Prevalence of thyroid disorders among older people: results from the São Paulo Ageing & Health Study Prevalência de doenças da tireóide em idosos: resultados do São Paulo Ageing & Health Study

This study aimed to estimate prevalence of thyroid disorders in the São Paulo Ageing & Health Study, an epidemiological study addressing several health-adverse outcomes among elderly people living in a poor area of São Paulo, Brazil. All participants answered a questionnaire and had a blood sample collected to assess levels of tireotropic hormone and free-thyroxine. Among 1,373 people (60.8% women), prevalence rates (95% confidence interval) for thyroid dysfunction (%) were: overt hyperthyroidism, 0.7% (0.2-1.1) [women: 0.8% (0.2-1.5); men: 0.4% (0.01-0.9)]; overt hypothyroidism, 5.7% (4.5-6.9) [women: 5.9% (4.3-7.5); men: 5.4% (3.5-7.3)]; subclinical hyperthyroidism, 2.4% (1.6-3.2) [women: 2.8% (1.6-3.9); men: 1.9% (0.7-3.0)]; and subclinical hypothyroidism, 6.5% (5.2-7.8) [women: 6.7% (5.08.4); men: 6.1% (4.1-8.2)]. There was no difference in prevalence rates according to gender, but almost 40% of women were diagnosed and under treatment compared to 9% of men. The burden of thyroid disorders in this sample is high and most participants were not aware of them. Thyroid Diseases; Aged; Hyperthyroidism; Hypothyroidism Introduction Thyroid diseases are frequent in older individuals, and symptoms of hypothyroidism such as tiredness, fatigue, lack of concentration or dry skin can be very similar to complaints associated to ageing 1,2. Even for hyperthyroidism, clinical presentation in elderly people is much more silent when compared to middle-aged people 3. Beyond symptoms associated with thyroid disorders, epidemiologic studies have shown a possible association between subclinical and overt thyroid disorders and cardiovascular disease 3,4,5,6. A review published by the American College of Physicians estimated for population studies a pooled prevalence of overt hypothyroidism in women ≥ 70 years of 2% and in men ≥ 60 years of 0.8%. For overt hyperthyroidism, the numbers were 0.6% for women ≥ 60 years and 0.1% for men ≥ 60 years 7. Based on these data, some authors 8,9, have recommended screening for thyroid disorders especially in elderly people but this is not the view expressed in position papers from both the US Preventive Services Task Force 10 and the Canadian Task Force 11. However, among older people with unspecified complaints, to rule out thyroid dysfunction is always a dilemma considering that only one third of cases show typical signs and symptoms of the disease, and treatment is cost effective 12. ARTIGO ARTICLE Benseñor IM et al. 156 Cad. Saúde Pública, Rio de Janeiro, 27(1):155-161, jan, 2011 The present study addresses the prevalence of thyroid disorders in a population-based sample of low-income elderly people living in São Paulo, Brazil.