A bone density or bone mineral density test detects osteoporosis, a health condition in which your bones become weak and prone to fractures. Osteoporosis is a silent disorder. It means you hardly identify that you have this condition until you break your bone.
Earlier, when the bone density test was not available, your doctor would suspect that you might have this ailment only after an event of bone breakage. However, by the time you reach that stage , your bones get weak, significantly. With the bone density test, your doctor can diagnose osteoporosis accurately while also calculating the risk of fractures.
Bone density test utilizes X-rays to measure the mass (in grams) of calcium and related bone minerals present in a section of your bone. Usually, your doctor (osteologist) will perform this test on your hip bone, spine, or forearm bone.
Why is bone density testing done?
Your osteologist is likely to perform this test for the following reasons –
- To confirm that you have osteoporosis.
- To diagnose the loss in your bone mineral density before a bone fracture.
- To evaluate the risk of bone fractures.
- To monitor and track the treatment procedure.
The mineral content of your bone determines the strength of your bones. The higher the mineral density, the stronger your bones are as a result – lesser risks of fractures.
Bone density tests and bone scans are different. The latter generally needs an injection before the scans. Plus, it detects infections, cancer, fractures, and other anomalies related to bone.
When does your doctor recommend the Bone Density Test?
The chances of developing osteoporosis are higher in women. However, this condition can also affect men. Irrespective of your age and gender, your doctor might prescribe a bone density testing to you in the following scenarios
- If you have lost height – If you see a decrease of at least 4 cm or 1.6 inches in your height, compression fractures in your spine might be the reason. And, those fractures are most likely to be due to osteoporosis.
- If you have got fragility fractures – When a bone gets too fragile, it can break unexpectedly, and the reason can be even a sharp sneeze or cough.
- If you are on medication – Having certain medications, like steroids for a long time, can affect bone-rebuilding and cause osteoporosis.
- You might be at a higher risk of developing osteoporosis if you have undergone an organ transplant or BMT (bone marrow transplant). The reason – anti-rejection drugs used in and after such surgeries can also interrupt the process of bone-rebuilding.
- If you have a hormonal drop – Apart from the menopause-induced natural hormonal dip, women’s estrogen level can also drop due to hysterectomy. In men, some prostate cancer treatments lead to a reduction of testosterone levels. Drop in the levels of sex hormones can also lead to the weakening of bones.
- If the cause(s) is not clear – Although a bone mineral density test can determine lower bone density profiles, it cannot tell you the exact reason(s) behind the condition. To go to the root of this health condition, your doctor will need to do a comprehensive medical examination.
How to prepare for the test?
Bone density testing is quick, non-invasive, and painless. And, you do not need any prior preparations for it.
If you are taking the test at a healthcare facility, inform your doctor if you have had a barium test or CT scan recently. The contrast used in such diagnostic tests is more likely to impact your bone mineral density test.
Medicine and food: Make sure to avoid calcium supplements before the test, at least for 24 hours.
Clothing and accessories: Wear comfortable and loose-fitting clothing and try not to wear outfits with metal zippers and buttons. The lab practitioner will ask you to remove all metallic objects from your pockets, including – change, keys, etc., before the test.
What to expect?
The lab technician will focus on the problem areas where the bones are more susceptible to fractures. It includes the following –
- Lumbar vertebrae (lower portion of the spinal cord)
- Peripheral bones (bones in the forearm, wrist, fingers)
- The femur (the longest bone of the human thigh, extending to the knee from the hip)
If you are taking the bone density test at a medical facility, your doctor will perform it on the central device. You will have to lie on a cushioned platform during the procedure while a mechanical device will move over your body doing the scan. It takes around 10 to 30 minutes to complete the bone density testing procedure. And, it exposes you to a much lower amount of radiation in comparison to chest X-ray.
If you are to take the test for evaluating the peripheral bones, compact and portable machines, the peripheral devices, will be used, which is usually present in drug stores. Peripheral tests are less expensive than the central device tests.
Bone density is likely to differ from one part of your body to the other. Also, the measurement of bone mineral density from your spine is more an accurate indicator of fracture risks than your heel’s measure of bone mineral density. Therefore, to confirm that you have osteoporosis, your doctor will recommend a spine scan using central devices, if your peripheral test comes positive.
What does the result mean?
There are two numbers in which your doctor will report your test results – T-score and Z-score.
T-score is your bone density compared to the expected range in healthy adults of your age and sex. The number of standard deviations (units) shows if your bone density is below or above the standard range. Here is a table for your reference –
|-1 or above
|It means your bone density is normal.
|-1 to -2.5
|It shows that your bone density is below normal, an indication of osteopenia that may lead to osteoporosis.
|-2.5 and below
|It indicates osteoporosis.
The Z-score indicates the number of standard deviations (units) below or above the average for people of your sex, age, weight, or racial origin. In case your Z-score is considerably lower or higher than the expected score, it is more likely to indicate other underlying condition(s) leading to abnormal loss of bone apart from ageing. In such scenarios, your doctor will try to identify the problem and treat it to lower or stop the bone loss.
- How frequently should you take the bone density test?
If you have osteoporosis and are under treatment, your doctor might ask you to go for the test every 1 or 2 years. If you are not suffering from this bone condition, your doctor might also recommend the test to you every 2-years, especially if you are a woman in her menopause state or post-menopause.
- The more calcium and other minerals in your bone, the better. Is it true?
Yes, more calcium and other minerals ensure that your bone density is good and strong bones. The bone density test identifies if or not your bones appear denser through the X-ray. The denser/thicker, the better, because denser bones mean adequate amounts of calcium and minerals are present.