DAVID C. ARON, M.D.; EMMANUEL L. BRAVO, M.D.; LEONARD P. KAPCALA, M.D.
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To the editor: The measurement of plasma norepinephrine and the use of the clonidine suppression test have facilitated the differentiation between patients with pheochromocytoma and those with essential hypertension and signs or symptoms suggestive of pheochromocytoma (1, 2). We recently noted discordant results between the levels obtained by radioimmunoassay (Nichols Institute) and by radioenzymatic assay (1).
A 45-year-old man was suspected of having a pheochromocytoma because of labile hypertension associated with anxiety and sweating attacks. His 24-hour urinary catecholamine level was 148 µg (normal, < 100 µg); and his vanillylmandelic acid level was 8.5 mg (normal, < 7 mg). A
ARON DC, BRAVO EL, KAPCALA LP. Erroneous Plasma Norepinephrine Levels with Radioimmunoassay. Ann Intern Med. ;98:1023. doi: 10.7326/0003-4819-98-6-1023_2
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Published: Ann Intern Med. 1983;98(6):1023.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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