in smaller amounts, this protein has been found in monocytes and activated macrophages.
Calprotectin is stable in stool samples for several days at room temperature and much longer periods at -20°C. The faecal concentration of Calprotectin correlates with the histologic and endoscopic patterns of the intestinal inflammation in IBD patients (Crohn's disease and Ulcerative Colitis)
Calprest and CalFast are not invasive screening tests that can reliably detect the presence of an inflammation of the intestinal mucosa and can be used in the following conditions:
- Differential diagnosis (IBD/IBS)
- Control of the correct course of IBD and monitoring of the therapeutic strategy
- Prediction of clinical relapses
- HELICOBACTER PYLORI:
Helicobacter pylori is a Gram-negative, microaerophilic bacterium found in the stomach. It is also linked to the development of duodenal ulcers and stomach cancer. H. pylori's helix shape (from which the generic name is derived) is thought to have evolved to penetrate the mucoid lining of the stomach. However, over 80 percent of individuals infected with the bacterium are asymptomatic and it has been postulated that it may play an important role in the natural stomach ecology.
More than 50% of the world's population harbor H. pylori in their upper gastrointestinal tract. Infection is more prevalent in developing countries, and incidence is decreasing in Western countries.
Gastric infection by Helicobacter pylori is the most important cause of gastroduodenal diseases and represents a risk factor for the development of gastric malignancies.
The search of H. pylori in the gastric mucosa has two aims:
1) to diagnose the infection
2) to check eradication after the therapy.
H.pylori search can be done by means of invasive methods (histology, culture, rapid urease test) and by non-invasive methods (breath test,determination of anti-H. pylori antibodies in serum, search of bacterial antigens in stools). Breath test allows both the diagnose and the control of eradication, but it is expansive and the patient is asked to ingest a meal containing labelled urea. The major drawback of the serologic determination of anti-H. pylori antibodies is represented by the difficulty of controlling the eradication, because of the slow clearance of antibody titer.
The search of H. pylori antigenic material in stools is characterized by several advantages:
- The presence of H. pylori antigens is representative of the active infection, and therefore is particularly suitable both for diagnose and for the control of eradaction:
- The patient is not directly involved in the test; and
- The test is cheaper than breath test.
According to the Maastricht “Consensus Report" (2000), all adults younger than 45 presenting with persistent dyspepsia (with the exclusion of GERD - Gastro-Esophageal disease Reflux Disease- patients and NSAID -non-steroidal anti-inflammatory drugs- users) should be screened and, if found positive, treated. The fecal antigen test is believed the most effective assay for the diagnosis of Helicobacter pylori infection
*Both Helicobacter pylori infection and non-steroidal anti-inflammatory drug (NSAIDS) contribute both to increasing gastrict/duodenal ulcers and bleeding risk (Am J Manag Care 2001 sep; 7 (12suppl):S402-3).
*The stool antigen test is considered to be one of the preferred test for the in vitro diagnosis of Helicobacter pylori infection. (The Maastricht Consensus Report 2-2000)
Anti-Saccharomyces cerevisiae antibodies (ASCA), along with perinuclear antineutrophil cytoplasmic antibodies (pANCA), are among the two most useful and often discriminating markers for colitis and Crohn disease. ASCA are mostly used with Crohn's patients, whereas pANCA are more indicated for ulcerative colitis (UC) patients.
The antibodies to the mannan structure of Saccharomyces cerevisiae had been known for several years and their association with Crohn's Disease has been proved. Their use in diagnostics has not been appreciated until the discovery of the ANCAs, which are present in ulcerative colitis (UC).
Thus, it has become possible the combined use of these two tests to differentiate Crohn's disease from the UC. The clinical appearance of these patients is often similar and the diagnosis depends from clinical data, such as X-ray, endoscopic and the laboratory. A serological test may be helpful to avoid a biopsy, especially in pediatric patients.
Sensitivity and specificity have not clearly defined yet. Certain studies prove that 40-80% of patients with UC have ANCA and 0-20% of patients with Crohn's disease have ANCA, whereas 0-10% of patients with UC havethe ASCA and 50-70% of Crohn's disease patients have the ASCA.
In one study. the combination of ANCA positive with ASCA negative for the diagnosis of UC reported a sensitivity of 57% and a specificity of 97%. while the combination of negative ANCA positive with ASCA for the diagnosis of Crohn's disease gave a sensitivity of 49% and a specificity of 97%.
Enzyme immunoassay kit for the diagnosis of intolerance to cow's milk proteins by means of the detection of specific IgG antibodies against ß-lactoglobulin.