Vitamin D optimises bone density with bisphosphonates
optimise the effects of bisphosphonates to maintain and improve
bone density in post-menopausal women, says a new study.
Bisphosphonates are well established for post-menopausal osteoporosis treatment and fracture prevention, but questions have arisen to suggest that insufficiency of vitamin D may affect a patient's response.
The new research, published in the BioMed Central journal Musculoskeletal Disorders, looked at the role of blood levels of the vitamin on bone mineral density (BMD) in women taking bisphosphonates and the role of vitamin D/ calcium supplements in women who had stopped taking the medication.
"The data suggest that optimal serum 25 (OH) vitamin D concentration may lead to further reduction in bone loss at the hip in patients on bisphosphonates," wrote lead author Andrew Deane from Kings College London.
Osteoporosis is estimated to affect about 75m people in Europe, the USA and Japan. According to the International Osteoporosis Foundation, the total direct cost of osteoporotic fractures is €31.7bn in Europe, and 17.5bn in the US (2002 figure). The total annual cost of osteoporosis in the UK alone is over £1.7bn (€2.5bn), equivalent to £5m (€7.3m) each day.
The most widely used supplements for the prevention of the disease and to help strengthen bones after diagnosis are calcium, which is a well-known building-block of strong bones, and vitamin D, which has been shown to boost calcium absorption.
"It is still unclear whether addition of calcium/vitamin D supplements leads to an incremental benefit in patients taking bisphosphonates and whether achievement of serum level of 25 (OH) vitamin D of at least 70 nanomoles per litre has an impact on the skeletal response to bisphosphonates," wrote Deane.
"Moreover the maintenance of BMD after bisphosphonates withdrawal with the continuation of calcium/vitamin D supplements only, remains uncertain."
The researchers recruited two patient groups - the first included 112 women receiving bisphosphonates, while the second was comprised of 35 women previously on bisphosphonates for more than five years but use had since been discontinued. The women in the second study continued to take calcium (one gram) and vitamin D (800 IU cholocalciferol) supplements (Calcichew D3 Forte).
Deane and his co-workers report that, in the first study group, serum vitamin D concentrations greater than 70 nanomoles per litre were associated with lower serum parathyroid hormone (PTH) - a measure of calcium metabolism - levels.
PTH levels up to 41 nanograms per litre were linked to significantly higher hip BMD increases following treatment with bisphosphonates, compared to women with PTH levels greater than 41 ng/L.
In the second study group, amongst women who had discontinued the bisphosphonates for 15 months but continued with a daily vitamin D/calcium supplement combo did not show any significant bone loss at the lumbar spine and total hip, said the researchers, although a gradual decline in BMD at the femoral neck was noted.
"Achievement of optimal serum vitamin D concentrations for maximizing bone strength and increases in BMD may be required in patients treated with a bisphosphonate as indicated by our present observation," wrote Deane.
"It may therefore be important for physicians to discuss the additional benefits of vitamin D to such patients."
The researchers called for prospective controlled trials to further investigate the observations from this study.
Source: BMC Musculoskeletal Disorders Volume 8:3, doi:10.1186/1471-2474-8-3 "The impact of vitamin D status on changes in bone mineral density during treatment with bisphosphonates and after discontinuation following long-term use in post-menopausal osteoporosis" Authors: A. Deane, L. Constancio, I. Fogelman and G. Hampson
