Normal bone density is an important measurement for overall bone health as you age. Spinal bone density can be measured by a variety of methods, but a DEXA/DXA scan has become the gold standard of bone density measurements, as reported by the American Academy of Orthopaedic Surgeons. On a DEXA scan, your bone density is reported as both a T-score and a Z-score. A normal value is a T-score above -1 with an appropriate Z-score near zero.
Significance
Spinal bone density is a measurement of the density of bone in the vertebrae, or spinal bones, in your back. Density of bone in your spine is an informative measurement, as it usually represents the general health of bones throughout your body. Loss of density in your spinal or peripheral bones is known as osteoporosis. Regular screening for bone loss can help to identify osteoporosis before it becomes too severe to reverse.
Types of Tests
The standard test for bone density, according to the American Academy of Orthopaedic Surgeons, is a scan by the dual energy x-ray absorptiometry, or DEXA, method. DEXA scans replaced standard x-rays or other radioactive methods as the primary screening method, though your doctor may order them in specific circumstances. A DEXA scan uses low level x-rays to measure the density of both your spine and hips in a central scan, or of arm and leg bones on a peripheral scan.
Normal Values
After a DEXA scan, you receive two scores pertaining to the density of your spine. The first measurement is called the T-score, and it scores your bone density against the density of a healthy 20-year-old of your gender. As you age, this score will naturally become lower, though it normally stays above -1. The Z-score relates your bone density to the average bone density for your age, gender and race.
Considerations
Loss of bone density is an increasingly recognized medical problem among elderly populations. According to Medline Plus, the DEXA scan results can indicate the severity of bone loss for a patient. If your T-score is less than -1 but greater than -2.5, it indicates osteopenia, the start of bone density loss. If the T-score falls below -2.5, the diagnosis is osteoporosis.
Prevention/Solution
Regular DEXA scans coupled with a healthy lifestyle can minimize spinal bone density loss. As described by the American Academy of Orthopaedic Surgeons reference, patients who have higher risk for bone loss can benefit from regular periodic spinal bone density scans. These patients include those with a history of bone loss or fracture or those on medication that might induce bone loss. Additionally, healthy adults will benefit from scans as well, since bone density loss is a rather non-symptomatic process until fractures occur.
