Tissue transglutaminase antibody levels predict IgA deficiency

Area of Science:

• Clinical immunology
• Gastroenterology
• Diagnostic testing

Background:

• Serum tissue transglutaminase immunoglobulin A (tTG IgA) is the primary screening test for coeliac disease.
• IgA deficiency in coeliac patients can lead to false-negative tTG IgA results.
• Total IgA levels are often measured alongside tTG IgA to mitigate this risk.

Purpose of the Study:

• To evaluate if serum tTG IgA levels can predict IgA deficiency.
• To determine if total IgA testing can be avoided in certain individuals.
• To optimize coeliac disease screening protocols.

Main Methods:

• Retrospective analysis of 9,429 serum tTG IgA and total IgA levels.
• Data collected from children and young adults in East England (2007-2011).
• Receiver operating characteristic (ROC) curve analysis to identify predictive cut-off values.

Main Results:

• Overall IgA deficiency prevalence was low (0.9%).
• A tTG IgA cut-off of ≥0.10 μ/mL predicted the absence of IgA deficiency (sensitivity 0.92, specificity 0.84).
• Only 16.4% of patients required total IgA measurement to rule out false negatives.

Conclusions:

• Quantitative tTG IgA measurement can avoid unnecessary total IgA testing.
• tTG IgA values <0.10 μ/mL warrant further total IgA measurement.
• This approach streamlines coeliac disease assessment and reduces testing burden.