How osteoporosis is diagnosed
Osteoporosis is diagnosed with a bone density test called a DEXA scan (dual-energy X-ray absorptiometry). This is a quick, painless X-ray that measures how much mineral is in your bones. You lie on a table for 10 to 30 minutes while the machine scans your hip, spine, and sometimes your forearm. The scan itself takes no longer than a regular X-ray and uses very little radiation — less than you get from a day in the sun.
Your doctor will order a DEXA scan if you have risk factors for bone loss: you are a woman over 65, a man over 70, you have had a fracture from a minor fall, you take steroids long-term, or you have a condition that affects bone health like rheumatoid arthritis or kidney disease. Some doctors also recommend screening for women between 50 and 65 if they have other risk factors.
The scan produces a score called a T-score, which compares your bone density to that of a healthy 30-year-old. This single number tells your doctor whether your bones are normal, thinning, or have osteoporosis. The results come back within a few days, and your doctor will explain what they mean at your next visit or by phone.
Key Takeaways
- A DEXA scan is the only way to diagnose osteoporosis; no blood test or symptom alone can confirm it.
- Your T-score compares your bone density to a healthy young adult's, and the number determines whether you have normal bones, osteopenia, or osteoporosis.
- A T-score of -1.0 or higher is normal, between -1.0 and -2.5 is osteopenia (bone thinning), and -2.5 or lower is osteoporosis.
- Most insurance covers DEXA screening for women 65 and older and men 70 and older without cost to you.
Understanding your T-score results
The T-score is a number between -4 and +3, and the minus sign matters. A higher number (closer to zero or positive) means stronger bones. A lower number (more negative) means weaker bones.
Here is what the ranges mean:
| T-Score Range | What It Means |
|---|---|
| -1.0 or higher | Normal bone density |
| -1.0 to -2.5 | Osteopenia (low bone mass, but not yet osteoporosis) |
| -2.5 or lower | Osteoporosis |
If you have osteopenia, your bones are weaker than normal but you do not yet have osteoporosis. This is a signal to pay attention to bone health — through diet, exercise, and sometimes medicine — to prevent the condition from worsening. If you have osteoporosis, your doctor will likely recommend treatment to slow bone loss and reduce fracture risk.
What happens after diagnosis
Once you have a diagnosis, your doctor will talk with you about treatment options. For osteopenia, the first step is usually lifestyle changes: eating more calcium and vitamin D, doing weight-bearing exercise like walking or strength training, and avoiding smoking and excess alcohol. You may not need medicine at this stage.
For osteoporosis, your doctor will likely recommend medicine along with lifestyle changes. The most common first-line medicines are bisphosphonates — drugs like alendronate (Fosamax), risedronate (Actonel), or ibandronate (Boniva) — which slow bone loss. These are taken by mouth once a week or once a month. Other options include hormone-related medicines, injectable medicines, or monoclonal antibodies, depending on your age, sex, and other health conditions.
Your doctor may also order blood tests to check your calcium, vitamin D, and kidney function, since these affect how your bones respond to treatment. If you have had a recent fracture, your doctor will want to know how it happened — a fracture from a minor fall (like stepping off a curb) is a sign of weak bones and changes how aggressively your doctor treats the condition.
When to get screened and how often
The U.S. Preventive Services Task Force recommends DEXA screening for all women 65 and older and all men 70 and older, regardless of risk factors. Women between 50 and 65 and men between 50 and 70 should be screened if they have risk factors like a family history of osteoporosis, low body weight, smoking, or long-term steroid use.
If your first scan is normal, you may not need another for 10 years. If you have osteopenia, your doctor will usually repeat the scan every 1 to 2 years to watch for changes. If you have osteoporosis and are being treated, your doctor may repeat the scan every 2 years to see whether the medicine is working.
If you have had a fracture, your doctor may order a scan sooner, even if you were screened recently. A new fracture can change the treatment plan.
Other tests that may go with your DEXA scan
Your doctor may order additional tests to understand your bone health more fully. A vertebral fracture assessment (VFA) is an extra image taken during your DEXA scan that checks for small fractures in your spine that you may not have felt. This is especially useful if you have lost height or have a curved upper back.
Blood tests can reveal whether something else is causing bone loss — such as low vitamin D, thyroid problems, or kidney disease. Your doctor may check your vitamin D level, calcium, phosphorus, and alkaline phosphatase. If you are a woman past menopause, your doctor may also measure a bone turnover marker — a blood or urine test that shows how fast your body is breaking down and rebuilding bone.
These extra tests are not always needed, but they help your doctor decide whether you need treatment and which medicine might work best for you.
What to expect during the DEXA scan
Wear comfortable, loose clothing without metal buttons, zippers, or snaps — metal interferes with the X-ray image. You can wear a hospital gown if needed. Remove jewelry, watches, and glasses. The technician will position you on a padded table and may place a pillow under your knees for comfort.
The machine has an arm that moves slowly over your body, taking images. You will feel nothing — there is no pain, no injection, no contrast dye. You must lie still for the scan, but you can breathe normally. The whole appointment usually takes 30 minutes, including check-in and paperwork.
You can return to your normal activities right away. There are no side effects from the scan itself. If you are pregnant or think you might be, tell the technician before the scan, since X-rays are not recommended in pregnancy.
Questions to ask your doctor
When you get your results, ask your doctor these questions to understand what comes next:
- What is my T-score, and what does it mean for my bones?
- Do I need medicine, or can I manage this with diet and exercise?
- What calcium and vitamin D should I be getting each day?
- What type of exercise is safest for my bones?
- When should I have my next bone density scan?
- Are there any other tests I should have to understand why my bones are weak?
- What are the side effects of the medicine you are recommending, and how long will I need to take it?
Frequently Asked Questions
Can osteoporosis be diagnosed without a DEXA scan?
No. Osteoporosis has no symptoms — you cannot feel weak bones — so a DEXA scan is the only way to know for certain whether you have it. A fracture from a minor fall is a strong sign that your bones are weak, but your doctor will still order a DEXA scan to measure the severity and guide treatment.
What if I cannot afford a DEXA scan?
Medicare covers DEXA screening for women 65 and older and men 70 and older at no cost to you. Most private insurance also covers it, though you may have a copay. If cost is a barrier, ask your doctor's office about low-cost or free screening programs in your area, or contact your local health department.
Is a DEXA scan safe?
Yes. The radiation dose from a DEXA scan is very small — about one-tenth of a chest X-ray. The scan is safe to repeat every 1 to 2 years if your doctor recommends it. The only people who should not have a DEXA scan are pregnant women, since any X-ray in pregnancy is avoided unless medically urgent.
What does a negative T-score mean?
A negative T-score does not mean something is wrong with you — it is just how the scale works. The minus sign shows that your bone density is lower than a healthy 30-year-old's. A T-score of -1.5 is better (stronger bones) than a T-score of -2.5, even though -1.5 is a larger negative number.
Can I have osteoporosis and not know it?
Yes. Osteoporosis causes no pain or symptoms until a bone breaks. Many people discover they have it only after a fracture from a minor fall. This is why screening is important for people over 65 — catching weak bones before a fracture happens gives you time to start treatment and prevent serious injury.