title: Serum bicarbonate and bone mineral density in US adults.
abstract: BACKGROUND
  Chronic metabolic acidosis leads to bone mineral loss and results in lower bone mineral density (BMD), which is a risk factor for osteoporosis-related fractures. The effect of low-level metabolic acidosis on bone density in the general population is unknown.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  9,724 nationally representative adults 20 years or older in NHANES (National Health and Nutrition Examination Survey) 1999-2004.
  
  
  METHODS
  Serum bicarbonate level.
  
  
  RESULTS
  Lumbar and total BMD, as well as low lumbar and total bone mass, defined as 1.0 SD below the sex-specific mean value of young adults.
  
  
  METHODS
  BMD was measured by dual-energy x-ray absorptiometry and serum bicarbonate was measured in all participants.
  
  
  RESULTS
  Both men and women with lower serum bicarbonate levels were more likely to be current smokers and had higher body mass index and estimated net endogenous acid production. There was a significant linear trend across quartiles of serum bicarbonate with lumbar BMD in the total population, as well as in sex-specific models (P=0.02 for all 3 models, P=0.1 for interaction). For total BMD, a significant association was seen with serum bicarbonate level for women but not men (P=0.02 and P=0.1, respectively; P=0.8 for interaction), and a significant association was seen for postmenopausal women but not premenopausal women (P=0.02 and P=0.2, respectively; P=0.5 for interaction). Compared with women with serum bicarbonate levels <24mEq/L, those with serum bicarbonate levels ≥27mEq/L had 0.018-g/cm(2) higher total BMD (95% CI, 0.004-0.032; P=0.01) and 31% lower odds of having low total bone mass (OR, 0.68; 95% CI, 0.46-0.99; P=0.049).
  
  
  CONCLUSIONS
  Cross-sectional study using a single measurement of serum bicarbonate. Subgroup differences are not definitive.
  
  
  CONCLUSIONS
  Lower serum bicarbonate levels are associated with lower BMD in US adults. Further studies should examine whether serum bicarbonate levels should be incorporated into the diagnostic assessment and management of osteoporosis.
authors.affiliation: Division of Nephrology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY. Electronic address: wei_chen@urmc.rochester.edu.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Division of Nephrology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY; Department of Epidemiology & Population Health, Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Michal L
authors.initials: ML
authors.lastname: Melamed
authors.affiliation: Division of Nephrology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY; Department of Epidemiology & Population Health, Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Abramowitz
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D001639:Bicarbonates / Q000097:blood*; D015519:Bone Density / Q000187:drug effects / Q000502:physiology*; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D003430:Cross-Sectional Studies; D004164:Diphosphonates / Q000494:pharmacology; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys / Q000379:methods; D014481:United States / Q000453:epidemiology
chemical_list: D001639:Bicarbonates; D050071:Bone Density Conservation Agents; D004164:Diphosphonates
keywords: National Health and Nutrition Examination Survey (NHANES); Serum bicarbonate; alkali therapy; bone mineral density (BMD); dual-energy x-ray absorptiometry (DEXA); low bone mass; lumbar BMD; metabolic acidosis; modifiable risk factor; osteoporosis