title: Hemoglobin levels and skeletal muscle: results from the InCHIANTI study.
abstract: BACKGROUND
  Anemia is associated with reduced physical performance and muscle strength. The aim of the study was to explore whether anemia and hemoglobin levels are associated with differences in quantitative and qualitative measures of muscle and fat.
  
  
  METHODS
  The study sample consisted of 909 participants 65 years and older enrolled in the "Invecchiare in Chianti" (InCHIANTI) study, a prospective population-based study of older people aimed at identifying risk factors for late-life disability. All the analyses were performed considering continuous hemoglobin levels as well as the dichotomous anemia variable (defined according to World Health Organization criteria as hemoglobin <12 g/dL in women and <13 g/dL in men). A peripheral quantitative computed tomography (pQCT) scan was performed in all participants to evaluate total, muscular, and fat cross-sectional areas of the calf and relative muscle density. Ankle extension strength was measured using a hand-held dynamometer. Linear regression analyses were used to assess the multivariate relationship of pQCT and skeletal muscle strength measures with hemoglobin levels and anemia after adjustment for demographics, chronic conditions, medication use, and other biological variables.
  
  
  RESULTS
  Participants were aged 74.8 +/- 6.8 years. In our sample, 94 participants (10.3%) were anemic. Hemoglobin levels were significantly associated with muscle density (beta = 0.225 [SE, standard error 0.098], p=.02), muscle area/total area ratio (beta=0.778 [SE 0.262], p=.003), fat area/total area ratio (beta=-0.869 [SE 0.225]; p<.001). Skeletal muscle strength and muscle density were highly associated with anemia (beta=-3.266 [SE 1.173], p=.005 and beta=-0.816 [SE 0.374], p=.03, respectively). Results did not change when analyses were rerun in a restricted sample of participants not affected by major medical conditions.
  
  
  CONCLUSIONS
  The present study shows that hemoglobin levels are associated with the parameters of body composition obtained by pQCT, and that decreases in muscular strength measures occur in the presence of anemia.
authors.affiliation: Sticht Center on Aging, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA. mcesari@wfubmc.edu
authors.forename: Matteo
authors.initials: M
authors.lastname: Cesari
authors.forename: Brenda W J H
authors.initials: BW
authors.lastname: Penninx
authors.forename: Fulvio
authors.initials: F
authors.lastname: Lauretani
authors.forename: Cosimo R
authors.initials: CR
authors.lastname: Russo
authors.forename: Christy
authors.initials: C
authors.lastname: Carter
authors.forename: Stefania
authors.initials: S
authors.lastname: Bandinelli
authors.forename: Hal
authors.initials: H
authors.lastname: Atkinson
authors.forename: Graziano
authors.initials: G
authors.lastname: Onder
authors.forename: Marco
authors.initials: M
authors.lastname: Pahor
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000097:blood / Q000503:physiopathology; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007558:Italy; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed
chemical_list: D006454:Hemoglobins