title: Sensitivity and specificity of adenosine deaminase in diagnosis of juvenile idiopathic arthritis.
abstract: BACKGROUND
  Juvenile Idiopathic Arthritis (JIA) is one of the most common chronic rheumatic diseases inchildren with unknown etiology and pathogenesis. It also has no diagnostic test and its clinical diagnosis ismade through ruling out other types of arthritis. The aim of this study was to evaluate the level of ADA (AdenosineDeaminase) in the serum of JIA patients and to compare it with that of patients with Reactive Arthritis(RA). Evaluation of sensitivity and specificity of serum ADA level in JIA was another objective.
  
  
  METHODS
  The study included 120 children with JIA (mean age= 7.6 ± 4.3 years) and 40 children with RA(mean age= 5.5 ± 3.1 years). The ADA was measured in the active phase of both diseases.
  
  
  RESULTS
  The mean ADA serum level was obtained as 15.8 ± 11.8 U/l in JIA patients and 14.3 ± 7.5 U/l in RApatients. The difference was statistically insignificant (p= 0.4). Another finding of this study was the significantspecificity (77.5%) of this laboratory parameter for JIA in comparison with its low sensitivity (36.7%). Positivepredictive value was 83% and negative predictive value 29%.
  
  
  CONCLUSIONS
  Determination of ADA serum levels is a noninvasive reliable and easy biomarker for diagnosis ofJIA and it can be used as alternative parameters representing disease activity.
authors: 1. MD, Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran. mina_doudkani_fard.1387@yahoo.com.
authors: Mina
authors: M
authors: Doudkani-Fard
authors: 2. MD, Pediatric Rheumatology Research Group, Rheumatology Research Center, Tehran University of Medical Sciences and Department of Pediatrics, Tehran University of Medical Sciences, Tehran, Iran. ziaee@tums.ac.ir.
authors: Vahid
authors: V
authors: Ziaee
authors: 3. MD, Department of Pediatrics, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran. mh.moradinejad@gmail.com.
authors: Mohamad-Hassan
authors: MH
authors: Moradinejad
authors: 4. MD, Department of Community Medicine, School of Medicine, Tehran University of Medical Sciences, Iran. sedaghat.dr@gmail.com.
authors: Mojtaba
authors: M
authors: Sedaghat
authors: 5. MD, Department of Pathology, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran. ashtiani20@yahoo.com.
authors: Mohammad-Taghi
authors: MT
authors: Haghi-Ashtiani
authors: 6. MD, Department of Infectious Diseases, Tehran University of Medical Sciences, Tehran, Iran. ahmadiz@tums.ac.ir.
authors: Zahra
authors: Z
authors: Ahmadinejad
keywords: Adenosine deaminase; Children; Chronic arthritis; Juvenile idiopathic arthritis; Reactive arthritis