Increased Bone Density

Abstract: Osteopetrosis ("marble bone disease") is a descriptive term that refers to a group of rare, heritable disorders of the skeleton characterized by increased bone density on radiographs. The overall incidence of these conditions is difficult to estimate but autosomal recessive osteopetrosis (ARO) has an incidence of 1 in 250,000 births, and autosomal dominant osteopetrosis (ADO) has an incidence of 1 in 20,000 births. Osteopetrotic conditions vary greatly in their presentation and severity, ranging from neonatal onset with life-threatening complications such as bone marrow failure (e.g. classic or "malignant" ARO), to the incidental finding of osteopetrosis on radiographs (e.g. osteopoikilosis). Classic ARO is characterised by fractures, short stature, compressive neuropathies, hypocalcaemia with attendant tetanic seizures, and life-threatening pancytopaenia. The presence of primary neurodegeneration, mental retardation, skin and immune system involvement, or renal tubular acidosis may point to rarer osteopetrosis variants, whereas onset of primarily skeletal manifestations such as fractures and osteomyelitis in late childhood or adolescence is typical of ADO. Osteopetrosis is caused by failure of osteoclast development or function and mutations in at least 10 genes have been identified as causative in humans, accounting for 70% of all cases. These conditions can be inherited as autosomal recessive, dominant or X-linked traits with the most severe forms being autosomal recessive. Diagnosis is largely based on clinical and radiographic evaluation, confirmed by gene testing where applicable, and paves the way to understanding natural history, specific treatment where available, counselling regarding recurrence risks, and prenatal diagnosis in severe forms. Treatment of osteopetrotic conditions is largely symptomatic, although haematopoietic stem cell transplantation is employed for the most severe forms associated with bone marrow failure and currently offers the best chance of longer-term survival in this group. The severe infantile forms of osteopetrosis are associated with diminished life expectancy, with most untreated children dying in the first decade as a complication of bone marrow suppression. Life expectancy in the adult onset forms is normal. It is anticipated that further understanding of the molecular pathogenesis of these conditions will reveal new targets for pharmacotherapy.

Abstract: Over 90% of women with anorexia nervosa demonstrate osteopenia, and almost 40% demonstrate osteoporosis at one or more skeletal sites. In addition to estrogen deficiency causing an increase in bone resorption, nutritional effects on the GH-IGI-I axis may contribute to the severe bone loss in this population by decreasing bone formation. We tested the hypothesis that recombinant human IGF-I (rhIGF-I) would increase bone density in women with anorexia nervosa and furthermore assessed the effects of combined rhIGF-I and oral contraceptive administration (OCP) in this population. Sixty osteopenic women with Diagnosis and Statistical Manual of Mental Disorders IV Revised confirmed anorexia nervosa [age (25.2 +/- 0.7 yr, range 18-38 yr), body mass index (17.8 +/- 0.3 kg/m(2) ), spinal bone mineral density T score (-2.1 +/- 0.1 SD) were randomized to one of four treatment groups [rhIGF-I (30 microg/kg sc twice daily) and a daily oral contraceptive (Ovcon 35, 35 microg ethinyl estradiol and 0.4 mg norethindrone], rhIGF-I alone (30 microg/kg sc twice daily), oral contraceptive alone, or neither treatment for 9 months. All subjects received calcium 1500 mg/d and a standard multivitamin containing 400 IU of vitamin D. Administration of rhIGF-I was placebo controlled and blinded to subjects. The rhIGF-I was titrated to maintain IGF-I levels within the age-adjusted normal range for each patient and was well tolerated. The effects of rhIGF-I and OCP were analyzed simultaneously among all subjects in a factorial analysis and in an analysis of the four individual treatment groups. Anteroposterior spinal bone density increased significantly in response to rhIGF-I (1.1% +/- 0.5% vs. -0.6% +/- 0.8%, P = 0.05, all rhIGF-I vs. all placebo treated, respectively, by analysis of covariance). In contrast, OCP did not result in increased bone density (0.8% +/- 0.6% vs. -0.4% +/- 0.8%, P = 0.21, all OCP vs. all non-OCP treated, respectively, by analysis of covariance). However, bone density increased to the greatest extent in the combined treatment group (rhIGF-I and OCP), compared with control patients receiving no active therapy (1.8% +/- 0.8% vs. 0.3% +/- 0.6% vs. -0.2% +/- 0.8% vs. -1.0% +/- 1.3%, rhIGF-I and OCP vs. rhIGF-I alone vs. OCP alone vs. no active therapy, P < 0.05 for rhIGF-I and OCP vs. no active therapy). These data demonstrate that osteopenic women with anorexia nervosa treated with rhIGF-I showed more beneficial changes in bone density, compared with patients not treated with rhIGF-I. Antiresorptive therapy with OCP is not sufficient to improve bone density in undernourished patients, but such therapy may augment the effects of rhIGF-I in a combined treatment strategy. Further long-term studies are needed to investigate the effects of rhIGF-I and combined anabolic/antiresorptive strategies on bone in women with anorexia nervosa.

Abstract: Radiation therapy has important applications in curative, adjuvant, and palliative therapy for a wide range of malignant conditions. Evidence of radiation therapy may be seen on radiologic images obtained subsequent to therapy. Bone growth disturbances may be observed in the immature axial or appendicular skeleton. Complications in the mature skeleton include osteoradionecrosis, pathologic fracture, and radiation-induced neoplasms. Radiologic features of mandibular osteoradionecrosis include ill-defined cortical destruction without sequestration. In osteoradionecrosis of the ribs, clavicle, scapula, and humerus, radiography may demonstrate osteopenia, disorganization and coarsening of trabecular architecture, and cortical irregularity; computed tomography more clearly depicts subtle fractures, alterations in bone architecture, and dystrophic soft-tissue calcification. In osteoradionecrosis of the spine, hematopoietic cellular elements of the spinal marrow are replaced with fat, which has high signal intensity on T1-weighted magnetic resonance images and intermediate signal intensity on T2-weighted images. Radiation-induced changes in the pelvis include osteopenia, increased bone density, and widening and irregularity of the sacroiliac joints. Radiation-induced osteochondromas are radiographically identical to those that arise spontaneously. Radiographic findings in radiation-induced sarcoma demonstrate an aggressive pattern of bone destruction. Awareness of the varied radiographic manifestations of radiation-induced changes in bone and correlation with clinical features and the radiation field will usually allow distinction of these changes from those associated with other pathologic conditions.