Bone age, also called skeletal age, is determined by taking an X-ray (picture) of the left hand and wrist. There are many bones and growth plates (openings between your bones) in your hand and wrist that allow you to grow. The doctor can tell from the X-ray how much time a child has left to grow.
Your body makes many hormones that change the way your X-ray looks as you get older. As you age, your body makes more and more hormones. These hormones make the size of your growth plates shrink. They also cause changes in your bones. Sometimes your body does not make the right amount of hormones for your real age. When this happens, your bone age might be older or younger than your real age. A radiologist will look at all of these changes when he/she looks at the X-ray and gives a report.
If there is a difference between your child's real age and the bone age, the X-ray will help your doctor decide how to care for your child.