THYROID HORMONES AND THE REGULATION OF THYROID FUNCTION IN MEN WITH COELIAC DISEASE

A specific pattern of thyroid hormone abnormalities was observed in twenty-seven men with coeliac disease which differed from that observed in patients with non-thyroidal illness (NTI). Serum free thyroxine (FT4) was reduced, but increased after gluten was withdrawn from the diet and jejunal morphology improved. Total T4 (TT4), total triodothyronine (TT3), free triiodothyronine (FT3) and reverse T3 (rT3) levels were unchanged, unlike the findings in nineteen men with Crohn's disease when TT3 fell, rT3 tended to rise but TT4, FT4 and FT3 levels were normal, except FT4 was significantly higher in a subgroup of patients who were more severely ill. The thyroid hormone changes in Crohn's disease are those expected in NTI. Basal serum thyrotrophin (TSH) was normal in all but one of the patients with coeliac disease but 45% of untreated coeliacs had exaggerated responses of TSH to thyrotrophin releasing hormone, an observation which cannot be explained as a feature of NTI. These changes in thyroid hormones in coeliac disease could not be attributed to abnormalities of thyroxine-binding globulin or thyroxine-binding prealbumin, and thyroid autoantibodies were not detected in these patients. Hence, different patterns of thyroid hormone abnormalities can occur in different diseases of the same organ in patients of equivalent nutritional status. Circulating gluten peptides may be involved in the hypothalamic-pituitary disturbance of coeliac disease.