Autoimmune thyroid diseases (AITD) are the main causes of thyroid dysfunction and the most common autoimmune diseases in the world. An association between AITD and infections with the human immunodeficiency virus (HIV), in combination with the effects of highly active antiretroviral therapy (HAART), has been suggested by several research groups. The aim of the present study was to evaluate the frequency of thyroid dysfunction and AITD in women > 35 years of age infected with HIV, and to identify factors associated with the emergence of these thyroid abnormalities. HIV-infected women (n = 153) selected from the infectious disease outpatient clinic at a University Hospital in Rio de Janeiro were characterized based on their circulating CD4 + lymphocytes levels, viral loads, serum TSH levels, and the presence of FT4 and anti-thyroperoxidase antibodies (TPO-Ab). A total of 129 participants were on HAART and 24 were not. The frequency of thyroid disorders was 7.8% (12/153 patients) and all were on HAART at the time of diagnosis, yielding a prevalence of 9.3% in patients receiving HAART compared with 0% in patients not on HAART. AITD, hyper, and hypothyroidism were detected in 4.6%, 3.1%, and 4.1% of HAART patients. It was not detected any thyroid dysfunction or autoimmunity in HIVinfected women not on HAART. This study demonstrated an association between HAART and the development of AITD. In addition AITD only developed in HAART patients also presenting with undetectable viral loads and slightly elevated CD4 + T cell counts. Arq Bras Endocrinol Metab. 2013;57(6):450-6Keywords Autoimmune thyroid disease; thyroid dysfunction; hypothyroidism; hyperthyroidism; HIV; anti-retroviral therapy; immunity RESUMO Doenças tiroidianas autoimunes (DTAI) são a maior causa de disfunção tiroidiana e são as doenças autoimunes mais comuns no mundo. A associação entre DTAI e infecções com o vírus da imunodeficiência humana (HIV), em combinação com a terapia antirretroviral altamente ativa (HAART), foi sugerida por vários grupos de pesquisadores. O objetivo do presente estudo foi avaliar a frequência de disfunção tiroidiana e DTAI em mulheres com mais 35 anos de idade infectadas com o HIV e identificar fatores associados com a emergência dessas anormalidades tiroidianas. As mulheres infectadas com HIV (n = 153), selecionadas do ambulatório de doenças infecciosas de um hospital universitário do Rio de Janeiro, foram caracterizadas com base no nível de linfócitos CD4 + circulantes, carga viral, níveis de TSH sérico e presença de anticorpos FT4 e antitiroperoxidase (TPO-Ab). Um total de 129 participantes se tratava com HAART e 24 não. A frequência de desordens da tiroide foi 7,8% (12/153 pacientes) e todas estavam em tratamento com HAART no momento do diagnóstico, levando a uma prevalência 9,3% em pacientes recebendo HAART, em comparação com 0% em pacientes não tratadas com HAART. DTAI, hipertireoidismo e hipotireoidismo foram detectados em 4,6%, 3,1% e 4,1% das pacientes tratadas com HAART. Não foram detectadas disfunção tiroidiana ...