title: The urinary metanephrine-to-creatinine ratio for the diagnosis of pheochromocytoma.
abstract: OBJECTIVE
  To compare the operating characteristics of two tests for diagnosing pheochromocytoma: 1) measurement of the ratio between urinary metanephrine and creatinine levels and 2) measurement of urinary metanephrine levels alone. A second objective was to ascertain the reasons for false-positive test results.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Hypertension referral center.
  
  
  METHODS
  1013 patients referred for hypertension and tested for pheochromocytoma.
  
  
  METHODS
  24-hour urinary levels of metanephrine (measured using liquid chromatography) and creatinine. The presence of pheochromocytoma was confirmed at surgery. In patients with positive test results, the absence of pheochromocytoma was documented by negative results of retests and imaging procedures.
  
  
  RESULTS
  Of 58 patients with increased metanephrine levels or increased metanephrine-to-creatinine ratios, 20 had pheochromocytoma and 38 did not. Of the 38 patients without pheochromocytoma, 15 had high metanephrine levels but normal metanephrine-to-creatinine ratios. The respective operating characteristics of measurement of urinary metanephrine levels and measurement of the metanephrine-to-creatinine ratio were as follows: sensitivity, 95% and 100%; specificity, 98% and 98%; positive predictive value, 46% and 47%; and negative predictive value, 100% and 100%. In 13 of the 23 patients who had a high metanephrine-to-creatinine ratio, various acute events may have caused hypersecretion of catecholamines.
  
  
  CONCLUSIONS
  Measurement of the metanephrine-to-creatinine ratio is a sensitive and specific test for pheochromocytoma. However, acute events may increase urinary metanephrine excretion to the level that occurs with tumors.
authors.affiliation: Hôpital Broussais, Paris, France.
authors.forename: E
authors.initials: E
authors.lastname: Héron
authors.forename: G
authors.initials: G
authors.lastname: Chatellier
authors.forename: E
authors.initials: E
authors.lastname: Billaud
authors.forename: E
authors.initials: E
authors.lastname: Foos
authors.forename: P F
authors.initials: PF
authors.lastname: Plouin
mesh_terms: D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000652:urine; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000652:urine*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006973:Hypertension / Q000209:etiology; D016014:Linear Models; D008297:Male; D008676:Metanephrine / Q000652:urine*; D008875:Middle Aged; D015999:Multivariate Analysis; D010673:Pheochromocytoma / Q000150:complications / Q000175:diagnosis* / Q000652:urine; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D008676:Metanephrine; D003404:Creatinine