Glucocorticoid-induced osteoporosis:

Bone biopsy and densitometry findings in a child with Camurati-Engelmann disease

Progressive diaphyseal dysplasia (MIM 131300), also known as Camurati-Engelmann disease (CED), is a rare autosomal dominant craniotubular dysplasia caused by mutations in the transforming growth factor beta1 (TGF-beta1) gene. Radiographs of the long bones of a 9-year-old boy presenting with waddling gait, muscular weakness, underweight, and severe skeletal pain showed symmetric diaphyseal cortical thickening pathognomonic for CED. The diagnosis was verified by detecting a mutation in exon 4 of the TGF-beta1 gene. Full body bone mineral densitometry studies performed before treatment with prednisolone were indicative for osteoporosis (Z-scores for the lumbar spine and femoral neck -2.3 and -3.2, respectively). A transiliac bone biopsy showed markedly reduced trabecular bone volume. Oral prednisolone was initiated, and subsequently, pamidronate infusions were commenced in an attempt to prevent progression of osteoporosis. To our knowledge, this is the first time bone biopsy and bone mineral densitometry studies have been performed and bisphosphonate treatment evaluated in a child with CED.

Bone health in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED): findings in 25 adults

OBJECTIVE

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is characterized by chronic mucocutaneous candidiasis and autoimmune destruction of endocrine organs. The resulting endocrinopathies and their treatment may impact bone health. The purpose of our study was to assess bone health and its correlates in adult patients with APECED.

PATIENTS AND METHODS

Twenty-five adults (12 males) with APECED were prospectively assessed. Data on their previous medical history were collected from hospital records. Areal bone mineral density (aBMD) for the lumbar spine (L1-L4), femoral neck and whole body as well as volumetric BMD (vBMD) for the lumbar spine (L2-L4) were measured with dual-energy X-ray absorptiometry (DXA).

RESULTS

Mean age was 34 years (range 21-59 years). All patients had 1-4 autoimmune endocrinopathies, the most common being adrenocortical failure (20 patients) and hypoparathyroidism (18 patients). Osteopaenia or osteoporosis was present in 28%. The median (range) aBMD Z-scores were for the lumbar spine -0.3 (-2.3 to +3.3) and for the femoral neck, -0.1 (-2.2 to +2.0). The BMD Z-scores tended to be higher in patients with hypoparathyroidism than in patients with normal parathyroid function (at the lumbar spine +0.4 vs.-1.2, P = 0.016, and at the femoral neck +0.3 vs.-0.4, P = 0.090). Adrenocortical failure had a negative impact on BMD. Six patients had had low-impact fractures and three were diagnosed with compression fractures.

CONCLUSIONS

Despite the complex endocrine problems, the overall prevalence of symptomatic osteoporosis is low in adults treated for APECED. Osteopaenia is frequently observed and warrants follow-up. Treated hypoparathyroidism may have a positive, and adrenocortical failure a negative, impact on bone health.

Recommendations for the Registration of Agents to be Used in the Prevention and Treatment of Glucocorticoid-Induced Osteoporosis: Updated Recommendations from the Group for the Respect of Ethics and Excellence in Science

OBJECTIVES

The Group for the Respect and Excellence in Science (GREES) has reviewed and updated their recommendations for clinical trials to evaluate the efficacy and safety of new chemical entities to be used in the treatment and prevention of glucocorticoid-induced osteoporosis (GIOP).

METHODS

Consensus discussion of the committee.

RESULTS

With the exception of steroid use posttransplantation, there is no need to differentiate between underlying diseases. Prevention and treatment for GIOP are dependent on exposure to glucocorticoids rather than T-scores as in postmenopausal osteoporosis (PMO). If fracture data are obtained for PMO, it need not be repeated for GIOP, relying instead on bone mineral density (BMD) trials of at least 1 year. GREES recommends several changes in the previous guidance for GIOP. The committee saw no need to repeat preclinical studies if those have been previously done to assure bone quality in PMO. Similarly, phase I and phase II trials, if careful dose selection has been done for PMO, should not be repeated. The "prevention" and "treatment" claims should remain. Since the most recent evidence suggests significant increase in fracture risk for daily doses of prednisone of 5 mg/day or equivalent, clinical trials should concentrate on patients receiving at least this daily dosage. The emergence of bisphosphonates as the reference treatment, together with the rapid bone loss and high fracture incidence in glucocorticoid users, necessitates recommending a noninferiority trial design with lumbar spine BMD as the primary endpoint after 1 year.

CONCLUSIONS

Registration of new chemical entities to be used in the management of GIOP should be granted, based on a 1-year noninferiority trial, using BMD as primary outcome and alendronate or risedronate as comparator. Demonstration of antifracture efficacy should have been previously demonstrated in PMO.

