Should stored serum of patients previously tested for celiac disease serology be retested for transglutaminase antibodies?

INTRODUCTION

Tissue transglutaminase (tTG) antibodies are currently recognized as a highly sensitive indicator of celiac disease (CD). Although a high concordance rate between tTG antibodies and anti-endomysial antibodies (EMA) has been reported up to a third of known CD patients are positive for only one of these antibodies.

AIM

To determine whether in laboratories in which serum samples previously examined for CD serology markers had not been discarded, these samples should be tested for tTG antibodies.

METHODS

Fifty-eight stored (frozen at -70) serum samples of patients previously found to be EMA-negative but positive for one or more of the non-EMA markers: antigliadin antibodies (AGA)-IgA, AGA-IgG, antireticulin antibodies, were tested for anti-tTG antibodies (IMMCO Diagnostics). In patients found to be tTG positive, medical charts were reviewed and patients or their physicians contacted.

RESULTS

Twelve of fifty-eight (20.7%) samples were found to be anti-tTG positive. These included: group A: 3/3 samples previously positive for AGA-IgA, AGA-IgG, and antireticulin antibodies. Group B: 3/16 samples positive for AGA-IgA and AGA-IgG. Group C: 3/4 samples positive for AGA-IgA and group D: 3/35 samples positive for AGA-IgG. Of the 12 positive patients, 1 was a 2-year-old boy, 5 were lost to follow up, and 7 underwent an intestinal biopsy. In 3 of these 7 patients, the biopsy was compatible with CD; 2 of these 3 patients were from group A and 1 from group B.

CONCLUSIONS

In laboratories where stored serum samples are available, EMA-negative samples previously found to be positive for at least 2 other CD markers should be retested for tTG antibodies.