title: Phasing-in plasma metanephrines determination.
abstract: OBJECTIVE
  We set up plasma normetanephrine (pNMA) and metanephrine (pMA) assays as they demonstrated their usefulness for diagnosing phaeochromocytomas. Our scope is to describe some practical laboratory aspects and the clinical relevance of these assays in our endocrinological or cardiological departments.
  
  
  METHODS
  We retrospectively reviewed the results of MA from a population of in- and outpatients over a 7-year period. Subjects (n=2536) from endocrinological or cardiological departments were investigated (66 phaeochromocytomas). Urinary NMA (uNMA) and pNMA, and urinary MA (uMA) and pMA were assayed by HPLC with electrochemical detection.
  
  
  RESULTS
  pNMA and pMA assays are now more frequently requested than uNMA and uMA. This changed our laboratory work load with improved delivery, sensitivity and reliability of plasma assays as well as reduced apparatus maintenance time. The pNMA and pMA upper reference limits (URLs) of subjects with no phaeochromocytoma were 1040 and 430 pmol/l respectively. Sensitivity and specificity based on receiver operating characteristic curves optimal points were 83 and 93% for pNMA at 972 pmol/l and 67 and 98% for pMA at 638 pmol/l. Sensitivity and specificity of paired tests of pMA (positive test: at least one analyte above its URLs) were 100 and 91% respectively.
  
  
  CONCLUSIONS
  The very low concentration of analytes requires a sustained very good apparatus analytical sensitivity. This can be obtained in an up-to-date laboratory. In terms of clinical performances, assays in plasma or urine are equivalent. Depending on local preferences, populations, strategies or departments, requests for one or the other assay may sustain the need for specifically defined reference ranges.
authors.affiliation: Department of Nuclear Medicine, CHU de Bordeaux, F-33604 Pessac, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Brossaud
authors.forename: Philippe
authors.initials: P
authors.lastname: Gosse
authors.forename: Blandine
authors.initials: B
authors.lastname: Gatta
authors.forename: Antoine
authors.initials: A
authors.lastname: Tabarin
authors.forename: Guy
authors.initials: G
authors.lastname: Simonnet
authors.forename: Jean-Benoît
authors.initials: JB
authors.lastname: Corcuff
mesh_terms: D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000097:blood*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008676:Metanephrine / Q000097:blood*; D008875:Middle Aged; D009647:Normetanephrine / Q000097:blood*; D010673:Pheochromocytoma / Q000097:blood*; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D009647:Normetanephrine; D008676:Metanephrine