title: Evolution of urinary iodine excretion over eleven years in an adult population.
abstract: OBJECTIVE
  Few prospective cohort studies have evaluated dietary iodine intake and urinary iodine concentrations in the general adult population. We assess the evolution of urinary iodine excretion and factors that may influence it in an adult population followed for 11 years.
  
  
  METHODS
  A population-based cohort study was undertaken in Pizarra (Spain). In the three study phases (baseline (n = 886), and 6 (n = 788) and 11 years later (n = 501)), participants underwent an interview and a standardized clinical examination that included a food questionnaire, and thyroid hormone and urinary iodine determinations. Subjects with thyroid dysfunction, palpable goiter or urinary iodine excretion >400 μg/L were excluded.
  
  
  RESULTS
  Urinary iodine increased over the years (100.6 ± 70.0 μg/L at baseline vs. 125.4 ± 95.2 μg/L at 6 years and 141.6 ± 81.4 μg/L at 11 years; p < 0.0001). Urinary iodine was significantly higher in subjects who reported iodized salt consumption and in subjects with a higher intake of dairy products (p < 0.05). Consumption of iodized salt (Risk ratio (RR) = 1.23, 95% CI [1.01-2.05]) and dairy products (RR = 2.07, 95% CI [1.01-4.23]), and a baseline urinary iodine concentration ≥100 μg/L (RR = 1.26, 95% CI [1.04-1.53]) were significantly associated with urinary iodine concentrations ≥100 μg/L at 11 years. There is no correlation between thyroid function (TSH, free triiodothyronine or free thyroxine levels) and urinary iodine concentrations in conditions of iodine sufficiency.
  
  
  CONCLUSIONS
  The increase in urinary iodine concentrations over eleven years is associated with an increase in iodized salt intake and with the dairy products intake, and possibly with a higher iodine content of dairy products. However, individual variability in urinary iodine excretion was not fully explained by dietary iodine intake alone; previous urinary iodine concentrations were also important.
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Gutiérrez-Repiso
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Colomo
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain; CIBER de Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Málaga, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Rojo-Martinez
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain; CIBER de Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Málaga, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Valdés
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Tapia
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain; CIBER de Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Málaga, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Esteva
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain; CIBER de Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Málaga, Spain.
authors.forename: Maria S
authors.initials: MS
authors.lastname: Ruiz de Adana
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain.
authors.forename: Elehazara
authors.initials: E
authors.lastname: Rubio-Martin
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Lago-Sampedro
authors.affiliation: Endocrinology and Nutrition Department, Complejo Hospitalario de Jaén, Jaén, Spain.
authors.forename: Piedad
authors.initials: P
authors.lastname: Santiago
authors.affiliation: Unidad de Gestión Clínica Materno-Infantil, Hospital de Riotinto, Huelva, Spain.
authors.forename: Ines
authors.initials: I
authors.lastname: Velasco
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain. Electronic address: edugf1@gmail.com.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Garcia-Fuentes
authors.affiliation: Molecular Thyroid Laboratory, INGEMM-Institute for Medical and Molecular Genetics, La Paz University Hospital, Madrid, Spain.
authors.forename: Jose C
authors.initials: JC
authors.lastname: Moreno
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos IIII, Málaga, Spain; CIBER de Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Málaga, Spain.
authors.forename: Federico
authors.initials: F
authors.lastname: Soriguer
mesh_terms: D000328:Adult; D005075:Biological Evolution; D003611:Dairy Products; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage; D013030:Spain; D013961:Thyroid Gland / Q000378:metabolism; D013974:Thyroxine / Q000378:metabolism; D014284:Triiodothyronine / Q000378:metabolism; D055815:Young Adult
chemical_list: D017673:Sodium Chloride, Dietary; C034024:iodized salt; D014284:Triiodothyronine; D007455:Iodine; D013974:Thyroxine
keywords: Dairy product; Iodized salt; Urinary iodine