title: The role of urinary fractionated metanephrines in the diagnosis of phaeochromocytoma.
abstract: OBJECTIVE
  Plasma and urinary metanephrines are used as screening tests for the diagnosis of phaeochromocytoma. The recommended cut-off levels are not standardized. This study was conducted to identify a cut-off level for 24 h urinary fractionated metanephrines viz. metanephrine (uMN) and normetanephrine (uNMN) using enzyme immunoassay for the diagnosis of phaeochromocytoma.
  
  
  METHODS
  Consecutive patients suspected to have phaeochromocytoma were included in the study. uMN and uNMN in 24 h urinary sample were measured using a commercial ELISA kit.
  
  
  RESULTS
  Overall, 72 patients were included over a period of 18 months. Twenty patients had histopathologically confirmed phaeochromocytoma and in 52 patients phaeochromocytoma was ruled out. Using the upper limit of normal stated by the assay manufacturer as the cut-off, uMN >350 μg/day had a low sensitivity and uNMN >600 μg/day had a poor specificity. By increasing the cut-off value of uNMN to twice the upper limit, specificity increased significantly without much loss in sensitivity. Combining uMN and uNMN using a cut-off twice the upper limit improved the diagnostic performance - sensitivity (95%); specificity (92.3%); positive predictive value (PPV - 82.6%); negative predictive value (NPV - 98%). In subsets of patients with a variable pretest probability for phaeochromocytoma, the PPV correlates well with the occurred of these tumors decreased, while the NPV remained at 100 per cent.
  
  
  CONCLUSIONS
  ELISA is a simple and reliable method for measuring uMN and uNMN. The test has a good NPV and can be used as an initial screening test for ruling out phaeochromocytoma. Each hospital will have to define the cut-off value for the assay being used, choosing a proper control population.
authors.affiliation: Department of Endocrinology, Christian Medical College, Vellore, India.
authors.forename: Kanakamani
authors.initials: K
authors.lastname: Jeyaraman
authors.forename: Vasanthi
authors.initials: V
authors.lastname: Natarajan
authors.forename: Nihal
authors.initials: N
authors.lastname: Thomas
authors.forename: Paul Mazhuvanchary
authors.initials: PM
authors.lastname: Jacob
authors.forename: Aravindan
authors.initials: A
authors.lastname: Nair
authors.forename: Nylla
authors.initials: N
authors.lastname: Shanthly
authors.forename: Regi
authors.initials: R
authors.lastname: Oommen
authors.forename: Gracy
authors.initials: G
authors.lastname: Varghese
authors.forename: Fleming Jude
authors.initials: FJ
authors.lastname: Joseph
authors.forename: Mandalam Subramaniam
authors.initials: MS
authors.lastname: Seshadri
authors.forename: Simon
authors.initials: S
authors.lastname: Rajaratnam
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000097:blood / Q000652:urine*; D000328:Adult; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008676:Metanephrine / Q000097:blood / Q000652:urine*; D008875:Middle Aged; D009647:Normetanephrine / Q000097:blood / Q000652:urine*; D010673:Pheochromocytoma / Q000097:blood / Q000652:urine*; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D009647:Normetanephrine; D008676:Metanephrine
references.citation: Clin Endocrinol (Oxf). 2007 May;66(5):703-8
references.pmid: 17388796
references.citation: Curr Hypertens Rep. 2002 Jun;4(3):250-5
references.pmid: 12003709
references.citation: Eur J Endocrinol. 2009 Jul;161(1):131-40
references.pmid: 19383804
references.citation: Horm Metab Res. 2009 Sep;41(9):676-9
references.pmid: 19557670
references.citation: J Clin Endocrinol Metab. 2007 Dec;92(12):4602-8
references.pmid: 17635948
references.citation: Ann N Y Acad Sci. 2002 Sep;970:29-40
references.pmid: 12381539
references.citation: Clin Chem. 2001 Jun;47(6):988-9
references.pmid: 11375282
references.citation: Clin Lab Med. 2004 Mar;24(1):85-103
references.pmid: 15157558
references.citation: Clin Chem. 1999 Dec;45(12):2216-23
references.pmid: 10585355
references.citation: Rev Endocr Metab Disord. 2001 Aug;2(3):297-311
references.pmid: 11708294
references.citation: J Clin Endocrinol Metab. 2003 Feb;88(2):553-8
references.pmid: 12574179
references.citation: Eur J Endocrinol. 2006 Mar;154(3):409-17
references.pmid: 16498054
references.citation: JAMA. 2002 Mar 20;287(11):1427-34
references.pmid: 11903030
references.citation: Exp Clin Endocrinol Diabetes. 2012 Sep;120(8):494-500
references.pmid: 22696168
references.citation: Endocr Pract. 2012 Sep-Oct;18(5):694-9
references.pmid: 22982790
references.citation: Clin Biochem Rev. 2009 Feb;30(1):3-17
references.pmid: 19224007
references.citation: Clin Chem. 2006 Nov;52(11):2060-4
references.pmid: 16990424
references.citation: J Clin Endocrinol Metab. 2009 Aug;94(8):2841-9
references.pmid: 19567530
references.citation: Eur J Endocrinol. 2010 May;162(5):951-60
references.pmid: 20142367
references.citation: BMC Endocr Disord. 2004 Jun 29;4(1):2
references.pmid: 15225350