Background Coeliac disease (CD) is common. Response to a gluten-free diet is assessed through serial measurement of tissue transglutaminase (TTG) antibody titre. However, the relationship of TTG titres to symptoms and the speed of normalisation is poorly understood.

Methods Patients seen in 2020, and under follow-up in the Southampton CD clinic, had blood results, growth measures and symptom data collated. Time to normalisation, predictors of normalisation and relationship of TTG to growth/symptoms were assessed.

Results 57 patients were included. All had TTG results from the time of diagnosis and follow-up. All families reported dietary compliance.

Median TTG at diagnosis was 100 μ/L (range 0.3–4360), 94.7% of the patients had symptoms compatible with CD. At 6–12 months after diagnosis, the median TTG was 3.8 μ/mL (range 0.3–133). In terms of response, 29 of the 57 patients (50.9%) had a TTG below 4 μ/mL (upper normal limit). A further 25 patients (43.9%) had a TTG<10 times the upper limit of normal. Ten patients (17.5%) had a persistently high TTG (median=8.55 μ/mL, range 4.1–303) after >12 months.

TTG at diagnosis was correlated with TTG at 6–12 months, β=0.542, p=0.000016. Patients with TTG<10 times the upper limit of normal at diagnosis group were more likely to have normalised at 6–12 months compared with >10 times normal (85% vs 32.4%, p=0.0015). TTG titres did not correlate with growth measures (Z-scores) at diagnosis or at follow-up.

Conclusions Normalisation of TTG levels occurs within 6–12 months for around half of patients. Higher TTG levels at diagnosis take longer to normalise. The role of compliance is unclear.