title: Does serum osteoprotegerin level relate to fragility fracture in elderly women with low vitamin D status?
abstract: BACKGROUND
  Increased osteoprotegerin (OPG) with elevated bone turnover is supposed to be a homeostatic mechanism limiting bone loss.
  
  
  METHODS
  Whether osteoprotegerin relates to low-energy fracture in elderly women was investigated by analyzing the relationship between OPG and bone turnover. Sixty-nine women with a first fragility hip fracture participated. The reference group consisted of 23 age-matched women. Serum calcium, 25-OHD3, parathormone, osteocalcin (OC), cross-linked C-terminal telopeptides (CTX-I), tartrate-resistant acid phosphatase (TRAP5b), and osteoprotegerin were assayed immediately post-fracture.
  
  
  RESULTS
  In both groups, median vitamin D and calcium concentrations were in the low reference range, CTX-I were moderately elevated, and TRAP5b activity and parathormone were within the reference range. Significantly lower osteocalcin, a trend to higher OPG, and an inverse correlation between OPG and osteocalcin was found in the fracture group. The distribution of fracture was related to osteocalcin and OPG concentrations: the lower the OC level, the higher the number of women with fracture at increasing OPG concentrations. A relative imbalance between bone formation and resorption was found in the fracture group. The lowest osteocalcin level (Q1) was observed only and vitamin 25-OHD3 insufficiency predominantly in the fracture group and higher OPG, TRAP5b, and elevated CTX-I concentrations (Q3) were found more often or predominantly in this group.
  
  
  CONCLUSIONS
  The data demonstrate a relative imbalance between bone formation and resorption associated with fragility fracture in elderly women with low vitamin D status. The authors suggest that compensatory elevation of serum OPG, particularly with reduced bone formation, is insufficient to limit bone loss leading to fracture.
authors.affiliation: Department of Laboratory Medicine, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland. odes@cm.umk.pl
authors.forename: Grazyna
authors.initials: G
authors.lastname: Sypniewska
authors.forename: Izabela
authors.initials: I
authors.lastname: Sobanska
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Pater
authors.forename: Kornelia
authors.initials: K
authors.lastname: Kedziora-Kornatowska
authors.forename: Wieslaw
authors.initials: W
authors.lastname: Nowacki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D050723:Fractures, Bone / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D053244:Osteoprotegerin / Q000097:blood*; D014807:Vitamin D / Q000097:blood*
chemical_list: D053244:Osteoprotegerin; D015675:Osteocalcin; D014807:Vitamin D