What is the Difference Between Bone Mass and Bone Density

The main difference between bone mass and bone density is that the bone mass refers to the amount of bone tissue in the skeleton whereas the bone density refers to the mineral mass per unit volume of bones. Furthermore, bone mass increases until age 30 while bone density serves as an indicator of osteoporosis and risk of fractures.

Bone mass and bone density are two measurements that indicate bone quality. Osteoporosis is a bone disease, which occurs with the loss of too much bone from the body. 

Key Areas Covered

1. What is Bone Mass
     – Definition, Facts for Healthy Bones
2. What is Bone Density
     – Definition, BMD Tests, and Results
3. What are the Similarities Between Bone Mass and Bone Density
     – Outline of Common Features
4. What is the Difference Between Bone Mass and Bone Density
     – Comparison of Key Differences

Key Terms

BMD Tests, Bone Mass, Bone Density, Bone Quality, Osteoporosis, T-Score

What is Bone Mass

Bone mass is the amount of bone tissue in the body. Until about 30 years, bone tissue generally increases. After that, it starts decreasing slowly. It is important to keep the bones strong and healthy as possible. The peak bone mass of a particular individual is affected by the gender, race, hormonal factors, nutrition, physical activity, and lifestyle. A healthy diet can be a good factor for strong bones. Calcium, vitamin D, vitamin K, potassium, and magnesium are the essentially contributing for healthy bones.

• Bones are made up of calcium and phosphorus. Calcium can be taken from dairy products, fish with bones (sardines, canned salmon), beans, leafy greens such as spinach, oatmeal, etc.
• Vitamin D is required for the absorption of calcium. It occurs in eggs, shrimp, and fatty fish.
• Potassium helps in strengthening bones with calcium by neutralizing acids that break down calcium. It is available in sweet potatoes, potatoes, oranges, bananas, and yogurt.
• Magnesium makes both calcium and vitamin D to work efficiently. Magnesium is available in spinach, tomatoes, potatoes, sweet potatoes and artichokes.
• Vitamin K and C are also good for the health of bones, which can be obtained by eating leafy greens and fruits.
  

  Figure 1: Fluctuation of Bone Mass with Age

Also, alcohol consumption, caffeine, and smoking affect the bone mass badly. Alcohol interferes with vitamin D while both caffeine and smoking interfere with calcium.

What is Bone Density

Bone density or bone mineral density (BMD) is a measurement of the quality of bones and it indicates the mass of minerals per unit volume of bones. Measuring bone density allows the determination of:

• Osteoporosis;
• Risk for fracture and
• Response to osteoporosis treatment

The most common BMD test is the central DXA test or central dual-energy x-ray absorptiometry, which measures the bone density at the spine and hip. The other BMD tests are the peripheral BMDs done in the lower arm, wrist, heel or finger.

During the interpretation of bone density test results, the values of bone mineral density of a particular individual are compared with a standard to give a score. The most common score system is the T-score. T-score involves comparing the bone density of the individual with the peak BMD of a healthy, 30 years old adult. The variation is given by standard deviations (SDs). Table 1 shows the observable results of the T-Score test.

T-Score Values

Figure 2: Bone Density of Normal and Osteoporotic Bones

Bone density results can also be interpreted as areal density in g cm⁻² or Z-score in comparison to the age-matched normal.

Similarities Between Bone Mass and Bone Density

• Bone mass and bone density are two types of measurements that determine the quality of bones.
• Both have to be maintained within the normal range for healthy bones.
• They help in the diagnosis of osteoporosis.

Difference Between Bone Mass and Bone Density

Definition

Bone mass refers to the amount of bone tissue in the skeleton while bone density refers to the mineral density of bones.

Units

Bone mass is expressed in kilograms while bone density is expressed as mass per unit volume.

Significance

A healthy diet is good for maintaining healthy bones while bone density test results help in the determination of osteoporosis.

Conclusion

Bone mass is the amount of bone tissue in the body, which is interpreted in kilograms while bone density is the mineral mass per unit bone volume. Both types of tests help to determine the bone quality. The main difference between bone mass and bone density is the type of measurement and their significance in bone quality determination.

Reference:

1. “Bone Mass.” Tanita, Available Here
2. “Bone Mass Measurement: What the Numbers Mean.” National Institutes of Health, U.S. Department of Health and Human Services, Available Here

Image Courtesy:

1. “615 Age and Bone Mass” By Anatomy & Physiology, – OpenStax College (CC BY 3.0) via Commons Wikimedia 
2. “Osteoporosis Locations” By BruceBlaus – Own work (CC BY-SA 4.0) via Commons Wikimedia