Clinical calcium
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A number of clinical risk factors that provide information on fracture risk over and above that given by BMD have been defined. WHO proposed FRAX (fracture risk assessment tool) in which the fracture probability could be calculated by the use of risk factors with or without BMD. The proposed independent risk factors are age, a prior fragility fracture, a parental history of hip fracture, smoking, use of systemic corticosteroids, excess alcohol intake, secondary osteoporosis, and rheumatoid arthritis. Management algorithms in postmenopausal women based on an health analysis have been proposed in several countries including UK, Sweden, Germany, USA and Canada.
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In 2006, a set of guidelines was released in Japan regarding the initiation of medical treatment to prevent fragility fracture with risk factors considered. In February this year, a WHO working group announced the development of the Fracture Risk Assessment Tool (FRAX), which estimates fracture risk based on age, sex, bone density at the femoral neck (body mass index if bone density is not available), previous fragility fracture in adulthood, parental fracture history at the femoral neck, current smoking, steroid use, secondary osteoporosis/rheumatoid arthritis, and alcohol consumption. And then, the NOF released guidelines incorporating FRAX in the US. WHO recommends that the threshold of medical treatment should be set based on each country's medical circumstances and healthcare economic situation.
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Most patients with inherited hypophosphatemic Rickets/Osteomalacia have mutations in the PHEX gene. In this brief review, we focus on the treatment for patients with this mutation. First, molecular basis of inherited hypophosphatemic Rickets/Osteomalacia, followed by pathophysiology of PHEX and its related disorders is described. ⋯ The most common treatment for this disorder is administration of phosphate and vitamin D, both internationally and in Japan. Degree of the increment in serum inorganic phosphorus levels one hour after phosphate administration, in addition to a decrease in alkaline phosphatase levels is valuable in the monitoring of the treatment. During childhood, markers in a longer term, namely, improvement of X-ray findings and that of height velocity are also useful.
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Pseudohypoparathyroidism type I b is characterized by unresponsiveness solely to parathyroid hormone in contrast to pseudohypoparathyroidism type I a which induces resistance to several hormones. Abnormal imprinting of GNAS gene which encodes Gsalpha protein is considered to be responsible for pseudohypoparathyroidism type Ib. ⋯ However, the detailed mechanism how these deletions cause abnormal imprinting of GNAS gene remains to be elucidated. Analysis of pathogenesis of pseudohypoparathyroidism type Ib should contribute to the understanding of regulatory mechanisms of gene expression.
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Pseudophypoparathyroidism (PHP) is characterized by hypocalcemia, hyperphosphatemia and elevated levels of parathyroid hormone (PTH) due to resistance to PTH. PHP type I a is caused by heterozygous inactivating mutation of the GNAS1 gene, which encodes signal transducer, Gsalpha. PHP type I a is associated with Albright's osteodystrophy (AHO). Those patients who have AHO phenotype without hormone resistance are affected by pseudopseudohypoparathyroidism.