Eisenhofer Graeme, Lenders Jacques W M, Goldstein David S, Mannelli Massimo, Csako Gyorgy, Walther McClellan M, Brouwers Frederieke M, Pacak Karel
Clinical Neurocardiology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892-1620, USA.
Clin Chem. 2005 Apr;51(4):735-44. doi: 10.1373/clinchem.2004.045484. Epub 2005 Feb 17.
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.
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.
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.
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.
血浆游离甲氧基肾上腺素（去甲氧基肾上腺素和甲氧基肾上腺素）的检测为嗜铬细胞瘤的诊断提供了一种有用的检查方法，并且可能提供有关这些肿瘤性质的其他信息。
我们研究了275例嗜铬细胞瘤患者的肿瘤大小、位置和儿茶酚胺含量与血浆及尿中甲氧基肾上腺素或儿茶酚胺之间的关系。然后，我们前瞻性地研究了血浆游离甲氧基肾上腺素的检测是否能够预测另外16例患者的肿瘤大小和位置。
肿瘤组织中肾上腺素和去甲肾上腺素的相对比例与血浆或尿中甲氧基肾上腺素和去甲氧基肾上腺素的相对增加密切匹配，但与肾上腺素和去甲肾上腺素不匹配。肿瘤直径与甲氧基肾上腺素和去甲氧基肾上腺素的血浆总浓度或尿排出量呈强正相关（r = 0.81和0.77；P <0.001），而与血浆或尿儿茶酚胺的相关性较弱（r = 0.41和0.44）。血浆甲氧基肾上腺素增加超过去甲氧基肾上腺素和甲氧基肾上腺素联合增加量15%的所有肿瘤，要么位于肾上腺，要么似乎是先前切除的肾上腺肿瘤的复发。血浆游离甲氧基肾上腺素的检测预测肿瘤直径的误差平均在实际直径的30%以内，相对于去甲氧基肾上腺素而言，血浆游离甲氧基肾上腺素的高浓度准确地预测了肾上腺位置。
血浆游离甲氧基肾上腺素的检测不仅能提供关于嗜铬细胞瘤可能存在与否的信息，而且当肿瘤存在时，还能帮助预测肿瘤大小和位置。这些额外信息可能有助于肿瘤定位过程中的临床决策。
