乳糜泻诊断的研究进展

乳糜泻(CD)是具有遗传易感性的个体因摄入麸质而触发的一种免疫介导的全身性疾病。其特点为小肠(尤其是空肠)黏膜绒毛的萎缩以及营养物质吸收不良,禁食含麸质的食物(小麦、黑麦、大麦)能使症状缓解,再进食可迅速复发。以往认为本病少见,目前世界范围的流行病学资料证实其发病率并不低且逐渐增加。本文就CD诊断的研究进展作一综述。     

Celiac Disease Diagnosis: Simple Rules Are Better Than Complicated Algorithms

Celiac disease is the only treatable autoimmune disease, provided that a correct diagnosis is achieved and a strict, lifelong gluten-free diet is implemented. The current diagnostic algorithm for celiac disease includes initial screening serological tests, followed by a confirmatory small intestinal biopsy showing the autoimmune insult typical of celiac disease. The biopsy, considered the diagnostic gold standard, has been recently questioned as a reliable and conclusive test for every case. Indeed, the wide variability of celiac disease-related findings suggests that it is difficult to conceptualize the diagnostic process into rigid algorithms that do not always cover the clinical complexity of this disease. Instead we find clinically useful the shifting to a quantitative approach that can be defined as the “4 out of 5” rule: the diagnosis of celiac disease is confirmed if at least 4 of the following 5 criteria are satisfied: typical symptoms of celiac disease; positivity of serum celiac disease immunoglobulin, A class autoantibodies at high titer; human leukocyte antigen (HLA)-DQ2 or DQ8 genotypes; celiac enteropathy at the small bowel biopsy; and response to the gluten-free diet.     

Anti-transglutaminase IgA ELISA: Clinical Potential and Drawbacks in Celiac Disease Diagnosis

Background: Since the identification of tissue transglutaminase (tTG) as the antigen for the antiendomysial antibodies (EMA), several antigen-specific immunoassays have been reported for celiac disease (CD) screening. A first objective was to evaluate the suitability for CD screening of three different IgA tTG ELISAs, two of them based on guinea pig liver tTG (gp-tTG) (an in-house ELISA with a partially purified extract and a commercial ELISA with purified gp-tTG antigen) and a third recombinant human tTG (rh-tTG) ELISA. The results are compared with EMA and with the final clinical diagnosis. A second objective was to analyze antibody reactivities in those patients with anti-tTG and EMA discrepancies. Methods: ELISA and EMA tests were used to measure IgA anti-tTG levels in sera from 259 patients (107 had CD and 72 had Type I diabetes mellitus). Results: The purified gp-tTG ELISA was highly sensitive (97.7%) and specific (98.8%) in the detection of CD, almost equaling EMA. Rh-tTG ELISA did not improved the sensitivity of EMA, but its specificity was slightly superior. Immunoblot analysis with partially purified gp-tTG extract, the antigen most frequently used for anti-tTG detection, showed that the majority of false positives were due to IgA reactivities to contaminant proteins present in the liver antigenic extract. This low specificity was particularly problematic in diabetics. Conclusion: Purified tTG ELISAs, either with purified guinea pig liver or recombinant human antigens, can be used as quantitative and observer-independent alternatives to the traditional and time-consuming EMA in the screening of CD.     

Suboptimal Performance of IgG Anti-tissue Transglutaminase in the Diagnosis of Celiac Disease in a Tropical Country

Serological tests using human IgA-anti-tTG have been reported to have high sensitivity and specificity in diagnosis of celiac disease. There is a paucity of data on the use of human IgG-anti-tTG in diagnosis of celiac disease. Ninety-two patients with clinical suspicion of celiac disease who underwent duodenal mucosal biopsy and celiac serology using human IgG-anti-tTG were included in this retrospective study. Diagnostic accuracy of human recombinant IgG-anti-tTG serological test for celiac disease was evaluated. Indications for celiac serological testing were diarrhea (92.3%), hypoalbuminemia (39.1%), and anemia (35.9%). Eighteen patients were diagnosed with having celiac disease and 14 (77.8%) of them were IgG-anti-tTG positive. Of the remaining 74 patients, eight (10.8%) were false-positive for IgG-anti-tTG. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of IgG-anti-tTG in celiac disease were 77.8, 89.1, 63.6, 94.2, and 87%, respectively. Human IgG-anti-tTG alone does not perform well as a diagnostic tool for celiac disease. The utility of anti-endomysial antibodies in a similar clinical setting needs to be evaluated.     

Delay in Diagnosis of Celiac Disease in Patients Without Gastrointestinal Complaints

Purpose

The purpose of our study is to investigate the delay in diagnosis of patients with biopsy-proven celiac disease in those who present with gastrointestinal complaints vs nongastrointestinal complaints at our tertiary care center. Celiac disease is an autoimmune disorder that affects approximately 1% of the population worldwide. Celiac disease can have variable clinical presentations; it can be characterized by predominately gastrointestinal symptoms, or it may present without any gastrointestinal symptoms.