Is There Seasonality in Hypothyroidism? A Google Trends Pilot Study

Introduction: There may be seasonality in thyroid diseases and internet search data may provide information on disease patterns. In this study we used data from internet searches on hypothyroidism to assess seasonality in this disease. Methods: We collected worldwide data, as well as data for countries in the southern hemisphere (Brazil, South Africa, and Australia), covering 15 years, from Google Trends with the search term “hypothyroidism+thyroiditis (the commonest cause of hypothyroidism)” and “fatigue+weakness (the commonest symptoms of hypothyroidism)”. We looked for periodicity in relevant internet searches by calculating autocorrelations; we also looked at the cross-correlation of internet searches for “hypothyroidism+thyroiditis” and “fatigue+weakness” and we compared the results by season with the Kruskall-Wallis test. Results: There was periodicity in the relevant internet searches and strong cross-correlations between internet searches for “hypothyroidism+thyroiditis” and “fatigue+weakness” worldwide and for South Africa and Australia. In both the northern and the southern hemispheres there were significantly more hypothyroidism-related internet searches during spring (p<0.05). Conclusion: Hypothyroidism was more popular in internet searches at springtime in the northern and the southern hemispheres. Thus, although this analysis is coarse, it seems that some seasonality can be inferred on hypothyroidism, taking into account the limitations of our approach.