Does serum osteoprotegerin level relate to fragility fracture in elderly women with low vitamin D status?
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.
Sypniewska
Grazyna
G
Department of Laboratory Medicine, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland. odes@cm.umk.pl
Sobanska
Izabela
I
Pater
Agnieszka
A
Kedziora-Kornatowska
Kornelia
K
Nowacki
Wieslaw
W
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*
D053244:Osteoprotegerin; D015675:Osteocalcin; D014807:Vitamin D