Utility of DXA for monitoring, technical aspects of DXA BMD measurement and precision testing.

Monitoring a patient's bone mineral density (BMD) is one of the main reasons for dual-energy X-ray absorptiometry (DXA) referral. It is widely recommended by clinical guidelines, and the accepted standard in practice for managing patients with osteoporosis and other disorders. Clinicians and DXA providers must be familiar with the scientific rationale and procedures involved in measurement science to obtain accurate and reproducible results.

Dual-energy X-ray absorptiometry diagnostic discordance between Z-scores and T-scores in young adults.

Diagnostic criteria for postmenopausal osteoporosis using central dual-energy X-ray absorptiometry (DXA) T-scores have been widely accepted. The validity of these criteria for other populations, including premenopausal women and young men, has not been established. The International Society for Clinical Densitometry (ISCD) recommends using DXA Z-scores, not T-scores, for diagnosis in premenopausal women and men aged 20-49 yr, though studies supporting this position have not been published.

DXA-generated Z-scores and T-scores may differ substantially and significantly in young adults.

Central dual-energy X-ray absorptiometry (DXA) is the gold standard for non-invasive measurement of bone mineral density (BMD). Using this value and subject demographics, DXA software calculates T-scores and Z-scores. Professional society guidelines for the management of osteoporosis are based on T-scores and Z-scores, rather than on the actual BMD value.

Strategies for the prevention and treatment of osteoporosis during early postmenopause.

During the perimenopause, both the quantity and quality of bone decline rapidly, resulting in a dramatic increase in the risk of fracture in postmenopausal women. Although many factors are known to be associated with osteoporotic fractures, measures to identify and treat women at risk are underused in clinical practice. Consequently, osteoporosis is frequently not detected until a fracture occurs.

Bone density changes with once weekly risedronate in postmenopausal women.

Risedronate 5 mg daily is approved by the Food and Drug Administration to treat postmenopausal osteoporosis. Gastrointestinal (GI) symptoms are common with daily bisphosphonates, but recent studies show that once weekly treatment may be better tolerated. Risedronate 30 mg is approved to treat Paget s disease of bone.

A syndrome of hypocalciuric hypercalcemia caused by autoantibodies directed at the calcium-sensing receptor.

Antibodies to cell surface receptors can cause endocrine dysfunction by mimicking or blocking the actions of their respective hormones. We sought patients with autoantibodies to the extracellular calcium (Ca(2+)(o))-sensing receptor (CaR), which sets the normal level of blood calcium, that mimic the genetic disorder, familial hypocalciuric hypercalcemia, caused by heterozygous inactivating mutations of the CaR. Four individuals from two kindreds were identified with PTH-dependent hypercalcemia, who had other autoimmune manifestations: one with sprue and antigliadin and antiendomyseal antibodies and three with antithyroid antibodies.