BONE MINERAL DENSITOMETRY (BMD)
Bone mineral density (BMD) test is typically used to determine if you have osteoporosis – a disorder characterised by bones that are more fragile and more likely to break.
There are three ways of checking your BMD:
Dual Energy X-ray Absorbitary (DEXA)
Quantitative CT Scan
The most commonly used method is DEXA. It is a simple low radiation test, which is relatively safe, cost effective and produces standardised readings for accurate monitoring over time.
DEXA BMD Test
The test uses low dose X-rays to measure how many grams of calcium and other bone minerals, are packed into a segment of bone. The bones that are most commonly tested are in the spine, hip and sometimes the forearm. The computer processes the energy data emitted from X-Rays, tabulates and calculates the BMD value. Two scores are generated from this scan. One is the T-score, which indicates the amount of bone loss by comparing your BMD at your current age to the peak bone mass achieved by young persons.
The second is the Z-score, measures your bone loss relative to age-matched peers’ expected bone loss. Z-score tells whether your BMD is normal compared to the same age population group. The scan is a painless procedure that lasts between 5 to 15 minutes, depending on the size of the area being scanned and the number of images taken.
Osteoporosis is common in elderly patients and has no symptoms. To detect osteoporosis before your bones begin to fracture, you should have a BMD scan done, especially if you are in the high-risk group for osteoporosis.
Your doctor may prescribe bone mineral density test to:
Determine your risk of bone fracture (broken bones)
Confirm a diagnosis of osteoporosis
Monitor to assess osteoporosis treatment
Monitor changes in bone density before a fracture happens in future.
The higher your bone mineral content, the denser your bones will be. Denser bones are generally stronger and are less likely they are to break.
Although osteoporosis is more common in older women, men also can develop the condition. Regardless of your sex or age, your doctor may recommend a bone density test if you've:
Lost height. People who have lost at least 3 cm in height may have compression fractures in their spines, for which osteoporosis is one of the main causes.
Fractured a bone. Fragility fractures occur when a bone becomes so fragile that it breaks more easily than expected. Fragility fractures can sometimes even be caused by a strong cough or sneeze.
Taken certain drugs. Long-term use of steroid medications, such as prednisone, interferes with the bone-rebuilding process — which can lead to osteoporosis.
Had a drop in hormone levels. In addition to the natural drop in hormones that occurs after menopause, women's estrogen may also drop during certain cancer treatments. Some treatments for prostate cancer reduce testosterone levels in men.