ESPE Yearbook of Paediatric Endocrinology

Front Endocrinol (Lausanne). 2020; 11: 558897. https://pubmed.ncbi.nlm.nih.gov/33042019/

This patient cohort study evaluated the prevalence of autoimmune thyroid diseases (AITDs), defined as decreased thyroid echogenicity in 61 children with Crohn’s disease, 25 infliximab (IFX)-naïve (control group) and 36 IFX-treated patients (mean duration of IFX therapy 13.9±16.6 months). The same researcher performed all the thyroid ultrasound scans. In doubtful cases, a second specialist performed a verification scan. AITD prevalence was found higher in IFX-naive patients (7/25) compared to IFX-treated patients (1/36). Thyroid function tests were normal and thyroid autoantibodies were negative in all patients of both groups.

Tumor necrosis factor alpha (TNF-alpha) plays a role in the pathogenesis of autoimmune diseases. Therefore, anti-TNF-alpha agents, such as infliximab (IFX) used in Crohn’s disease, could theoretically modify the outcome of concurrent autoimmune diseases or even protect against them. A higher prevalence of AITD in ulcerative colitis patients has been suggested, but no association with Crohn’s disease. According to published data, the prevalence of thyroid dysfunction is similar or lower in Crohn’s disease patients, compared to the general population (1).

Limitations of this study are the small sample size and the definition of AITD. Actually, while it is true that the lack of autoantibodies does not exclude an AITD, most patients with AITD show high autoantibody titres. Differently from what the authors state, presented data do not seem sufficient to extrapolate a protective role of IFX on the development of autoimmune thyroiditis. The reason why a higher prevalence of decreased thyroid echogenicity is found in IFX-naïve patients than IFX-treated patients, despite the shorter disease duration in the former (mean CD duration: 25 versus 53 months), remains unclear.

Reference: 1. Bernstein CN, Wajda A, Blanchard JF. The clustering of other chronic inflammatory diseases in inflammatory bowel disease: a population-based study. Gastroenterology. 2005; 129: 827–36.