What is a bone mineral density test and do I need one?

Last Updated on September 24, 2026

It is estimated about 54 million Americans are living with osteoporosis and low bone mass, according to the Bone Health & Osteoporosis Foundation. More alarming, studies suggest about one in two women and up to one in four men age 50 and older will break a bone due to osteoporosis.

As we age, we tend to lose more bone mass than our bodies can form — and the rate at which we lose bone mass speeds up once we hit middle age. With osteoporosis, your bones become porous, weak, and brittle, putting you at risk for fractures or broken bones.

This silent condition is responsible for an estimated two million broken bones per year. Unfortunately, almost 80 percent of adults who suffer bone breaks have not screened for osteoporosis.

That is where a bone mineral density (BMD) screening can help. It is the best way to diagnose and monitor osteopenia (decreased bone mass) and osteoporosis (thin, weak bones). Healthcare providers use the BMD screening, which is painless, requires no medication, and exposes you to very little radiation to:

• Confirm a diagnosis of osteopenia or osteoporosis
• Determine the rate of bone loss over time by comparing previous scans (if available)
• Estimate the risk of future fractures
• Monitor the effectiveness of osteoporosis treatment

The most common and accurate BMD screening uses a unique X-ray — called a dual-energy X-ray absorptiometry, or DEXA, to measure how much calcium and other bone minerals are packed into an area of bone. Typically, the spine, lower arm, and hip are measured. The higher the mineral content, the denser (and stronger) your bones are and less likely to break. A DEXA scan remains the gold-standard screening for measuring bone mineral density for diagnosing osteoporosis.

BMD screenings are more precise than standard X-rays and can find issues much earlier, so treatment can begin sooner, hopefully before complications arise.

Bone Mineral Density (BMD) screening results

BMD screening results are compared to two norms: healthy young adults (T-score) and age-matched adults (Z-score).

For your T-score, results are measured against a healthy 25–35-year-old adults of your same sex and ethnicity. Positive T-scores indicate your bones are stronger than normal, and negative T-scores indicate they are weaker.

The National Institute of Health offers the following guidelines for bone density scores:

• Normal is a T-score of -1 and above
• Osteopenia (Low bone mass) is -1 to -2.5
• Osteoporosis is -2.5 or below

In addition, your BMD result is measured against an adult of your own age, sex, race, height, and weight. This is called your Z-score, which is calculated in the same way as a T-score.

Who needs a bone mineral density screening?

Osteoporosis is more common in women, but men can develop the condition, too. Your healthcare provider may order a BMD screening if there is a suspicion your bones are becoming weaker, you show symptoms of osteoporosis, or you have reached the age when preventive screening is recommended.

You should discuss a BMD screening with your healthcare provider beginning at age 65 for women and 70 for men; however, for men, healthcare providers may use individual judgment rather than a universal screening recommendation. Most people under the age of 65 do not need a BMD screening unless they are at an increased risk for osteoporosis or fractures. Common risk factors include:

• All women 65+ who are post-menopausal and do not take estrogen
• Smoking and excessive use of alcohol
• Family history of osteoporosis
• Use of certain medications, such as steroids
• Low body mass index (BMI) or poor nutrition
• Certain chronic conditions, such as rheumatoid arthritis, Type 1 diabetes, liver or kidney disease, or hyperthyroidism

Prompt treatment is key to preventing bone fractures. The complications of broken bones due to osteoporosis are often severe, particularly for elderly adults. So, the earlier osteoporosis is diagnosed, the sooner you can begin treatment to improve your condition or keep it from getting worse.

Bone health information that is important today:

• Adequate calcium intake
• Adequate vitamin D
• Regular weight bearing and resistance exercises
• Fall prevention
• Smoking cessation and limiting excessive alcohol use