title: Effect of micronutrient deficiency on QuantiFERON-TB Gold In-Tube test and tuberculin skin test in diagnosis of childhood intrathoracic tuberculosis.
abstract: OBJECTIVE
  Data on performance of QuantiFERON-TB Gold In-Tube test (QFT) and tuberculin skin test (TST) in children with active tuberculosis from high burden countries in the context of micronutrient deficiency are scarce. The objective of this study was to evaluate the effect of micronutrient deficiency on the performance of TST and QFT in children with intrathoracic tuberculosis.
  
  
  METHODS
  Children with probable intrathoracic tuberculosis underwent TST, QFT, gastric lavages and induced sputum examination for AFB (Acid-Fast Bacilli) smear and culture. Zinc, copper, ferritin and vitamin D were measured on stored serum samples. The study used cross-sectional data at initiation of anti-tubercular therapy.
  
  
  RESULTS
  Three hundred and sixty-two children (median age 115.5 months (interquartile range: 73, 144), 200 (55.3%) girls) were enrolled in the study. Microbiological confirmation of tuberculosis could be obtained in 128 patients. TST and QFT were positive in 337 (93%) and 297 (82%) children, respectively. Performance of both the tests was unaffected by weight-for-age and height-for-age 'z-scores' or by serum copper levels. TST was not affected by serum zinc and ferritin levels. Children with negative QFT results had lower mean serum zinc level (P=0.01) and higher ferritin levels (P=0.007) as compared to those with positive test. Higher proportion of children with positive TST were vitamin D deficient/insufficient (P=0.003).
  
  
  CONCLUSIONS
  Micronutrient status, especially serum levels of zinc, may influence the performance of QFT in children with intrathoracic tuberculosis. Considering the high prevalence of zinc deficiency in developing countries, QFT should be used cautiously for diagnosing tuberculosis.
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: A
authors.initials: A
authors.lastname: Mukherjee
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Saini
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Kabra
authors.affiliation: Department of Endocrinology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: N
authors.initials: N
authors.lastname: Gupta
authors.affiliation: Department of Pediatrics, Kalawati Saran Children Hospital and Lady Hardinge Medical College, New Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Singh
authors.affiliation: Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Bhatnagar
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: D
authors.initials: D
authors.lastname: Saini
authors.affiliation: 1] Department of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway [2] Department of Microbiology, Haukeland University Hospital, Bergen, Norway.
authors.forename: H M S
authors.initials: HM
authors.lastname: Grewal
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: R
authors.initials: R
authors.lastname: Lodha
mesh_terms: D000293:Adolescent; D000995:Antitubercular Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D003300:Copper / Q000097:blood; D003430:Cross-Sectional Studies; D004311:Double-Blind Method; D005260:Female; D005293:Ferritins / Q000097:blood; D006801:Humans; D007194:India; D007223:Infant; D008297:Male; D018977:Micronutrients / Q000008:administration & dosage / Q000172:deficiency*; D015995:Prevalence; D016032:Randomized Controlled Trials as Topic; D014374:Tuberculin Test / Q000379:methods*; D014376:Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy; D014807:Vitamin D / Q000097:blood; D015032:Zinc / Q000097:blood
chemical_list: D000995:Antitubercular Agents; D018977:Micronutrients; D014807:Vitamin D; D003300:Copper; D005293:Ferritins; D015032:Zinc