Metabolic Bone Diseases Other than Osteoporosis

Abstract

Osteogenesis imperfecta is a hereditary disorder of the connective tissue caused by qualitative or quantitative abnormalities involving type I collagen, with varied phenotypic presentations. The diagnosis should be considered in any child with recurrent fractures from minimal trauma and the focus of treatment should be multidisciplinary in order to oversee early care and minimize complications. Osteomalacia is often neglected especially in its early stages because of the nonspecific nature of symptoms such as vague bone pain and muscle weakness. Symptoms include chronic bone and muscle pain, weakness, fatigue, difficulty in walking, and a high risk of fractures due to bone fragility. The most characteristic laboratory findings are a lower serum calcium level, a decrease in urinary calcium levels, hypophosphatemia, and increased levels of alkaline phosphatase. Vitamin D is effective in the treatment of nutritional osteomalacia, or for malabsorption. Tumor-induced osteomalacia is treated with a phosphate supplement, along with vitamin D, until the tumor has been identified and excised. Paget’s disease of bone is a chronic skeletal disease characterized by increased osteoclastic activity that leads to increased bone reabsorption. It is usually asymptomatic and discovered incidentally. The main clinical manifestations are bone pain, fractures, skeletal deformities, and secondary arthritis. The diagnosis can be made when high serum alkaline phosphatase activity is found, or by routine X-ray examination. The objective of treatment is to relieve pain, restore normal bone metabolism, decrease bone vascularization, and prevent future complications.