title: Low Plasma Klotho Concentrations and Decline of Knee Strength in Older Adults.
abstract: BACKGROUND
  Although the "anti-aging hormone" klotho is associated with sarcopenia in mice, the relationship between klotho and muscle strength in older adults is not well known.
  
  
  METHODS
  Plasma klotho concentrations were measured in 2,734 older adults, aged 71-80 years, who participated in the Health, Aging and Body Composition Study, a prospective observational cohort study conducted in Memphis, TN and Pittsburgh, PA. Knee extension strength was measured using isokinetic dynamometry at baseline and follow-up 2 and 4 years later. Knee extension strength was normalized for weight.
  
  
  RESULTS
  At baseline, participants in the highest tertile of plasma klotho had higher knee extension strength (β = .72, standard error [SE] = .018, p < .0001) compared with those in the lowest tertile in a multivariable linear regression model adjusting for age, sex, race, smoking, study site, C-reactive protein, interleukin-6, and diabetes. Participants in the highest tertile of plasma klotho at baseline had less of a decline in knee strength over 4 years of follow-up (β = -.025, SE = .011, p = .02) compared with those in the lowest tertile in a multivariable linear regression model adjusting for the same covariates above.
  
  
  CONCLUSIONS
  Plasma klotho concentrations were an independent predictor of changes in knee strength over time in older adults. Further studies are needed to identify the biological mechanisms by which circulating klotho could modify skeletal muscle strength.
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland. rdsemba@jhmi.edu.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Semba
authors.affiliation: National Institute on Aging, NIH, Baltimore, Maryland.
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.affiliation: National Institute on Aging, NIH, Baltimore, Maryland.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Simonsick
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Randi
authors.initials: R
authors.lastname: Turner
authors.affiliation: Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania.
authors.forename: Iva
authors.initials: I
authors.lastname: Miljkovic
authors.affiliation: Intramural Research Program, Laboratory of Epidemiology and Population Sciences, National Institute on Aging, NIH, Bethesda, Maryland.
authors.forename: Tamara
authors.initials: T
authors.lastname: Harris
authors.affiliation: Department of Epidemiology and Biostatistics, University of California San Francisco School of Medicine.
authors.forename: Ann V
authors.initials: AV
authors.lastname: Schwartz
authors.affiliation: Department of Preventive Medicine, University of Tennessee, Memphis.
authors.forename: Keiko
authors.initials: K
authors.lastname: Asao
authors.affiliation: Sticht Center on Aging, Wake Forest University, Winston-Salem, North Carolina.
authors.forename: Stephen
authors.initials: S
authors.lastname: Kritchevsky
authors.affiliation: Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001835:Body Weight; D002097:C-Reactive Protein / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D015577:Geriatric Assessment / Q000379:methods; D005966:Glucuronidase / Q000097:blood*; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D000090265:Klotho Proteins; D007717:Knee / Q000503:physiopathology*; D016014:Linear Models; D008297:Male; D053580:Muscle Strength; D053581:Muscle Strength Dynamometer; D010414:Pennsylvania; D011379:Prognosis; D015203:Reproducibility of Results
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6; D002097:C-Reactive Protein; D005966:Glucuronidase; D000090265:Klotho Proteins
keywords: Aging; Klotho; Sarcopenia; Skeletal muscle strength