title: Autoimmune thyroiditis in antinuclear antibody positive children without rheumatologic disease.
abstract: BACKGROUND
  Children are commonly referred to a pediatric rheumatology center for the laboratory finding of an Anti-nuclear antibody (ANA) of undetermined significance. Previous studies regarding adult rheumatology patients have supported an association between ANA and anti-thyroid antibodies, with the prevalence of thyroid antibodies being significantly higher in patients referred to a rheumatology center for an ANA without evidence of connective tissue disease compared to the general population. The purpose of the present study was to determine the frequency of thyroid antibodies in children referred to a pediatric rheumatology center for a positive ANA without evidence of a connective tissue disease.
  
  
  METHODS
  A retrospective chart review was performed on children who were referred to our pediatric rheumatology center between August 2003 and March 2007 for positive ANA with concurrent thyroid antibody and thyroid function tests performed who did not fulfill criteria for a specific connective tissue disease. Laboratory and clinical features were recorded and analyzed. Mean and standard deviation were used to describe continuous data. Chi-square or Fisher's exact tests were used to compare proportions between variables.
  
  
  RESULTS
  One-hundred and four ANA-positive patients with concurrent thyroid studies were evaluated (88% female, 93% Caucasian, mean age 11.9 +/- 4.0 years). Half of patients had an ANA titer >/= 1:320. The ANA pattern was speckled in 60% of the patients. Thyroid antibodies were detected in 30% of the patients. Anti-Thyroglobulin (ATG) was detected in 29% and Anti-thyroid peroxidase (ATPO) in 21% of the patients; of these children, 14% had hypothyroidism. ANA pattern and titer were not associated with anti-thyroid antibody positivity.
  
  
  CONCLUSIONS
  Thyroid antibodies associated with chronic lymphocytic thyroiditis, ATG and ATPO, were detected significantly higher in ANA-positive children without a rheumatologic condition (30%) as compared to the general pediatric population (1.3 - 3.4%). ANA titer and pattern did not help predict the presence or absence of thyroid antibodies. Given the high frequency of thyroid antibodies and increased risk of developing hypothyroidism over time, routine evaluation of ATG and ATPO with thyroid function tests in ANA-positive children is recommended.
authors.affiliation: University of Pittsburgh, Children's Hospital of Pittsburgh, Department of Pediatrics, Division of Rheumatology, Pittsburgh, Pennsylvania, USA. Kathryn.Torok@chp.edu.
authors.forename: Kathryn S
authors.initials: KS
authors.lastname: Torok
authors.forename: Thaschawee
authors.initials: T
authors.lastname: Arkachaisri
references.citation: Pediatrics. 1992 Mar;89(3):441-4
references.pmid: 1741219
references.citation: J Pediatr. 1985 Dec;107(6):898-904
references.pmid: 3840842
references.citation: BMC Pediatr. 2004 Jul 09;4:13
references.pmid: 15245579
references.citation: Am J Med. 1991 Oct;91(4):363-70
references.pmid: 1951380
references.citation: N Engl J Med. 1996 Jul 11;335(2):99-107
references.pmid: 8649497
references.citation: Autoimmunity. 2008 Mar;41(2):163-73
references.pmid: 18324486
references.citation: Pediatrics. 1995 Jun;95(6):892-5
references.pmid: 7761217
references.citation: Eur J Endocrinol. 2003 Mar;148(3):301-7
references.pmid: 12611610
references.citation: J Rheumatol. 1991 Oct;18(10):1529-31
references.pmid: 1765977
references.citation: J Rheumatol. 1998 May;25(5):886-91
references.pmid: 9598885
references.citation: J Rheumatol. 1989 Jun;16(6):782-5
references.pmid: 2789286
references.citation: J Rheumatol. 1997 Mar;24(3):576-8
references.pmid: 9058668
references.citation: J Clin Endocrinol Metab. 1988 Mar;66(3):485-8
references.pmid: 3280586
references.citation: Thyroid. 2001 Sep;11(9):849-57
references.pmid: 11575854