1. Postgraduation Program in Medicine and Medical Sciences, Federal University of Rio Grande do Sul, 90035-003 Porto Alegre, RS, Brazil
2. Divisão de Medicina Interna, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcellos 2350/700, 90035-903 Porto Alegre, RS, Brazil