Iodine nutritional status in Brazil: a meta-analysis of all studies performed in the country pinpoints to an insufficient evaluation and heterogeneity.
OBJECTIVE
Iodine deficiency disorder (IDD) is the result of an inadequate dietary intake of iodine, which physiological consequences are endemic goiter and thyroid dysfunction. The objective of this study was to a analyze studies that assessed the status of Brazil's population iodine nutrition and IDD prevalence.


METHODS
Systematic review using PRISMA statement. Electronic database: PubMed, Medline, SciELO and Lilacs. Quality of studies: Newcastle-Ottawa Scale. Meta-analysis was carried out with R Core Team Statistical Software, version 3.1.0 (2014). The summary measure (WMD) and its confidence interval (CI) of 95% were calculated. The "Funnel plot" graph assessed publication bias and heterogeneity.


RESULTS
Seventeen papers were eligible: pregnant women (2), school children (9), adults/elderly (4) and preschool children/infants (2). Geographic distribution: North (1), Northeast (1), Midwest (2), Southeast (13), South (3). Twenty-three thousand two hundred seventy-two subjects were evaluated between 1997 and 2013 and all have use urinary iodine (UI) measurement. However, only 7 studies could be included in meta-analysis, all from Southeast region. The overall prevalence of IDD in school children in southeast region was 15.3% (95% CI, 13-35%), however this data had an important heterogeneity, expressed by the I2 Statistic of 99.5%.


CONCLUSIONS
Only few studies have been performed and enrolled populations from south/southeast region of Brazil. The actual IDD prevalence analysis is complex because it was detected bias due influence of individual studies and very high heterogeneity. IDD might still be high in some areas but this remained unknown even after this meta-analysis evaluation. The generation of a national program for analysis of iodine status in all regions is urgently required.
Department of Bioregulation, Health & Science Institute, Universidade Federal da Bahia, Salvador, BA, Brazil.
Renata de Oliveira
Rde O
Campos
Department of Bioregulation, Health & Science Institute, Universidade Federal da Bahia, Salvador, BA, Brazil.
Iasmin dos Santos
Idos S
Barreto
Department of Bioregulation, Health & Science Institute, Universidade Federal da Bahia, Salvador, BA, Brazil.
Lorena Rejane de Jesus
LR
Maia
Department of Bioregulation, Health & Science Institute, Universidade Federal da Bahia, Salvador, BA, Brazil.
Sara Cristina Lima
SC
Rebouças
Department of Bioregulation, Health & Science Institute, Universidade Federal da Bahia, Salvador, BA, Brazil.
Taíse Lima de Oliveira
TL
Cerqueira
Health & Science Center, Universidade Federal do Recôncavo da Bahia, Santo Antonio de Jesus, BA, Brazil.
Clotilde Assis
CA
Oliveira
Department of Statistics, Universidade Estadual de Feira de Santana, Feira de Santana, BA, Brazil.
Carlos Antônio de Souza Teles
CA
Santos
Health & Science Institute, UFBA, Salvador, BA, Brazil.
Carlos Maurício Cardeal
CM
Mendes
Institute of Chemistry, UFBA, Salvador, BA, Brazil.
Leonardo Sena Gomes
LS
Teixeira
Department of Bioregulation, Health & Science Institute, Universidade Federal da Bahia, Salvador, BA, Brazil.
Helton Estrela
HE
Ramos
D000328:Adult; D000368:Aged; D001938:Brazil / Q000453:epidemiology; D002675:Child, Preschool; D005260:Female; D005843:Geography; D006043:Goiter, Endemic / Q000453:epidemiology; D006801:Humans; D007455:Iodine / Q000172:deficiency* / Q000652:urine; D008297:Male; D009752:Nutritional Status; D011153:Population; D011247:Pregnancy; D015995:Prevalence; D017594:Publication Bias; D012959:Socioeconomic Factors
D007455:Iodine