Osteopenia is diagnosed with a bone density test called a DXA scan, which measures how much mineral your bones contain. The result is expressed as a T-score: a score between -1.0 and -2.5 means osteopenia, while -2.5 or lower means osteoporosis. A score above -1.0 is considered normal. The entire process is painless and takes about 10 to 30 minutes.
What a DXA Scan Measures
DXA stands for dual-energy X-ray absorptiometry. It works by passing two low-energy X-ray beams through your bones and measuring how much energy each beam absorbs. Denser bone absorbs more energy, so the scan can calculate your bone mineral density with high precision. The radiation exposure is very low, much less than a standard chest X-ray.
If you have the test at a hospital or imaging center, you’ll lie on a padded table while a mechanical arm slowly passes over your body. The scan typically focuses on the sites most vulnerable to osteoporosis-related fractures: the lower spine (lumbar vertebrae), the narrow neck of the thighbone near the hip joint, and sometimes the forearm. These are the locations where a fracture would have the most serious consequences, so they’re the standard measurement sites for diagnosis.
You may also encounter smaller, portable devices at health fairs or some doctor’s offices that scan your heel, wrist, or finger. These peripheral scans can flag potential problems, but they aren’t sensitive enough to formally diagnose osteopenia or track how your bones respond to treatment. If a peripheral scan suggests low bone density, a full central DXA scan of the hip and spine is the next step.
How T-Scores Work
Your DXA result is reported as a T-score, which compares your bone density to the peak bone density of a healthy 30-year-old of the same sex. A T-score of 0 means your bones match that reference perfectly. Every point below zero represents one standard deviation less dense than the reference.
- Normal: T-score of -1.0 or above
- Osteopenia: T-score between -1.0 and -2.5
- Osteoporosis: T-score of -2.5 or below
These thresholds were established by the World Health Organization and are used worldwide. Someone with a T-score of -1.2 has mild bone loss, while someone at -2.4 is close to the osteoporosis range. The lower your score within that range, the more attention your bones need.
When a Z-Score Is Used Instead
T-scores are the standard for postmenopausal women and men over 50. But if you’re a premenopausal woman, a man under 50, or a child, your result will be reported as a Z-score instead. A Z-score compares your bone density to the average for healthy people of your same age, sex, and ethnicity, which gives a fairer picture when age-related bone loss hasn’t yet started. A Z-score of -2.0 or lower is considered below the expected range and prompts further investigation into why bone density is low for your age.
Who Should Get Screened
The U.S. Preventive Services Task Force recommends routine bone density screening for all women 65 and older. Postmenopausal women younger than 65 should also be screened if they have increased risk factors, such as a family history of fractures, low body weight, smoking, or long-term use of steroid medications. For men, there is no universal screening recommendation yet because the evidence on benefits and harms is still inconclusive, though doctors may order a DXA scan for men with clear risk factors like prolonged steroid use or a history of fractures.
Your doctor may also recommend earlier screening if you’ve lost height, broken a bone from a minor fall, or have a condition known to weaken bones, such as rheumatoid arthritis, celiac disease, or hyperthyroidism.
Fracture Risk Assessment Beyond the T-Score
A T-score alone doesn’t tell the full story. Two people with the same score can have very different fracture risks depending on their age, weight, medical history, and other factors. That’s why doctors often use a tool called FRAX alongside DXA results. FRAX calculates your 10-year probability of having a major fracture by combining your bone density with clinical risk factors.
The variables FRAX considers include whether you’ve had a previous fracture, your use of oral steroids, whether you have a parent who fractured a hip, smoking and alcohol use, and conditions like rheumatoid arthritis. A newer version of the tool can also account for how recently a prior fracture occurred, your fall history over the past year, the length of your hip bone, and how long you’ve had type 2 diabetes. This layered approach helps distinguish someone with osteopenia who can safely monitor their bones from someone who needs more aggressive intervention right away.
Blood Tests to Rule Out Underlying Causes
When a DXA scan reveals osteopenia, especially in someone younger than expected, your doctor may order blood or urine tests to check whether something else is driving the bone loss. The goal is to rule out secondary causes, meaning medical conditions that weaken bones independently of normal aging.
Common tests include calcium, phosphate, and vitamin D levels to check for deficiencies or hormonal imbalances. Kidney function tests help rule out conditions that interfere with how your body processes calcium. A complete blood count can screen for blood-related disorders that affect bone marrow. Thyroid and parathyroid hormone levels are checked because overactive glands in either case accelerate bone breakdown. If your doctor suspects a less common cause, they may also test markers of bone turnover, which measure the rate at which your body is building new bone versus breaking old bone down.
These tests don’t diagnose osteopenia itself, but they can change the treatment plan entirely. If low vitamin D is the culprit, for example, correcting that deficiency may be enough to stabilize your bone density without further intervention.
What to Expect After Diagnosis
An osteopenia diagnosis doesn’t mean you’ll develop osteoporosis. It means your bones are thinner than ideal, and the trajectory matters more than any single scan. Most people with osteopenia will have a follow-up DXA scan in one to two years to see whether bone density is stable, improving, or declining. If your initial T-score is only slightly below -1.0 and you have no other risk factors, your doctor may recommend rescanning less frequently.
The practical takeaway from a DXA scan is a number you can track over time. Combined with a fracture risk assessment and any relevant blood work, that number helps you and your doctor decide whether lifestyle changes like weight-bearing exercise and calcium intake are sufficient, or whether medication makes sense. The diagnosis itself is straightforward, but the decisions that follow depend on the full picture of your bone health.