Clinics (Aug 2006)
Prevalence of chronic autoimmune thyroiditis in the urban area neighboring a petrochemical complex and a control area in Sao Paulo, Brazil Prevalência de tireoidite de Hashimoto na população vicinal ao Pólo Petroquímico de Capuava (área Polo) e área controle (São Bernardo Campo) na região metropolitana da grande São Paulo, Brasil
Abstract
PURPOSE: To evaluate the prevalence of chronic autoimmune thyroiditis in 2 urban areas of metropolitan São Paulo (Brazil): Polo Area neighboring a large petrochemical complex and São Bernardo Campo Area (control area). SUBJECTS AND METHODS: Subjects were randomly included from the adult population (20 to 70 years of age) of both genders (women 80%, men 20%) who voluntarily agreed to participate. From the Polo Area, in the vicinity of a large petrochemical industrial complex, 409 subjects were included; from the control area (São Bernardo Campo Area) 420 individuals were included. All subjects were clinically examined, and a detailed record of past thyroid illness and medications was obtained. Ultrasonographic studies were performed using a portable GE Medical Systems apparatus. Blood samples were obtained for free T4, serum TSH, and serum anti-thyroid peroxidase autoantibodies. Urine specimens were collected in Monovette syringes for assaying iodine content. Salt samples were collected at households, and the iodine content was measured. RESULTS: Chronic autoimmune thyroiditis was diagnosed both echographically (marked hypoechogenicity) and immunologically (presence of autoantibodies against thyroid peroxidase). In the Polo Area, 15.6% of the examined population had chronic autoimmune thyroiditis, and in the control area (São Bernardo Campo Area), 19.5% of the population had evidence of chronic autoimmune thyroiditis (P > 0.057, not significant). The prevalence of hypothyroidism was 4.9% in the Polo Area and 8.3% in the São Bernardo Campo Area (P = 0.0461 significant). Taking the 2 populations together, 6.6% had hypothyroidism (about one third of these patients were on L-T4 treatment). The mean thyroid volume was 11.2 mL. Domestic salt had a normal concentration of iodine (35.5 + 6.61 mg/kg). Urinary excretion of iodine was above 300 µg Iodine/L in 58.5% of the total population. CONCLUSION: The high iodine intake (above 300 µg Iodine/L of urine) that was present from 1998 through 2005 may be related to a higher prevalence of chronic autoimmune thyroiditis in both areas that were studied. There was no apparent or documented relationship of chronic autoimmune thyroiditis prevalence to the proximity to the petrochemical complex.OBJETIVO: Analisar a prevalência populacional de tireoidite crônica autoimune (tireoidite de Hashimoto) na área vicinal ao Polo Petroquímico de Capuava comparativamente a área controle em São Bernardo Campo. CASUÍSTICA E MÉTODOS: Em ambas as áreas urbanas foram incluídos, aleatoriamente, indivíduos adultos que, de forma voluntária, concordaram em participar do estudo, estratificado por idade (20 a > 70 anos) e sexo (mulheres 80%, homens 20%). Na área Polo foram incluídos 409 indivíduos e na área controle (São Bernardo Campo) 420 pessoas (sem diferenças significativas quanto a idade e sexo). Na área Polo 15,6% apresentava sinais ecográficos e de positividade para anticorpos anti TPO, confirmando tireoidite crônica autoimune (TCA) comparativamente a 19,5% na área controle (p > 0,05, NS). A presença de hipotiroidismo foi confirmada em 4,9% da população na área Polo e 8,3% na área controle (São Bernardo Campo) (p = 0,046, significativo). No conjunto 6,63% dos pacientes com TCA apresentavam hipofunção tireóidea. A excreção urinária de iodo ultrapassou 300 mcg Iodo/L de urina em 58,5% de ambas populações. O sal coletado nas casas dos examinados apresentava concentração normal de iodo (35,5 + 6,6 mg I/Kg de sal). CONCLUSÕES: A maior prevalência de tireoidite crônica autoimune em ambas as áreas é, provavelmente, decorrente da elevada ingestão nutricional de iodo durante o quinqüênio que precedeu esta pesquisa (1998-2004). A suposta conexão epidemiológica de maior prevalência epidemiológica de TCA com vicinidade com o Polo Petroquímico de Capuava é improvável.
Keywords
