title: Higher free thyroxine levels are associated with frailty in older men: the Health In Men Study.
abstract: OBJECTIVE
  Frailty is common in the elderly and predisposes to ill-health. Some symptoms of frailty overlap those of thyroid dysfunction, but it is unclear whether differences in thyroid status influence risk of frailty. We evaluated associations between thyroid status and frailty in older men.
  
  
  METHODS
  Cross-sectional epidemiological study.
  
  
  METHODS
  Community-dwelling men aged 70-89 years.
  
  
  METHODS
  Circulating thyrotropin (TSH) and free thyroxine (FT(4) ) were assayed. Frailty was assessed as ≥3 of the Fatigue, Resistance, Ambulation, Illnesses and Loss (FRAIL) scale's 5 domains: fatigue; resistance (difficulty climbing flight of stairs); ambulation (difficulty walking 100 m); illness (>5); or weight loss (>5%), blinded to hormone results.
  
  
  RESULTS
  Of 3943 men, 27 had subclinical hyperthyroidism, 431 subclinical hypothyroidism and 608 were classified as being frail (15·4%). There was an inverse log-linear association of TSH with FT(4). There was no association between TSH and frailty. After adjusting for covariates, men with FT(4) in the highest two quartiles had increased odds of being frail (Q3:Q1, odds ratio [OR] = 1·32, 95% confidence interval [CI] = 1·01-1·73 and Q4:Q1, OR = 1·36, 95% CI = 1·04-1·79, P = 0·010 for trend). Higher FT(4) was associated with fatigue (P = 0·038) and weight loss (P < 0·001). The association between FT(4) and frailty remained significant when the analysis was restricted to euthyroid men.
  
  
  CONCLUSIONS
  High-normal FT(4) level is an independent predictor of frailty among ageing men. This suggests that even within the euthyroid range, circulating thyroxine may contribute to reduced physical capability. Further studies are needed to clarify the utility of thyroid function testing and the feasibility of preventing or reversing frailty in older men.
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Western Australia, Australia. byeap@cyllene.uwa.edu.au
authors.forename: Bu B
authors.initials: BB
authors.lastname: Yeap
authors.forename: Helman
authors.initials: H
authors.lastname: Alfonso
authors.forename: Stephen A Paul
authors.initials: SA
authors.lastname: Chubb
authors.forename: John P
authors.initials: JP
authors.lastname: Walsh
authors.forename: Graeme J
authors.initials: GJ
authors.lastname: Hankey
authors.forename: Osvaldo P
authors.initials: OP
authors.lastname: Almeida
authors.forename: Leon
authors.initials: L
authors.lastname: Flicker
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D016330:Frail Elderly / Q000523:psychology / Q000706:statistics & numerical data*; D015577:Geriatric Assessment / Q000379:methods / Q000706:statistics & numerical data*; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000175:diagnosis; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D011795:Surveys and Questionnaires; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood*
chemical_list: D013972:Thyrotropin; D013974:Thyroxine