Clonidine test for the diagnosis of pheochromocytoma: the usefulness of urinary metanephrine measurements - Mulinari, R A; Zanella, M T; Guerra, E M M; Kohlmann Junior, O; Saad, C I; Andriolo, Adagmar; Carvalho, J G R; Ribeiro, A B (Brazilian Journal of Medical and Biological Research, 1987)