title: The association between bone turnover markers and kyphosis in community-dwelling older adults.
abstract: OBJECTIVE
  Hyperkyphosis, accentuated curvature of the thoracic spine, is often attributed to osteoporosis, yet its underlying pathophysiology is not well understood. Bone turnover markers (BTM) reflect the dynamic process of bone formation and resorption. This study examined the association between serum BTM levels and kyphosis in community-dwelling older adults.
  
  
  METHODS
  Between 2003 and 2006, 760 men and women in the Rancho Bernardo Study age 60 and older had blood drawn and kyphosis measured. Fasting serum was assayed for N-telopeptide (NTX) and procollagen type 1 n-terminal propeptide (P1NP), markers of bone resorption and formation, respectively. Participants requiring two or more 1.7 cm blocks under their head to achieve a neutral supine position were classified as having accentuated kyphosis. Analyses were stratified by sex and use of estrogen therapy (ET). Odds of accentuated kyphosis were calculated for each standard deviation increase in log-transformed BTM.
  
  
  RESULTS
  Mean age was 75 years. Overall, 51% of 341 non-ET using women, 41% of 111 ET-using women, and 75% of 308 men had accentuated kyphosis. In adjusted models, higher P1NP and NTX were associated with decreased odds of accentuated kyphosis in non-ET using women (P1NP: OR = 0.78 [95% CI, 0.58-0.92]; NTX: OR = 0.68 [95% CI, 0.54-0.86]), but not in men or ET-using women (p> 0.05).
  
  
  CONCLUSIONS
  The selective association of higher bone turnover with reduced odds of accentuated kyphosis in non-ET using women suggests that elevated BTM were associated with a lower likelihood of hyperkyphosis only in the low estrogen/high BTM environment characteristic of postmenopausal women who are not using ET.
authors.affiliation: San Diego State University/University of California, San Diego Joint Doctoral Program in Public Health (Epidemiology), 9500 Gilman Drive, MC 0725, La Jolla, CA 92093, United States.
authors.forename: Corinne R
authors.initials: CR
authors.lastname: McDaniels-Davidson
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego School of Medicine, San Diego, CA, United States.
authors.forename: Donna
authors.initials: D
authors.lastname: Kritz-Silverstein
authors.affiliation: Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, United States.
authors.forename: Mei-Hua
authors.initials: MH
authors.lastname: Huang
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego School of Medicine, San Diego, CA, United States.
authors.forename: Gail A
authors.initials: GA
authors.lastname: Laughlin
authors.affiliation: SPD Development Company Limited, Bedford, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Johnson
authors.affiliation: JouZeNet Consulting Limited, Kempele, Finland.
authors.forename: Jouko
authors.initials: J
authors.lastname: Haapalahti
authors.affiliation: 4BoneHealth, La Jolla, CA, United States.
authors.forename: Diane L
authors.initials: DL
authors.lastname: Schneider
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego School of Medicine, San Diego, CA, United States.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Barrett-Connor
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego School of Medicine, San Diego, CA, United States.
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Kado
keywords: BTM, bone turnover markers; Bone remodeling; Bone turnover; ET, estrogen therapy; Hyperkyphosis; Kyphosis; NTX; NTX, N-telopeptide; P1NP; P1NP, procollagen type 1 n-terminal propeptide; SOF, Study of Osteoporotic Fractures