Coeliac Disease (CD) Case Finding and Diet Monitoring by Point-of-Care
Testing
Posted 10/19/2005

I.R. Korponay-Szabó; T. Raivio; K. Laurila; J. Opre; R. Király; J.B.
Kovács; K. Kaukinen; L. Fésüs; M. Mäki

Summary and Introduction
Summary
Background: Immunoglobulin A class transglutaminase autoantibodies are
highly predictive markers of active coeliac disease, a disorder
difficult to recognize solely on clinical grounds.
Aims: To develop and evaluate a simple rapid test for point-of-care
detection of coeliac autoantibodies.
Methods: The novel whole blood test utilizes the patient's endogenous
transglutaminase in red blood cells for detection of
transglutaminase-specific immunoglobulin A antibodies present in the
blood sample, with normal plasma immunoglobulin A detection as positive
test control. We evaluated 284 patients under suspicion of coeliac
disease and undergoing jejunal biopsy, and 263 coeliac patients on a
gluten-free diet, 383 being tested prospectively in a point-of-care
setting. Results were compared with histology, conventional serum
autoantibody results and dietary adherence.
Results: The rapid test showed 97% sensitivity and 97% specificity for
untreated coeliac disease, and identified all immunoglobulin
A-deficient samples. Point-of-care testing found new coeliac cases as
efficiently as antibody tests in laboratory. Coeliac autoantibodies
were detected onsite in 21% of treated patients, while endomysial and
transglutaminase antibodies were positive in 20% and 19%, respectively.
The positivity rate correlated with dietary lapses and decreased on
intensified dietary advice given upon positive point-of-care test
results.
Conclusions: Point-of-care testing was accurate in finding new coeliac
cases and helped to identify and decrease dietary non-compliance.

Introduction
Coeliac disease is an autoimmune gastrointestinal disorder induced by
ingestion of gluten found in wheat, rye and barley.[1,2] The active
disease is characterized by gluten-dependent autoantibodies against
endomysium (EMA), a complex connective tissue structure surrounding
smooth muscle cells, and more precisely, against the protein type 2
('tissue') transglutaminase (TG2), the coeliac autoantigen anchored to
endomysial collagen by fibronectin.[3,4] Detection of these
autoantibodies in the serum is a useful means of identifying new
coeliac patients presenting with only mild gastrointestinal symptoms,
non-specific general complaints or extraintestinal manifestations, or
in populations in general.[1,5-8] A further important application of
serological tests is the regular monitoring of dietary adherence in
treated patients, as the autoantibodies disappear from the serum on a
strict gluten-free diet.[9] There is thus call for quick,
easy-to-perform, economical and widely accessible coeliac antibody
tests which can be carried out at the first care-taking level locally.

Currently, coeliac-specific serum antibody tests are centralized in
specialized laboratories to ensure appropriate sensitivity and
specificity.[9] Testing is costly and the turnaround time of results
may be relatively long.

Natural human TG2 protein is also found within the red blood cells,[10]
and thus in any diagnostic blood specimens comprising whole blood. This
easily available endogenous TG2 antigen has, after liberation by
haemolysis, the potential to bind to and thereby detect coeliac
autoantibodies present in the same sample without need for purified,
external TG2 antigen,[11] serum separation, and possibly even without a
laboratory reader. This innovative means of detection thus offers an
opportunity for point-of-care testing (POCT), defined as performing a
diagnostic procedure in a variety of environments outside the central
laboratory.[12]

In the present study, we showed a simple self-TG2-based rapid whole
blood test to be accurate in detecting untreated coeliac disease. The
performance of the test was further evaluated in point-of-care (POC)
settings in finding new cases and monitoring treatment.