TSH reference range in older adults: a Brazilian study.

OBJECTIVE To establish serum TSH reference values for a population of Brazilian elderly, and to compare them to those found in the adult population. SUBJECTS AND METHODS Healthy volunteers aged 70 to 85 years, without known thyroid disease or risk factors for thyroid dysfunction, who did not use any medication that could potentially interfere with TSH, were selected. Subjects with goiter, palpable thyroid nodules, anti-thyroperoxidase antibodies, or altered free T4 were excluded. The sample consisted of 360 older adults (180 per sex). RESULTS TSH values corresponding to the 2.5th and 97.5th percentile of the sample were 0.2 and 4.62 mIU/L, respectively. TSH > 2.5 mIU/L was seen in 25.26% of the volunteers, > 3 mIU/L in 15.26%, and > 4 mIU/L in 6.1% of them. TSH values were slightly higher than those previously reported for adults (18-60 years). CONCLUSION This study suggests an upper limit for normal TSH of approximately 4.6 mIU/L for the Brazilian elderly population.