Protective effect on vitamin D2 on bone apposition from the inhibitory action of hydrocortisone in rats

Prevention and treatment of glucocorticoid-induced osteoporosis with active vitamin D3 analogues: a review with meta-analysis of randomized controlled trials including organ transplantation studies

The aim of this review with meta-analysis was to determine if there is a rationale to use activated forms of vitamin D3 to treat or prevent glucocorticoid-induced osteoporosis, and to compare the effect of active vitamin D3 metabolites with that of other anti-osteoporosis therapies. We performed a systemic search using MEDLINE/PubMed (1966-2003). Animal studies and clinical trials involving humans with data on therapy to treat or prevent glucocorticoid-induced osteoporosis with active vitamin D3 analogues were included. Animal studies and basic research studies with active vitamin D3 were reviewed (qualitative review). Meta-analysis (quantitative review) on clinical trials (including organ transplantation studies) was performed with percent change in lumbar spine bone mineral density or bone mineral content as the primary outcome measure; the secondary outcome measure was incidence of vertebral fractures. Fifty-four articles were found. Animal and basic research studies showed that active vitamin D3 analogues can inhibit bone loss during treatment with glucocorticoids. Concerning the effect on bone mineral density, the pooled effect size of active vitamin D3 analogues compared with no treatment, placebo, plain vitamin D3 and/or calcium was 0.35 (95% confidence interval (CI) 0.18, 0.52). Compared with bisphosphonates, the pooled effect size was -1.03 (95% CI -1.71, -0.36). The pooled estimate of the relative risk for vertebral fractures of active vitamin D3 analogues compared with no treatment, placebo, plain vitamin D3 and/or calcium was 0.56 (95% CI 0.34, 0.92) and compared with bisphosphonates it was 1.20 (95% CI 0.32, 4.55). Active vitamin D3 analogues not only preserve bone during glucocorticoid therapy more effectively than no treatment, placebo, plain vitamin D3 and/or calcium, but are also more effective in decreasing the risk of vertebral fractures. Bisphosphonates, however, are more effective in preserving bone and decreasing the risk of vertebral fractures than active vitamin D3 analogues.

Corticosteroid osteoporosis

Glucocorticoids produce osteoporosis via a number of mechanisms, the most important of which is probably inhibition of bone formation. This results in reduction in bone mass of 10-20% at commonly assessed sites, but the bone loss is 30-40% when predominantly trabecular bone is measured. The dosage and duration of steroid treatment influence the extent of bone loss, but other factors are not predictive. At the present time, a patient who has demonstrable sex hormone deficiency should receive appropriate replacement therapy. Optimization of calcium intake is advisable. If bone loss is severe or continues in spite of these measures, the addition of a bisphosphonate, calcitonin, fluoride or a vitamin D metabolite may be appropriate, according to local availability. Thiazide diuretics can be combined with all of these regimens. If combined with vitamin D or its metabolites, careful monitoring of serum calcium levels should be undertaken. Bone density should be monitored annually until such time as it is stable.

Interleukin-6 is produced by bone and modulated by parathyroid hormone

Interleukin-6 (IL-6) is a cellular regulatory molecule, the diverse functions of which relate to cells both within and outside the immune system. In this report we demonstrated that bone tissue, specifically osteoblasts, produce interleukin-6 and that this function can be modulated by the osteotrophic hormone parathyroid hormone (PTH). Given that the complex process of bone remodeling is now thought to be regulated not only by systemic hormones but also by locally produced factors, the existence of a parathyroid hormone-stimulated production of interleukin-6 by osteoblasts may have important physiological significance.

Trabecular bone morphometry in beagles with hyperadrenocorticism and adrenal adenomas

Trabecular bone morphometry was done on rib samples of beagles with hyperadrenocorticism and adrenal adenomas to evaluate bone loss and the remodeling changes responsible. Beagles diagnosed as having clinical hyperadrenocorticism and those with milder or subclinical hyperadrenocorticism diagnosed on the basis of adrenal and pituitary lesions at necropsy had increased adrenal and pituitary gland weights. In a group of dogs with adrenal cortical adenomas there was atrophy of remaining cortex, and the combined weight of adrenal glands or pituitary weights were not increased. In dogs with clinical hyperadrenocorticism, mean trabecular bone volume was 25% less than controls (P = 0.10). In both clinical and subclinical hyperadrenocorticism groups, the extent of trabecular surface with unmineralized osteoid matrix and osteoblasts was significantly reduced. There were no changes in resorption surfaces or number of osteoclasts present. No bone changes were seen in dogs with adrenal adenomas. In dogs with hyperadrenocorticism it appeared that decreased bone formation was primarily responsible for the relative osteopenia that developed. Although parathyroid glands were moderately enlarged in those dogs for which weights were available, the bone changes were not those of increased remodeling expected in hyperparathyroidism.