Osteocalcin has been demonstrated to be diminished in HIV positive individuals, a phenomenon which is also known to occur in the presence of other viral infectious agents as well as long-standing hepatic pathology. Fasting urinary calcium lacks the specificity and sensitivity necessary to serve as an indicator of bone turnover. Moreover, urinary markers of bone resorption demonstrate significant circadian patterns. Therefore, it is best to obtain a 24-hour urine collection, normalized to creatinine excretion, to measure urinary calcium. These are collagen degradation products that are released from bone matrix into the circulation upon its breakdown by osteoclastic activity and can be used as a marker of bone resorption.
Deoxypyridinoline assay has the advantage of demonstrating a high degree of specificity.
It has long been understood that a sedentary lifestyle is a major factor in the development of osteoporosis. This may be a choice on the part of the patient, but may also result from weakness or fatigue or the occurrence of neuropathy secondary to HIV infection or antiretroviral therapy. In both men and women, resistance exercise at relatively high weight loads has been demonstrated to increase bone mineral density. Caffeine plays a minor role in bone loss and appears to be related to dose and the absence of adequate concomitant calcium intake. Chronic alcoholism has been demonstrated to result in decreased bone mass.