[Plasma metanephrine measurements make the diagnosis of pheochromocytoma easier]

A study where plasma metanephrine and normetanephrine concentrations in 51 patients with hypertension and 62 healthy normotensives were compared with those in 52 patients with histologically confirmed phaeochromocytoma showed measurement of the two variables to constitute a test that reliably excludes the presence of phaeochromocytoma in cases where both values are normal. Other currently available tests (e.g., plasma catecholamine assay) can yield false-negative results in some patients with the tumour, and thus do not reliably exclude its presence in unaffected patients. Accordingly, as a missed diagnosis can have disastrous consequences for the patient, hitherto the exclusion of phaeochromocytoma has typically entailed multiple and repeated tests which are time-consuming and costly. The advantage of the plasma metanephrine-normetanephrine test is that, as it does not yield false-negative results, a negative test result reliably excludes the presence of phaeochromocytoma in suspected cases, and no further tests are necessary.