RESUMO
Sensitive and specific radioimmunoassays of metanephrine and normetanephrine were developed by use of 125I-labeled synephrine and specific metanephrine antibody, and 125I-labeled octopamine and specific normetanephrine antibody. Specific antibody for both metanephrine and normetanephrine was raised in rabbits by immunization with bovine serum albumin conjugated with the corresponding hapten, prepared by the method of Grota and Brown (Endocrinology 1976;98:615). The detection limits of the metanephrine and the normetanephrine radioimmunoassays were 2 and 6 pg/tube, respectively. Mean plasma metanephrine and normetanephrine values for 24 normal subjects were 62 (SD 14) and 100 (SD 40) ng/L, respectively. Mean urinary metanephrine and normetanephrine values for 22 normal subjects were 154 (SD 74) and 217 (SD 109) micrograms/day. For 14 pheochromocytoma patients, plasma metanephrine and normetanephrine values ranged from 29 to 683 and from 28 to 7850 ng/L, and urinary metanephrine and normetanephrine values were 606 to 6630 and 296 to 4800 micrograms/day, respectively. The present methods are simple and suitable for routine tests or for mass screening for pheochromocytoma.
Assuntos
Neoplasias das Glândulas Suprarrenais/metabolismo , Epinefrina/análogos & derivados , Metanefrina/análise , Normetanefrina/análise , Feocromocitoma/metabolismo , Especificidade de Anticorpos , Humanos , Soros Imunes/imunologia , Radioisótopos do Iodo , Metanefrina/imunologia , Normetanefrina/imunologia , Octopamina/imunologia , Radioimunoensaio/normas , Valores de Referência , Sinefrina/imunologiaRESUMO
The haptens p-tyramine and synephrine were conjugated to bovine serum albumin by means of the formaldehyde condensation reaction. These conjugates were emulsified in adjuvant and injected into rabbits. Antiserum was harvested at 10-day intervals after booster injections. The anti-sera were screened by immunodiffusion. After detecting the presence of antibody, an antiserum was further characterized by antiserum dilution curves, standard curves, and cross-reactivity studies using labeled p-tyramine or labeled metanephrine. The cross-reactivity studies indicated that the antisera to either hapten had low affinity to compounds with structural deviations on the side chain or ring other than at the position ortho to the phenolic hydroxyl group. The antisera were more sensitive to 3-methyoxylated compounds (3-methody-tyramine and metanephrine) than to 3-hydroxy or unsubstituted compounds.
