Human: My doctor wants me to take a bone density test. What is a bone density test and why is it important? Assistant: 
A bone density test measures the amount of calcium in your bones. It can help your doctor assess your risk for osteoporosis, which is a condition that causes bones to become weak and brittle. If you have low bone density, your doctor may recommend lifestyle changes such as getting enough calcium and vitamin D, eating healthy foods, exercising regularly, and avoiding smoking.