Osteoporosis in chronically ill children

Gains in bone mass are very rapid during adolescence and peak bone mass, the most important determinant of osteoporosis, is attained by early adulthood. Glucocorticoids, widely used in children with chronic illness, are known to impact bone mass and quality. In addition, disease and treatment-related factors, nutrient and hormone deficiencies and decreased physical activity may all negatively affect bone mass accrual. Although decreased bone density is increasingly recognized in chronically ill children, current knowledge of the epidemiology, diagnosis and optimal treatment of pediatric secondary osteoporosis is limited. In addition to bone densitometry, biochemical and radiographic tests should be used in the diagnosis of osteoporosis. Bone histomorphometry may be needed in selected situations. At risk children should be advised to ensure sufficient calcium and vitamin D intake and weight bearing physical activity. Growth and pubertal development require careful assessment because of their close correlation with bone formation. Given limited experience with bisphosphonates, it seems prudent to target antiresorptive therapy to those children who have developed symptomatic disease. Ideally this should be done in controlled settings. Early identification and adequate intervention, in selected cases with bisphosphonates, is needed in order to prevent deleterious skeletal complications of osteoporosis in chronically ill children.

Effects of cortisol and bone morphogenetic protein-2 on stromal cell differentiation: correlation with CCAAT-enhancer binding protein expression

Bone marrow stroma contain pluripotential cells with the potential to differentiate into various mesenchymal cell lineages. We compared the effect of cortisol and bone morphogenetic protein-2 (BMP-2) on the differentiation of murine ST-2 stromal cells into mature osteoblasts or adipocytes. ST-2 cells were cultured for 3-27 days in the presence of 10% fetal bovine serum, 100 microg/mL ascorbic acid, and 5 mmol/L beta-glycerolphosphate in the presence or absence of cortisol at 1 micromol/L or BMP-2 at 1 nmol/L. Untreated ST-2 cells expressed high levels of alkaline phosphatase activity (APA) 15 days after confluence, and this was followed by the appearance of mineralized nodules after 24 days. BMP-2 accelerated and intensified the appearance of cells expressing APA and the presence of mineralized nodules. In contrast, cortisol decreased APA, prevented the formation of mineralized nodules, and induced a cellular phenotype characteristic of adipocytes. Untreated stromal cells expressed osteocalcin, Cbfa1, type I collagen, and alkaline phosphatase mRNA. BMP-2 increased osteocalcin and alkaline phosphatase mRNA, whereas cortisol suppressed their expression, as well as Cbfa1 and type I collagen transcripts. Cortisol enhanced, and BMP-2 downregulated, peroxisome proliferator-activated receptor gamma 2 and adipsin transcripts. The C/EBP transcription factors regulate genes critical for adipocytic and osteoblastic differentiation. Cortisol increased the expression of C/EBP alpha, beta, delta, and gamma mRNA levels, whereas BMP-2 had minor effects on C/EBP expression. In conclusion, BMP-2 accelerates the differentiation of stromal cells toward an osteoblastic phenotype, whereas glucocorticoids induce their differentiation toward an adipocytic phenotype.

Recommendations for the prevention and treatment of glucocorticoid-induced osteoporosis: 2001 update. American College of Rheumatology Ad Hoc Committee on Glucocorticoid-Induced Osteoporosis

Glucocorticoid-induced bone loss should be prevented, and if present, should be treated (Table 2). Supplementation with calcium and vitamin D at a dosage of 800 IU/day, or an activated form of vitamin D (e.g., alfacalcidiol at 1 microg/day or calcitriol at 0.5 microg/day), should be offered to all patients receiving glucocorticoids, to restore normal calcium balance. This combination has been shown to maintain bone mass in patients receiving long-term low-to-medium-dose glucocorticoid therapy who have normal levels of gonadal hormones. However, while supplementation with calcium and vitamin D alone generally will not prevent bone loss in patients in whom medium-to-high-dose glucocorticoid therapy is being initiated, supplementation with calcium and an activated form of vitamin D will prevent bone loss. There are no data available to support any conclusion about the antifracture efficacy of the combination of calcium supplementation plus an activated form of vitamin D. Antiresorptive agents are effective in the treatment of glucocorticoid-induced bone loss. All of these agents either prevent bone loss or modestly increase lumbar spine bone mass and maintain hip bone mass. While there are no randomized controlled trials of prevention of glucocorticoid-induced bone loss or radiographic vertebral fracture outcomes with HRT or testosterone, patients receiving long-term glucocorticoid therapy who are hypogonadal should be offered HRT. The bisphosphonates are effective for both the prevention and the treatment of glucocorticoid-induced bone loss. Large studies have demonstrated that bisphosphonates also reduce the incidence of radiographic vertebral fractures in postmenopausal women with glucocorticoid-induced osteoporosis. Treatment with a bisphosphonate is recommended to prevent bone loss in all men and postmenopausal women in whom long-term glucocorticoid treatment at > or =5 mg/day is being initiated, as well as in men and postmenopausal women receiving long-term glucocorticoids in whom the BMD T-score at either the lumbar spine or the hip is below normal. While there is little information on the prevention or treatment of bone loss in premenopausal women, these women, too, may lose bone mass if they are being treated with glucocorticoids, so prevention of bone loss with antiresorptive agents should be considered. If bisphosphonate therapy is being considered for a premenopausal woman, she must be counseled regarding use of appropriate contraception. The therapies to prevent or treat glucocorticoid-induced bone loss should be continued as long as the patient is receiving glucocorticoids. Data from large studies of anabolic agents (e.g., PTH) and further studies of combination therapy in patients receiving glucocorticoids are eagerly awaited so additional options will be available for the prevention of this serious complication of glucocorticoid treatment.