From the Guidelines
Positive dim glad IgG antibodies are indicative of celiac disease, but not definitively diagnostic on their own, and should be interpreted alongside other serological tests and intestinal biopsy results. According to the guidelines from the British Society of Gastroenterology 1, the diagnosis of coeliac disease involves a combination of serological tests, including IgA-TG2, IgG-TG2, IgG-DGP, EMA, and HLA, as well as intestinal biopsy showing villous atrophy. The study by Ludvigsson et al. 1 provides an algorithm for the diagnosis of coeliac disease, which highlights the importance of considering multiple factors, including serological test results and biopsy findings.
In patients with positive IgG antibodies, such as dim glad IgG, it is essential to consider other serological tests, particularly tissue transglutaminase (tTG) IgA antibodies and endomysial antibodies, which are considered more reliable markers 1. The guidelines for the investigation of chronic diarrhoea in adults 1 also emphasize the importance of serological testing for coeliac disease in patients presenting with chronic diarrhoea, with a combined sensitivity and specificity of over 90% when using EMA and TTG IgA in combination.
However, it is crucial to note that patients should maintain a gluten-containing diet before testing to avoid false-negative results 1. If dim glad IgG antibodies are positive, further evaluation by a gastroenterologist is recommended for additional testing and possible endoscopy with biopsy to confirm the diagnosis before starting a gluten-free diet.
Key points to consider in the diagnosis of coeliac disease include:
- Combination of serological tests, including IgA-TG2, IgG-TG2, IgG-DGP, EMA, and HLA
- Intestinal biopsy showing villous atrophy
- Maintenance of a gluten-containing diet before testing
- Further evaluation by a gastroenterologist for additional testing and possible endoscopy with biopsy to confirm the diagnosis.
From the Research
Celiac Disease Diagnosis
- The presence of dim glad IgG antibodies is not solely indicative of celiac disease, as it can also be found in individuals with other conditions 2.
- However, the combination of IgG anti-deamidated gliadin peptides (DGP) and IgA anti-tissue transglutaminase (TG2) antibodies has shown high diagnostic performance for untreated celiac disease 3, 4.
- IgG anti-TG2 antibodies can be used to detect celiac disease in patients with selective IgA deficiency, with a sensitivity of 96% and a specificity of 99.5% 3.
- The combination of IgG anti-DGP and IgA anti-TG2 antibodies has been shown to have a sensitivity of 98-99% and a specificity of 100% for diagnosing celiac disease 4.
- It is essential to consider the results of multiple antibody tests, including IgA and IgG antibodies, to accurately diagnose celiac disease 3, 2, 4.