BACKGROUND: The diagnosis of phaeochromocytoma is commonly performed by the measurements of plasma-free normetanephrine and metanephrine. Plasma-deconjugated normetanephrine and metanephrine have been proposed as alternative, equivalent, but easier to measure biomarkers. OBJECTIVE: The aim of this study was to compare the diagnostic performance of plasma-free vs deconjugated normetanephrine and metanephrine in patients tested for phaeochromocytoma. METHODS: The study population included a reference group of 262 normotensive and hypertensive volunteers, 198 patients with phaeochromocytoma and 528 patients initially suspected of having the tumour, but with negative investigations after at least 2 years of follow-up. Measurements were performed using liquid chromatography with electrochemical detection. RESULTS: Plasma concentrations of free normetanephrine were 17-fold higher in patients with phaeochromocytoma than in the reference population, a 72% larger (P < 0·001) difference than that for the 10-fold higher levels of plasma-deconjugated normetanephrine. In contrast, relative increases in plasma concentrations of free and deconjugated metanephrine were similar. Using upper cut-offs established in the reference population, measurements of plasma-free metabolites provided superior diagnostic performance than deconjugated metabolites according to measures of both sensitivity (97% vs 92%, P = 0·002) and specificity (93% vs 89%, P = 0·012). The area under the receiver operating characteristic curve for the free metabolites was larger than that for the deconjugated metabolites (0·986 vs 0·965, P < 0·001). CONCLUSION: Measurements of plasma-free normetanephrine and metanephrine are superior to the deconjugated metabolites for diagnosis of phaeochromocytoma.
BACKGROUND: The diagnosis of phaeochromocytoma is commonly performed by the measurements of plasma-free normetanephrine and metanephrine. Plasma-deconjugated normetanephrine and metanephrine have been proposed as alternative, equivalent, but easier to measure biomarkers. OBJECTIVE: The aim of this study was to compare the diagnostic performance of plasma-free vs deconjugated normetanephrine and metanephrine in patients tested for phaeochromocytoma. METHODS: The study population included a reference group of 262 normotensive and hypertensive volunteers, 198 patients with phaeochromocytoma and 528 patients initially suspected of having the tumour, but with negative investigations after at least 2 years of follow-up. Measurements were performed using liquid chromatography with electrochemical detection. RESULTS: Plasma concentrations of free normetanephrine were 17-fold higher in patients with phaeochromocytoma than in the reference population, a 72% larger (P < 0·001) difference than that for the 10-fold higher levels of plasma-deconjugated normetanephrine. In contrast, relative increases in plasma concentrations of free and deconjugated metanephrine were similar. Using upper cut-offs established in the reference population, measurements of plasma-free metabolites provided superior diagnostic performance than deconjugated metabolites according to measures of both sensitivity (97% vs 92%, P = 0·002) and specificity (93% vs 89%, P = 0·012). The area under the receiver operating characteristic curve for the free metabolites was larger than that for the deconjugated metabolites (0·986 vs 0·965, P < 0·001). CONCLUSION: Measurements of plasma-free normetanephrine and metanephrine are superior to the deconjugated metabolites for diagnosis of phaeochromocytoma.
Authors: Jacques W M Lenders; Karel Pacak; McClellan M Walther; W Marston Linehan; Massimo Mannelli; Peter Friberg; Harry R Keiser; David S Goldstein; Graeme Eisenhofer Journal: JAMA Date: 2002-03-20 Impact factor: 56.272
Authors: R Dajani; A Cleasby; M Neu; A J Wonacott; H Jhoti; A M Hood; S Modi; A Hersey; J Taskinen; R M Cooke; G R Manchee; M W Coughtrie Journal: J Biol Chem Date: 1999-12-31 Impact factor: 5.157
Authors: Ivana Jochmanova; April Melody T Abcede; Ruby Jane S Guerrero; Chandy Lou P Malong; Robert Wesley; Thanh Huynh; Melissa K Gonzales; Katherine I Wolf; Abhishek Jha; Marianne Knue; Tamara Prodanov; Naris Nilubol; Leilani B Mercado-Asis; Constantine A Stratakis; Karel Pacak Journal: J Cancer Res Clin Oncol Date: 2020-02-15 Impact factor: 4.553