Pheochromocytoma catecholamine phenotypes and prediction of tumor size and location by use of plasma free metanephrines.
BACKGROUND
Measurements of plasma free metanephrines (normetanephrine and metanephrine) provide a useful test for diagnosis of pheochromocytoma and may provide other information about the nature of these tumors.


METHODS
We examined relationships of tumor size, location, and catecholamine content with plasma and urinary metanephrines or catecholamines in 275 patients with pheochromocytoma. We then prospectively examined whether measurements of plasma free metanephrines could predict tumor size and location in an additional 16 patients.


RESULTS
Relative proportions of epinephrine and norepinephrine in tumor tissue were closely matched by relative increases of plasma or urinary metanephrine and normetanephrine, but not by epinephrine and norepinephrine. Tumor diameter showed strong positive relationships with summed plasma concentrations or urinary outputs of metanephrine and normetanephrine (r = 0.81 and 0.77; P <0.001), whereas relationships with plasma or urinary catecholamines were weaker (r = 0.41 and 0.44). All tumors in which increases in plasma metanephrine were >15% of the combined increases of normetanephrine and metanephrine either had adrenal locations or appeared to be recurrences of previously resected adrenal tumors. Measurements of plasma free metanephrines predicted tumor diameter to within a mean of 30% of actual diameter, and high plasma concentrations of free metanephrine relative to normetanephrine accurately predicted adrenal locations.


CONCLUSIONS
Measurements of plasma free metanephrines not only provide information about the likely presence or absence of a pheochromocytoma, but when a tumor is present, can also help predict tumor size and location. This additional information may be useful for clinical decision-making during tumor localization procedures.
Eisenhofer
Graeme
G
Clinical Neurocardiology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892-1620, USA. ge@box-g.nih.gov
Lenders
Jacques W M
JW
Goldstein
David S
DS
Mannelli
Massimo
M
Csako
Gyorgy
G
Walther
McClellan M
MM
Brouwers
Frederieke M
FM
Pacak
Karel
K
D000310:Adrenal Gland Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D002395:Catecholamines / Q000032:analysis* / Q000097:blood / Q000652:urine; D006801:Humans; D008676:Metanephrine / Q000097:blood* / Q000652:urine; D009647:Normetanephrine / Q000097:blood* / Q000652:urine; D010641:Phenotype; D010673:Pheochromocytoma / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D010949:Plasma; D011446:Prospective Studies; D012016:Reference Values; D012680:Sensitivity and Specificity
D002395:Catecholamines; D009647:Normetanephrine; D008676:Metanephrine