Serological markers in subclinical and clinical gluten enteropathy

• An enzyme-linked immunosorbent assay (ELISA) has been developed for the measurement of anti-gliadin antibodies (AGA), thereby providing a practical and cheap assay for use in the diagnosis of coeliac disease (CD). Since gliadin is a common food antigen for most people, a large group of apparently healthy blood donors (n=l866) was analysed, as well as children and adults with symptoms more or less suggesting CD. The effects of various cut-offvalues on the sensitivity, specificity and predictive value (PV) of the test were calculated, both alone and together with anti-endomysium antibodies (EMA). A high prevalence value, of at least 1/256 (7!1866), for gluten enteropathy (GE) was found in the blood donor population. Moreover, a high frequency of CD among fanners with diffuse symptoms, conceivably due to a high exposure to gluten by inhalation, was also observed. It was impossible to combine high sensitivity with high specificity for both IgA- and IgG AGA, and vice versa, in adults. A significant increase in the mean lgA AGA level with age was seen when the blood donors were divided into age groups. A positive PV of 18-25% was found for IgA-AGA, depending on how-the cut-off value was defined. For IgG-AGA the positive PV was 0% (0/35) among asymptomatic subjects. IgA-EMA yielded both high specificity and a high positive PV, but a lower sensitivity than IgA-AGA, especially in children younger than 2 years, with signs of CD. When screening for GE in a population with expected low prevalence, measurement of IgA-AGA is suggested as a primary test because of fairly good sensitivity, technical simplicity, and low cost. Sera found to be positive are then re tested with IgA-EMA, which gives a positive PV close to 100%. For populations with a moderate or high expected prevalence for CD, our results indicate that different tests should be used depending on the age of the population studied. In younger children ( < 2 years old) lgA-AGA yielded a high sensitivity (lOO%) and a high specificity (86%). fu older children (> 2 years old) and adults the use of IgA-EMA seems more suitable, because of the high specificity (99-100%) and positive PV (95-100% ). Since, however, the negative PV was not 100%, a negative test result does not exclude CD.

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