title: Consideration of the degree of increase in urine metadrenalines provides superior specificity in the diagnosis of phaeochromocytoma than additional urine catecholamine measurement.
abstract: BACKGROUND
  Measurement of fractionated plasma or urine metadrenalines is the recommended screening test in the diagnosis of phaeochromocytoma, with clinical cut-offs geared towards diagnostic sensitivity. Current practice at Salford Royal Hospital is to add urine catecholamines onto samples with raised urine metadrenalines, with the aim of adding specificity to a diagnosis of phaeochromocytoma.
  
  
  METHODS
  This practice was reviewed by identifying a series of patients with raised urine metadrenalines who had catecholamines reflectively added. A total of 358 samples were identified from 242 patients, of which 228 had urine catecholamines measured.
  
  
  RESULTS
  A diagnosis of 'phaeochromocytoma' (n = 41) or 'no phaeochromocytoma' (n = 90) was obtained in 131 of 228 patients, giving raised urine metadrenalines a positive predictive value for phaeochromocytoma of 31%. The finding of increased urine catecholamines in samples with raised urine metadrenalines increased specificity for phaeochromocytoma to 70%. However, 95% diagnostic specificity for phaeochromocytoma could be achieved by the introduction of a second cut-off for urine metadrenalines geared towards maximizing specificity.
  
  
  CONCLUSIONS
  Consideration of the degree of increase in urine metadrenalines is a superior method of determining the likelihood of phaeochromocytoma than measurement of urine catecholamines.
authors: Department of Clinical Biochemistry, Salford Royal Hospital, Stott Lane, Salford, Manchester M6 8HD, UK. jonathan.scargill@nhs.net
authors: J J
authors: JJ
authors: Scargill
authors: P
authors: P
authors: Reed
authors: J
authors: J
authors: Kane
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000652:urine; D002395:Catecholamines / Q000652:urine*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008297:Male; D008676:Metanephrine / Q000652:urine*; D010673:Pheochromocytoma / Q000175:diagnosis* / Q000652:urine; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D002395:Catecholamines; D008676:Metanephrine