title: Iodine deficiency and thyroid nodular pathology--epidemiological and cancer characteristics in different populations: Portugal and South Africa.
abstract: BACKGROUND
  The prevalence and pathology pattern of iodine deficiency (ID) related disorders are influenced by the dietary iodine intake: low iodine leads to thyroid nodular enlargement, to an increase in the incidence of thyroid cancer, an increase in anaplastic carcinomas and to an alteration in the papillary to follicular neoplasia ratio. This study aims at highlighting the effects of ID by comparatively evaluating the pattern of thyroid nodular pathology in different populations that, although geographically distant and heterogeneous, both had iodine deficiency at the time of data gathering and are at high altitude: Beira Interior (BI) in Portugal and Johannesburg (JHB) in South Africa. (S.A.) Mandatory salt iodization introduced in S. A. in 1995 has recently been shown to have resulted in the correction of ID.
  
  
  METHODS
  Evaluation of thyroid histology reports over a 6 year period in BI and a 5 year period in the JHB area.
  
  
  RESULTS
  Region of BI: 278 patients with histology reports-60 were malignancies (21.2 %): 31 papillary carcinomas, 22 follicular cancers (18 follicular carcinomas and 4 Hürthle cell tumours), 3 medullary carcinomas and 4 anaplastic carcinomas. Region of JHB: 136 histology reports- 33 were malignancies (24.3 %): 13 papillary carcinomas, 15 follicular cancers (10 follicular carcinomas and 5 Hürthle cell tumours), 1 medullary carcinoma, 3 anaplastic carcinomas and 1 metastatic carcinoma into the thyroid. There was an overlap in the frequencies of all histology types, of particular relevance in the relatively high anaplastic carcinoma incidences and in the papillary to follicular carcinoma ratios which was close to 1 in both areas- BI area ratio: 1.4 and JHB area ratio: 0.87, with overlapping 95 % CI's, also confirmed by the results of the chi-square calculations.
  
  
  CONCLUSIONS
  During the study periods evaluated both study areas displayed pathology patterns usually found in ID. Public information regarding the negative consequences of ID combined with the availability of affordable iodized salt are likely to achieve the goal of the elimination of ID. Sea based nutrition, (naturally iodine containing), may also contribute to the elimination of ID, particularly at times when salt restriction tends to be generally advised.
authors.affiliation: Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal. endosantos@hotmail.com.|CICS-UBI Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal. endosantos@hotmail.com.|Centro Hospitalar Cova da Beira, Covilhã, Portugal. endosantos@hotmail.com.
authors.forename: José Eduardo Carvalho
authors.initials: JE
authors.lastname: Santos
authors.affiliation: Department of Endocrinology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. jhkalk@yahoo.com.
authors.forename: William John
authors.initials: WJ
authors.lastname: Kalk
authors.affiliation: Centro Hospitalar Cova da Beira, Covilhã, Portugal. mfreitas@fcsaude.ubi.pt.|Department of Biostatistics, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal. mfreitas@fcsaude.ubi.pt.
authors.forename: Miguel
authors.initials: M
authors.lastname: Freitas
authors.affiliation: CIMAGO-Centre of Investigation in Environment, Genetics and Oncobiology, Coimbra, Portugal. icarreira@fmed.uc.pt.
authors.forename: Isabel
authors.initials: I
authors.lastname: Marques Carreira
authors.affiliation: Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal. mcbranco@fcsaude.ubi.pt.|CICS-UBI Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal. mcbranco@fcsaude.ubi.pt.|Centro Hospitalar Cova da Beira, Covilhã, Portugal. mcbranco@fcsaude.ubi.pt.
authors.forename: Miguel
authors.initials: M
authors.lastname: Castelo Branco
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control; D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control; D018276:Carcinoma, Medullary / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control; D018278:Carcinoma, Neuroendocrine / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control; D002291:Carcinoma, Papillary / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control; D005260:Female; D006042:Goiter / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D007455:Iodine / Q000172:deficiency* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D017673:Sodium Chloride, Dietary / Q000627:therapeutic use; D013019:South Africa / Q000453:epidemiology; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control
chemical_list: D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine