Q: I recently suffered a stress fracture of my left leg and my doctor told me it might be because my bones look a little thin on an X-ray. He wants to do lots of blood tests but my mother says only older women have this problem and that at 16, I have nothing to worry about. What do you think?
A: We think you're right to be concerned. Although we're not sure what your doctor means by "thin bones," we assume he or she is referring to a decreased amount of calcium in the bone structure. This condition is referred to as "osteopenia" when it occurs among adolescents and young adults and "osteoporosis" when applied to older adults.
Your mother is correct when she says it is a common condition in the elderly, but we also know that osteopenia does occur among adolescents, particularly young women. Since an individual's bone mass decreases as she ages, it is important that adolescents maintain well mineralized bones to prevent future problems. Regardless of age, people with decreased bone density are at risk for a variety of fractures in the legs and spine.
There are a number of possible explanations for what your doctor saw on an X-ray. Some teen-agers simply do not consume the recommended amount of calcium (about 1,200 milligrams per day) needed for good bone formation. This is particularly important during adolescence when the skeleton grows very rapidly.
Others, responding to the cultural pressure to be thin, restrict calories and the foods (like dairy products) that are high in calcium. Young women with irregular menstrual periods may lack the hormonal stimulation needed to assure that the calcium she consumes is deposited appropriately in bone. Intense exercise may cause or exacerbate problems with irregular periods. There are some other diseases that can cause osteopenia and it appears your doctor is proceeding appropriately.
When your evaluation is complete, you'll want to sit down with your doctor and make sure you understand the results. Don't be afraid to ask questions. It's important to make sure your bones develop normally.
Dr. Wilson is director of general pediatrics at the Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.