Vitamin D status, estradiol and bone metabolism in elderly female patients with hip fracture

Johannes Karl Maria Fakler

Abstract


Aim: In postmenopausal women increased bone turnover is associated with hip fracture apart from bone mineral density. The aim of this study was to evaluate bone metabolism in consideration of vitamin D and hormonal status in elderly female hip fracture patients compared to controls.

Material and Methods: Circulating 25-hydroxyvitamin D3 (25(OH)D), sex hormones, BTM [osteocalcin (OC); propeptide of type-I collagen (PINP); C-terminal telopeptide of type I collagen (CTX-1); tartrate resistant acid phosphatase 5b, (TRAP5b)] and osteoclastogenic cytokines [soluble receptor activator of nuclear factor kB ligand (sRANKL); osteoprotegerin (OPG)] were measured in patients with a low-energy hip fracture and controls without an incident hip fracture (each group n= 47 females).

Results: 57.4 % of the patients, but only 10.6. % controls had a severe vitamin D deficiency. T-Score at the lumbar spine was comparable in both groups (-1.8 ± 1.5 vs. -1.6 ± 1.4, p=0.535). In hip fracture patients 25(OH)D (p<0.001), albumin (p<0.001), osteocalcin (OC) (p<0.001) and sRANKL (p<0.001) levels were lower compared to controls, whereas estradiol (p<0.001), cortisol (p<0.001), CTX-1 (p<0.001) and OPG (p<0.001) were higher. Linear regression analysis revealed an independent association between 25(OH)D and CTX-1 in female fracture patients (p=0.023). Higher estradiol levels after hip fracture correlated inversely with OC (p=0.018) and TRAP5b (p=0.004).

Multivariable regression analysis demonstrated that 25(OH)D, OC, estradiol (each p<0.001) and albumin (p=0.002) were independently associated with fracture. Higher estradiol levels correlated inversely with OC in fracture patients (p=0.018).

Conclusion: 25(OH)D was an independent risk factor of hip fracture and demonstrated an independent association with CTX-1. Unchanged or lower levels of bone formation markers were not associated with 25(OH)D and were partly related to higher of levels estradiol presumably induced by trauma.


Keywords


Hip fracture, vitamin D, bone metabolism, bone turnover, bone turnover markers, OPG, sRANKL, estradiol

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