title: Associations of homoarginine with bone metabolism and density, muscle strength and mortality: cross-sectional and prospective data from 506 female nursing home patients.
abstract: In female nursing home patients, homoarginine was associated with lower bone turnover, higher bone density, lower mortality and, by trend, with muscle strength.
  
  
  BACKGROUND
  Homoarginine, a cationic amino acid, may be relevant for muscusloskeletal health because it inhibits alkaline phosphatases (AP) and is involved in nitric oxide and energy metabolism. We aimed to evaluate whether homoarginine serum concentrations are associated with bone density and metabolism, muscle strength, fractures and mortality.
  
  
  METHODS
  We examined a cohort of female nursing home patients that underwent quantitative bone ultrasound (QUS) measurements and assessments of knee extensor strength. Measurements of serum homoarginine, C-terminal telopeptide cross-links (β-CTxs) and osteocalcin were also performed at baseline. Thereafter, patients were followed-up with respect to fractures and mortality.
  
  
  RESULTS
  Serum homoarginine concentrations were determined in 506 female study participants (mean age: 83.9 ± 6.0 years). Homoarginine was inversely correlated with β-CTxs (r = -0.26; p < 0.001) and osteocalcin (r = -0.21; p < 0.001), and these associations remained significant in multiple regression analyses. Multivariate regression analyses showed that homoarginine is significantly associated with calcaneus stiffness (beta coefficient = 0.11; p = 0.020) and by trend with knee extensor strength (beta coefficient = 0.09; p = 0.065). During a mean follow-up time of 27 ± 8 months, we recorded 119 deaths (23.5%) and 63 fractures (12.5%). In multivariate analyses, homoarginine was associated with significantly reduced risk of mortality and the combined endpoint of fractures and mortality.
  
  
  CONCLUSIONS
  Whether homoarginine metabolism is critically involved into the pathogenesis of musculoskeletal diseases and fatal events warrants further studies.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology and Metabolism, Medical University of Graz, Auenbruggerplatz 15, 8036, Graz, Austria. stefan.pilz@chello.at
authors.forename: S
authors.initials: S
authors.lastname: Pilz
authors.forename: A
authors.initials: A
authors.lastname: Meinitzer
authors.forename: A
authors.initials: A
authors.lastname: Tomaschitz
authors.forename: K
authors.initials: K
authors.lastname: Kienreich
authors.forename: H
authors.initials: H
authors.lastname: Dobnig
authors.forename: M
authors.initials: M
authors.lastname: Schwarz
authors.forename: D
authors.initials: D
authors.lastname: Wagner
authors.forename: C
authors.initials: C
authors.lastname: Drechsler
authors.forename: C
authors.initials: C
authors.lastname: Piswanger-Sölkner
authors.forename: W
authors.initials: W
authors.lastname: März
authors.forename: A
authors.initials: A
authors.lastname: Fahrleitner-Pammer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001317:Austria / Q000453:epidemiology; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000502:physiology*; D001842:Bone and Bones / Q000378:metabolism*; D002111:Calcaneus / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology; D006707:Homes for the Aged; D006709:Homoarginine / Q000097:blood* / Q000172:deficiency; D006801:Humans; D009026:Mortality; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009735:Nursing Homes; D011379:Prognosis; D011446:Prospective Studies
chemical_list: D015415:Biomarkers; D006709:Homoarginine