Inflammatory bowel disease severity and activity are correlated to thyroid gland nodularity, chronic nonthyroidal illness, and thyroid autoantibodies but not thyroid dysfunction

Introduction
An association between inflammatory bowel disease (IBD) and autoimmune thyroid disease (AITD) exists. The aim of the present study was to evaluate thyroid nodules, function, and antibodies in patients with IBD.
Patients and materials
The study included 50 patients with established diagnosis of IBD either ulcerative colitis (UC) or Crohn’s disease and 25 healthy controls. They were classified into two groups: group I included 25 patients with UC, and group II included 25 patients with Crohn’s disease; the control group included 25 healthy individuals. They were subjected to history taking, complete physical examination, and laboratory investigations that included evaluation of erythrocyte sedimentation rate (ESR), C-reactive protein, fecal calprotectin, free T3, free T4, thyroid-stimulating hormone, antithyroid peroxidase (TPO), antithyroglobulin (TG), and TSH receptor antibodies. Ileocolonoscopic and histopathological examination with assessment of IBD activity and thyroid ultrasonography were carried out.
Results
There were no statistically significant differences between the three groups as regards anti-TG antibodies (P=0.075), anti-TPO (P=0.190), AITD assessed serologically or by means of ultrasound (P=1.000), or as regards thyroid status (P=0.528). IBD patients had significantly more thyroid nodules compared with controls (P<0.001), and there was a positive correlation between IBD markers of activity (ESR and fecal calprotectin) and the presence of nodules. A significant negative correlation existed between free T3 and fecal calprotectin, ESR, and C-reactive protein, as well as between free T4 and ESR and fecal calprotectin. A significant positive correlation between anti-TG antibodies and fecal calprotectin as well as between anti-TPO antibodies and histological activity assessment of UC patients also existed. We found a significant negative correlation between free T3 and free T4 and several indices of IBD activity/severity.
Conclusion
AITD and altered thyroid function were the same among IBD patients and controls. However, IBD patients had significantly more nodules; indices of activity/severity of IBD correlated negatively with free T3 and T4, and positively with anti-TPO, anti-TG, and nodularity.