title: Changes in thyroid function with age: results from the Pizarra population-based longitudinal study.
abstract: BACKGROUND
  Results of studies examining the influence of age on thyroid function and TSH levels, in the absence of thyroid disease, remain controversial. The aim of this study was to determine the course of thyroid function over 11 years in a population with normal thyroid function.
  
  
  METHODS
  This is a population-based prospective study started in 1995-1997 (first phase), and reassessed 6 (second phase) and 11 years later (third phase).
  
  
  RESULTS
  The TSH and FT4 in the third phase were significantly increased (p=0.001 and p=0.001, respectively), with the values being higher particularly from the age of 50 years. In those persons with a baseline TSH≥1.2 and <3 μIU/mL, the OR of having a TSH of 3-5 μIU/mL in the third phase was 6.10 (p=0.004). In those with a baseline TSH≥3 and ≤5 μIU/mL, the OR of having a TSH of 3-5 μIU/mL in the third phase was 20.8 (p<0.0001). Similar results were found for FT4.
  
  
  CONCLUSIONS
  In a population free of clinical thyroid disease, TSH and FT4 values rise over the years. This increase occurs in all age groups, but depends mainly on the basal concentrations of TSH and FT4.
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: A Ma
authors.initials: AM
authors.lastname: Lago-Sampedro
authors.forename: C
authors.initials: C
authors.lastname: Gutiérrez-Repiso
authors.forename: S
authors.initials: S
authors.lastname: Valdés
authors.forename: C
authors.initials: C
authors.lastname: Maldonado
authors.forename: N
authors.initials: N
authors.lastname: Colomo
authors.forename: M C
authors.initials: MC
authors.lastname: Almaraz
authors.forename: E
authors.initials: E
authors.lastname: Rubio-Martín
authors.forename: S
authors.initials: S
authors.lastname: Morcillo
authors.forename: I
authors.initials: I
authors.lastname: Esteva
authors.forename: M S
authors.initials: MS
authors.lastname: Ruiz de Adana
authors.forename: V
authors.initials: V
authors.lastname: Perez-Valero
authors.forename: F
authors.initials: F
authors.lastname: Soriguer
authors.forename: G
authors.initials: G
authors.lastname: Rojo-Martínez
authors.forename: E
authors.initials: E
authors.lastname: García-Fuentes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013030:Spain; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D055815:Young Adult
chemical_list: D013972:Thyrotropin