title: The diagnostic efficacy of urinary fractionated metanephrines measured by tandem mass spectrometry in detection of pheochromocytoma.
abstract: BACKGROUND
  There are limitations to currently available biochemical tests for pheochromocytoma. Our objective was to evaluate the diagnostic efficacy of a novel tandem mass spectrometry assay for the measurement of fractionated urinary metanephrines in patients suspected to have a pheochromocytoma. We also developed clinically based cut-offs for positivity of this measurement.
  
  
  METHODS
  We examined the medical records of 506 patients (including 102 patients with a catecholamine-producing tumour) who underwent measurement of 24-h urinary fractionated metanephrines using tandem mass spectrometry as well as adrenal imaging at Mayo Clinic, Rochester. The cut-offs for positivity were defined as follows: total metanephrines (sum of the metanephrine fractions) 5163 nmol/day, normetanephrine fraction 4001 nmol/day, metanephrine fraction 1531 nmol/day. Receiver operating characteristic (ROC) curves were constructed.
  
  
  RESULTS
  The diagnostic efficacy was as follows: normetanephrine fraction sensitivity 87.3% [(95% confidence interval (CI) 79.4-92.4%], specificity 95.0% (92.5-96.8); metanephrine fraction sensitivity 56.9% (47.2-66.1), specificity 95.0% (92.5-96.8); elevation of either normetanephrine or metanephrine fraction sensitivity 97.1% (91.7-99.0) and specificity 91.1% (87.9-93.5). Areas under the ROC curves (AUCs) were 0.972 (95% CI 0.955-0.990) for the normetanephrine fraction, 0.800 (0.741-0.858) for the metanephrine fraction, 0.991 (0.985-0.996) for total metanephrines, and 0.991 (0.985-0.996) for a regression-derived ROC curve incorporating both the metanephrine and normetanephrine fractions.
  
  
  CONCLUSIONS
  Measurement of 24-h urinary fractionated metanephrines by a tandem mass spectrometry assay appears to be an effective biochemical technique in the investigation of pheochromocytoma.
authors: Division of Cardiovascular and Medical Sciences, University of Glasgow, UK.
authors: C G
authors: CG
authors: Perry
authors: A M
authors: AM
authors: Sawka
authors: R
authors: R
authors: Singh
authors: L
authors: L
authors: Thabane
authors: J
authors: J
authors: Bajnarek
authors: W F
authors: WF
authors: Young
mesh_terms: D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000652:urine; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000652:urine*; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008676:Metanephrine / Q000652:urine*; D008875:Middle Aged; D009647:Normetanephrine / Q000652:urine; D010673:Pheochromocytoma / Q000175:diagnosis* / Q000652:urine; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor; D009647:Normetanephrine; D008676:Metanephrine