title: Spot urinary 5-hydroxyindoleacetic acid is not an ideal diagnostic test for acute appendicitis.
abstract: OBJECTIVE
  There is growing evidence to suggest the use of urinary 5-hydroxyindoleacetic acid (5-HIAA) test to help with the diagnosis of appendicitis. The aim of our study was to establish whether urinary 5-HIAA could be used as an effective diagnostic test for acute appendicitis.
  
  
  METHODS
  A prospective double-blinded study was carried out from December 2014 to October 2015. Patients admitted to the emergency surgical ward of a teaching hospital with suspected appendicitis were included in the study. The diagnostic accuracy of the test was measured by receiver operating characteristic curve.
  
  
  RESULTS
  Ninety-seven patients were divided into 2 groups: acute appendicitis (n=38) and other diagnosis (n=59). The median value of urinary 5-HIAA was 24.19μmol/L (range, 5.39-138.27) for acute appendicitis vs 18.87μmol/L (range, 2.27-120.59) for other diagnosis group (P=.038). The sensitivity and specificity of urinary 5-HIAA at a cutoff value of 19μmol/L were 71% and 50%, respectively. Receiver operating characteristic analysis showed that the area under curve was 0.64 (confidence interval [CI], 0.513-0.737) for urinary 5-HIAA, which was lower than white blood cell count (0.69; CI, 0.574-0.797), neutrophil count (0.68; CI, 0.565-0.792), and C-reactive protein (0.76; CI, 0.657-0.857). There was no significant difference in the median values of 5-HIAA between different grades of severity of appendicitis (P=.704).
  
  
  CONCLUSIONS
  Urinary 5-HIAA is not an ideal test for the diagnosis of acute appendicitis.
authors.affiliation: Department of Surgery, Ninewells Hospital and Medical School, Dundee DD2 9SY, UK. Electronic address: a.rao@imperial.ac.uk.
authors.forename: Ahsan
authors.initials: A
authors.lastname: Rao
authors.affiliation: Department of Surgery, Ninewells Hospital and Medical School, Dundee DD2 9SY, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Wilson
authors.affiliation: Immunoassay Biomarker Core Laboratory, School of Medicine, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
authors.forename: Gwen
authors.initials: G
authors.lastname: Kennedy
authors.affiliation: Department of Surgery, Ninewells Hospital and Medical School, Dundee DD2 9SY, UK.
authors.forename: Devender
authors.initials: D
authors.lastname: Mittapalli
authors.affiliation: Department of Surgery, Ninewells Hospital and Medical School, Dundee DD2 9SY, UK.
authors.forename: Iain
authors.initials: I
authors.lastname: Tait
authors.affiliation: Department of Surgery, Ninewells Hospital and Medical School, Dundee DD2 9SY, UK.
authors.forename: Afshin
authors.initials: A
authors.lastname: Alijani
mesh_terms: D015746:Abdominal Pain / Q000175:diagnosis / Q000652:urine; D000328:Adult; D001064:Appendicitis / Q000175:diagnosis / Q000652:urine*; D019540:Area Under Curve; D016022:Case-Control Studies; D003248:Constipation / Q000175:diagnosis / Q000652:urine; D004311:Double-Blind Method; D005260:Female; D005759:Gastroenteritis / Q000175:diagnosis / Q000652:urine; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000652:urine*; D008297:Male; D010048:Ovarian Cysts / Q000175:diagnosis / Q000652:urine; D011446:Prospective Studies; D012372:ROC Curve; D056844:Renal Colic / Q000175:diagnosis / Q000652:urine; D012422:Rupture, Spontaneous / Q000175:diagnosis / Q000652:urine; D012680:Sensitivity and Specificity; D014552:Urinary Tract Infections / Q000175:diagnosis / Q000652:urine
chemical_list: D006897:Hydroxyindoleacetic Acid