Lenders JWM, Keiser HR, Goldstein DS, Willemsen JJ, Friberg
P, et al.
Plasma metanephrines in the diagnosis of
Ann Int Med
(Jul) 123:101-109 1995
The purpose of the study was to determine whether plasma metanephrine
measurement offered any advantages over plasma catecholamine or urinary
metanephrine measurements. 52 pts with pheo, 51 pts with essential HTN, and
67 normotensives were studied; compairsons were made to pts with secondary
hypertension or heart disease. All pts with pheo had elevated plasma
metanephrines (100% sensitivity vs. 85% sensitivity for plasma
catecholamines). If used to screen a hypertensive population with a much
lower prevalence of pheo (much less than 1% in most series), more false
positive but few false negative results would be expected.
Plasma free and total metanephrines were measured by HPLC/ED whereas urinary
metanephrines were assayed using a colorimetric assay. Sensititivity was
100% for the plasma assay but only 89% for urine; however, this may be
explained by different techniques employed. False positive plasma tests
occurred in 15% (64% predictive value); The predictive value of the
plasma metanephrine test, i.e.,
percentage of patients with a positive test that truly have the disease,
be even lower, however, if screening hypertensive populations with low
prevalence of pheo.
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