Osteoporosis and osteopenia

Osteoporosis is a condition where the bones lose mass and density. It is commonly referred to as 'thinning of the bones' and occurs most commonly in older, post-menopausal women. If enough bone density is lost, the risk of fracture increases. When bone mineral density (BMD) has fallen so low that an individual has a fracture risk four to five times higher than the average for the population, the condition is defined as osteoporosis.

Osteopenia refers to less severe bone mineral loss. Neither condition is an AIDS-defining condition.

Reduced bone mass can be diagnosed using a dual-energy X-ray absorptiometry (DEXA) scan, an X-ray based method which measures the density of different body compartments such as fat and bone. It is usually conducted on the bones of the spine and hip.