title: Hashimoto's thyroiditis: relative recurrence risk ratio and implications for screening of first-degree relatives.
abstract: BACKGROUND
  The relative recurrence risk ratio (λR) for Hashimoto's thyroiditis (HT) has not been widely studied. The age at which thyroid function evaluation should be initiated for relatives of HT patients remains unclear.
  
  
  OBJECTIVE
  To study λRand age-related prevalence of HT in first-degree relatives of HT patients.
  
  
  METHODS
  First-degree relatives (n = 861) of 264 HT patients were evaluated for goitre, thyroid function tests, thyroid antibodies (TAb) and urinary iodide concentration (UIC). HT was defined as TAb positivity and hypothyroidism (subclinical/overt). λRwas calculated as {number of index patients whose relatives (of particular subtype) had HT/number of index patients having relatives of same subtype}÷ population prevalence of HT (5·1%). The age-related prevalence of HT was studied using Kaplan-Meier method.
  
  
  RESULTS
  A total of 861 relatives (205 parents, 336 siblings and 320 offspring) participated in the study. About 38·3% were TAb positive. The prevalence of HT was 16·7% (22·9% in parents, 19·6% in siblings and 9·6% in offspring). TAb positivity (48·3% vs 33·1%) and HT (23·5% vs 13·6%) were significantly more common in the goitrous group (n = 267) vs nongoitrous group. The median UIC for the study population was 182·5 μg/l. Computed λRwas 9·1 for any one relative being affected, 5·9 for parents, 6·3 for siblings and 3·1 for offspring. The prevalence of HT increased with age and exceeded the adult population prevalence of 5·1% at 20 years in females and 27 years in males.
  
  
  CONCLUSIONS
  Relatives of HT patients have a ninefold increased risk for developing HT as compared to the general population. The risk of developing HT exceeds that of the general population at 20 years in females and 27 years in males.
authors.affiliation: Department of Endocrinology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Nikita
authors.initials: N
authors.lastname: Bothra
authors.affiliation: Department of Endocrinology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Nalini
authors.initials: N
authors.lastname: Shah
authors.affiliation: Department of Endocrinology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Manjunath
authors.identifier: http://orcid.org/0000-0001-7679-6656
authors.initials: M
authors.lastname: Goroshi
authors.affiliation: Department of Endocrinology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Swati
authors.initials: S
authors.lastname: Jadhav
authors.affiliation: Department of Radiology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Sheetal
authors.initials: S
authors.lastname: Padalkar
authors.affiliation: Department of Radiology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Hemangini
authors.initials: H
authors.lastname: Thakkar
authors.affiliation: Scientist-'G' & Head (Nutrition), Indian Council of Medical Research, Department of Health Research, Ministry of Health & Family Welfare, Govt. of India, New Delhi, India.
authors.forename: Gurudayal Singh
authors.initials: GS
authors.lastname: Toteja
authors.affiliation: Department of Endocrinology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Vyankatesh
authors.initials: V
authors.lastname: Shivane
authors.affiliation: Department of Endocrinology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Anurag
authors.initials: A
authors.lastname: Lila
authors.affiliation: Department of Endocrinology, Seth GSMC and KEM Hospital, Mumbai, India.
authors.forename: Tushar
authors.initials: T
authors.lastname: Bandgar
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000906:Antibodies / Q000097:blood; D002648:Child; D004198:Disease Susceptibility; D005192:Family Health; D005260:Female; D050031:Hashimoto Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D006801:Humans; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D012008:Recurrence; D012737:Sex Factors; D013961:Thyroid Gland / Q000276:immunology; D055815:Young Adult
chemical_list: D000906:Antibodies