title: Comparison of free plasma metanephrines enzyme immunoassay with (131)I-MIBG scan in diagnosis of pheochromocytoma.
abstract: Measurement of free plasma metanephrines (metanephrine and normetanephrine), usually performed by high-performance liquid chromatography with electrochemical detection (HPLC-ECD), has been recommended as the single biochemical test of choice for the diagnosis of pheochromocytoma. Alternatively, a widely available, simple means to measure these biomarkers with enzyme immunoassay (EIA) needs to be studied. The aim of this study was to investigate the diagnostic efficacy of such a method in comparison with (131)I-metaiodobenzylguanidine (MIBG) whole body scan (WBS) in patients with pheochromocytoma. We enrolled patients undergoing (131)I-MIBG WBS due to clinical findings suggestive of pheochromocytoma (n = 45), and patients with primary hypertension (n = 36). All subjects had blood tests for free plasma metanephrine (MN) and normetanephrine (NM) with a commercially available EIA kit. WBS was positive in 30 pheochromocytoma patients and negative in 15 refuted ones, with 100% accuracy. The sensitivity, specificity and accuracy of MN and NM in combination (either or both positive) were 96.7%, 86.3% and 90.1%, showing comparable diagnostic performance both to (131)I-MIBG WBS (all p > 0.1), and also to the same markers measured with HPLC-ECD reported in the literature. These results showed that the EIA method may be eligible as an alternative to HPLC-ECD for plasma metanephrine determination in the identification of pheochromocytoma.
authors.affiliation: Department of Nuclear Medicine, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, 200233, China. gaookok@163.com
authors.forename: Yun-Chao
authors.initials: YC
authors.lastname: Gao
authors.forename: Han-Kui
authors.initials: HK
authors.lastname: Lu
authors.forename: Quan-Yong
authors.initials: QY
authors.lastname: Luo
authors.forename: Li-Bo
authors.initials: LB
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Ding
authors.forename: Rui-Sen
authors.initials: RS
authors.lastname: Zhu
mesh_terms: D019797:3-Iodobenzylguanidine; D000310:Adrenal Gland Neoplasms / Q000097:blood / Q000000981:diagnostic imaging*; D000328:Adult; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D008297:Male; D008676:Metanephrine / Q000097:blood*; D008875:Middle Aged; D009647:Normetanephrine / Q000097:blood; D010673:Pheochromocytoma / Q000097:blood / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging
chemical_list: D009647:Normetanephrine; D019797:3-Iodobenzylguanidine; D008676:Metanephrine