Endocrine Abstracts

Introduction: Hashimoto’s thyroiditis (HT) is a complex disease which is caused by genetic as well as environmental factors. While the genetic predisposition to HT has been extensively investigated, the influence of most environmental factors still needs to be evaluated. Based on our previous study, we did not find any correlation between HT and the fact of cigarette smoking or the number of pack-years. We did, however, find a significant correlation between the age of smoking discontinuation and the age of HT onset. However, in this previous study, the number of patients for which we have obtained data on smoking discontinuation, was very sparse; therefore, no unequivocal conclusions could have been made.

Aim: The aim of our study was to verify the correlation between the age of smoking discontinuation and HT diagnosis.

Methods: In our first study, we included 35 HT patients who have declared to have stopped smoking in the past. The verification study included 48 patients. Stepwise regression analysis was used to predict the dependence of the age of HT diagnosis with gender, age of smoking discontinuation, TSH at diagnosis, and anti-TPO at diagnosis.

Results: In patients who had discontinued smoking at the age of 39 years or more, the diagnosis of HT was predominantly made after the discontinuation of smoking. No such regularity was observed for patients who had stopped smoking before the age of 39 years. In their case, the diagnosis of HT was made similarly often before and after the discontinuation of smoking. The patients’ gender and biochemical parameters at diagnosis were not significantly correlated with the age of HT onset.

Conclusions: We concluded that neither smoking nor its discontinuation has a significant impact on the onset of HT symptoms in patients aged less than 39 years before smoking discontinuation. However, in the vast majority of our HT patients who had stopped smoking at a later timepoint, it seemed as if stopping smoking was a trigger of HT symptoms that would be indicative of the disease. It remains to be evaluated whether this is a straight-forward correlation or whether other factors like hormonal changes or the ability to deal with stress in the older patients might have been involved in the observed correlation.