PSEUDOHYPERTHYROXINAEMIA IN CELIAC-DISEASE - REVERSIBILITY WITH GLUTEN-FREE DIET

History: An increased concentration of free T-3 (fT(3)) With normal TS H was repeatedly measured in a 58-year-old man with diarrhoea. Hyperth yreoidism was diagnosed and he was treated with thyrostatic drugs. Inv estigations: Referred to our clinic, fT(4) concentration, determined b y routine ELISA, was found to be raised to 33.9 pmol/l, while fT(3) an d TSH levels were within normal limits. But the equilibrium-dialysis m ethod gave a normal serum level also for fT(4). Gastroscopy suggested coeliac disease, confirmed histologically. Treatment and course: The s ymptoms quickly improved on a gluten-free diet and the fT(4) level ret urned to normal Values even on routine measurement. Conclusion: The ra ised fT(4) level with non-suppressed TSH was only revealed as a false finding by special non-routine laboratory methods. The reversibility a nd the close time relationship of the reported laboratory data with th e clinical manifestations of the concomitant coeliac disease strongly suggested that changes in serum in the course of the latter disease pl ayed a role in these misleading laboratory results. An interference of coeliac disease with some laboratory tests has been previously descri bed.