HIV-infected individuals have a lower bone density than uninfected individuals (Loiseau-Peres 2002). Bone density is determined by the measurement of X-ray absorption (e.g. DEXA scan). Results are given as the number of standard deviations (the T-score) from the mean value in young, healthy individuals. Values between -1 and -2.5 standard deviations (SD) are referred to as osteopenia, values above -2.5 SD as osteoporosis.
In addition to HIV infection, other factors such as malnutrition, diminished fat tissues, steroid treatment, hypogonadism, immobilization and treatment with PIs and NRTIs, seem to play a role in the pathogenesis of this disorder. Osteopenia and osteoporosis are often asymptomatic. Osteoporosis occurs mainly in the vertebrae, lower arms and hips.
The following tests should be performed on all patients with AIDS: a lumbar spine X-ray in the standard anteroposterior and lateral views, bone density measurement (DEXA scan) of the lumbar spine and hip; and laboratory blood tests, including calcium, phosphate and alkaline phosphatase. Osteopenia should be treated with 1000 I.E. vitamin D daily and a calcium-rich diet or calcium tablets with a dose of 1200 mg/day. Patients should be advised to exercise and give up alcohol and nicotine. In cases with osteoporosis, bisphosphonates (e.g. alendronat 70 mg once a week) should be added. The tablets should be taken on an empty stomach 30 min before breakfast, and an upright position should be maintained for at least 30 min. No calcium should be taken on this day. Antiretroviral therapy should not be taken together with calcium. Because testosterone suppresses osteoclasts, hypogonadism should be treated. Alcohol and smoking should be avoided; regular exercise is an essential part of the therapy.
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