title: Arterialized venous bicarbonate is associated with lower bone mineral density and an increased rate of bone loss in older men and women.
abstract: BACKGROUND
  Higher dietary net acid loads have been associated with increased bone resorption, reduced bone mineral density (BMD), and increased fracture risk.
  
  
  OBJECTIVE
  The objective was to compare bicarbonate (HCO3) measured in arterialized venous blood samples to skeletal outcomes.
  
  
  METHODS
  Arterialized venous samples collected from participants in the Health, Aging and Body Composition (Health ABC) Study were compared to BMD and rate of bone loss.
  
  
  METHODS
  The setting was a community-based observational cohort.
  
  
  METHODS
  A total of 2287 men and women age 74 ± 3 years participated.
  
  
  METHODS
  Arterialized venous blood was obtained at the year 3 study visit and analyzed for pH and pCO2. HCO3 was determined using the Henderson-Hasselbalch equation.
  
  
  METHODS
  BMD was measured at the hip by dual-energy x-ray absorptiometry at the year 1 (baseline) and year 3 study visits.
  
  
  RESULTS
  Plasma HCO3 was positively associated with BMD at both year 1 (P = .001) and year 3 (P = .001) in models adjusted for age, race, sex, clinic site, smoking, weight, and estimated glomerular filtration rate. Plasma HCO3 was inversely associated with rate of bone loss at the total hip over the 2.1 ± 0.3 (mean ± SD) years between the two bone density measurements (P < .001). Across quartiles of plasma HCO3, the rate of change in BMD over the 2.1 years ranged from a loss of 0.72%/y in the lowest quartile to a gain of 0.15%/y in the highest quartile of HCO3.
  
  
  CONCLUSIONS
  Arterialized plasma HCO3 was associated positively with cross-sectional BMD and inversely with the rate of bone loss, implying that systemic acid-base status is an important determinant of skeletal health during aging. Ongoing bone loss was linearly related to arterialized HCO3, even after adjustment for age and renal function. Further research in this area may have major public health implications because reducing dietary net acid load is possible through dietary intervention or through supplementation with alkaline potassium compounds.
authors: Division of Endocrinology (L.S.T., D.E.S.), Johns Hopkins Hospital, Johns Hopkins School of Medicine, Baltimore, Maryland 21224; California Pacific Medical Center Research Institute (S.R.C.), San Francisco, California 94118; Department of Preventive Medicine (F.A.T.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; Department of Medicine (D.C.B., A.S.), School of Medicine, University of California, San Francisco, San Francisco, California 94143; Department of Epidemiology (J.A.C., A.N.), Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15260; Department of Internal Medicine (S.B.K.), Wake Forest School of Medicine, Winston-Salem, North Carolina 27157; Translational Gerontology Branch (E.M.S.), National Institute on Aging, Baltimore, Maryland 21224; and Laboratory of Epidemiology and Population Science (T.B.H.), National Institute on Aging, Bethesda, Maryland 20892.
authors: L S
authors: LS
authors: Tabatabai
authors: S R
authors: SR
authors: Cummings
authors: F A
authors: FA
authors: Tylavsky
authors: D C
authors: DC
authors: Bauer
authors: J A
authors: JA
authors: Cauley
authors: S B
authors: SB
authors: Kritchevsky
authors: A
authors: A
authors: Newman
authors: E M
authors: EM
authors: Simonsick
authors: T B
authors: TB
authors: Harris
authors: A
authors: A
authors: Sebastian
authors: D E
authors: DE
authors: Sellmeyer
mesh_terms: D000368:Aged; D000375:Aging / Q000097:blood / Q000502:physiology*; D001639:Bicarbonates / Q000097:blood*; D001784:Blood Gas Analysis / Q000379:methods; D001823:Body Composition / Q000502:physiology; D015519:Bone Density; D001862:Bone Resorption / Q000097:blood / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010024:Osteoporosis / Q000097:blood* / Q000503:physiopathology
chemical_list: D001639:Bicarbonates
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