A loss of bone density causes osteoporosis. When the body loses bone faster than it can make more, the bones become weaker over time. This leads to a risk of fractures.

Healthcare professionals can check a person’s bone density using a special X-ray. For females in the postmenopausal period or males over 50 years old, the result is a T-score, which shows the difference between a person’s current bone density and the bone density of a younger adult.

For people who are in premenopause or younger than age 50, the result will be a Z-score, which compares their bone density to that of other people of the same age, sex, and ethnicity.

Keep reading to learn more about osteoporosis bone density, including the testing process, what the scores mean, and whether people can measure bone density at home.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Bone density is a measurement of bone strength.

Bones are naturally porous, meaning they contain tiny holes. Stronger bones have fewer holes because they contain larger amounts of minerals such as calcium. Weaker bones have more holes and contain smaller amounts of minerals.

Like other cells in the body, the cells that make up bones grow, mature, and die. As a result, the body is constantly making more cells to replace the old ones.

During childhood and adolescence, bone grows faster than it breaks down, and bone density and strength increase over time. In adulthood, this process becomes more balanced, resulting in stable bone density. But in older age, the replacement of bone cells slows down, resulting in a loss of bone density over time.

Low bone density, or osteopenia, can also occur due to:

  • hormonal changes
  • nutritional deficiencies
  • certain medical conditions
  • a sedentary lifestyle

A loss of bone density can lead to osteoporosis. This occurs when bones become very weak, resulting in a higher risk of fractures.

In people with osteoporosis, the bone remodeling process becomes imbalanced. The osteoclasts — cells that degrade bone — become overactive. This causes excessive bone resorption.

Meanwhile, the osteoblasts — cells that create bone — become less active. This imbalance leads to a net loss of bone mass and density over time.

The most common sites for osteoporosis-related fractures are the spine, hips, and wrists. These fractures can cause severe pain, disability, and a decline in overall quality of life.

Bone density testing helps healthcare professionals diagnose osteopenia or osteoporosis. A common testing method is dual-energy X-ray absorptiometry (DEXA).

During a DEXA scan, a special X-ray machine passes low energy X-rays through specific areas of the body, such as the hip, spine, and forearm. The device measures the amount of X-ray energy that passes through the bone, providing precise information about bone density.

To diagnose osteoporosis, doctors also consider clinical risk factors for the condition, including:

  • age
  • sex
  • personal medical history, such as previous fractures
  • family history of osteoporosis

Experts recommend screening for osteoporosis in:

The results of a DEXA scan provide measurements known as T-scores or Z-scores.

A T-score shows how much a person’s bone mass differs from the bone mass of an average healthy young adult. Doctors use this measurement for males over age 50 and females in postmenopause.

Here is what the results mean:

  • 1 or more: healthy bone density
  • Between –1 and –2.5: osteopenia, which means bone density is low
  • –2.5 or lower: osteoporosis, which means bone density is significantly below average

Z-scores compare an individual’s bone density to that of other people of the same age, sex, and ethnicity. Doctors use this type of score in younger adults to evaluate bone density that is not the result of natural aging.

A result of –2.0 or less may indicate osteoporosis. This could be due to a medical condition or medication.

No, it is not possible to measure bone density at home.

While various health monitoring devices are available for personal use, such as fitness trackers and blood pressure monitors, assessing bone density requires more sophisticated tools and techniques.

Some commercially available devices claim to provide bone density measurements at home using ultrasound technology. However, these devices often provide estimates or indirect measures of bone health. They are not as accurate or reliable as DEXA scans at a medical facility.

A person can take steps to prevent weakened bones, including:

  • getting enough calcium and protein from the diet
  • getting adequate vitamin D from sunlight, foods, or supplements
  • getting regular exercise, including weight-bearing exercises
  • limiting alcohol consumption
  • quitting smoking, if relevant

It may also be helpful to treat any underlying health conditions that can affect bone density before they contribute to osteoporosis. For example, people with low estrogen levels may benefit from hormone replacement therapy.

Additionally, it is important that a person learn the side effects of any medications they take. If a medication could affect bone strength, a person can consult a doctor about the potential risk and how to manage it.

While osteoporosis is irreversible, specific measures can slow down or halt the progression of bone loss. This involves a multifaceted approach that may include:

  • Nutrition: Adequate intake of calcium, vitamin D, and other essential nutrients supports bone density. People can get calcium from foods such as dairy products, leafy greens, and fortified cereals or breads. People can get vitamin D from sunlight and certain foods, such as oily fish.
  • Exercise: Regular exercise, particularly weight-bearing and resistance exercise, has a positive effect on bone density. Activities that increase balance, such as yoga and tai chi, can help prevent falls.
  • Lifestyle changes: If a person smokes, stopping smoking can increase their bone mineral density. It is also important to avoid drinking alcohol excessively.
  • Medications: Certain medications, such as bisphosphonates, can help slow down bone loss and improve bone density. These medications work by either inhibiting bone breakdown or promoting bone formation. Other medications that may help include hormone therapies, estrogen modulators, and calcitonin.

While interventions can help improve bone density to some extent, they may not fully restore bone density to typical levels. The degree of improvement in bone density can depend on several factors, such as:

  • the severity of osteoporosis
  • a person’s individual response to treatment
  • a person’s adherence to recommended strategies

Osteoporosis results from a loss of bone density. Bone density testing, such as a DEXA scan, is critical for diagnosing the condition, assessing fracture risk, and monitoring treatment effectiveness.

T-scores and Z-scores evaluate bone density in relation to a healthy young adult. T-scores compare the bone density of older adults to that of younger adults, while Z-scores compare the bone density of similar younger adults.

While it is not possible to reverse osteoporosis, interventions such as exercise, dietary changes, and medications can help slow down bone loss.