Osteoporosis in children is rare. It's usually results from asthma, cystic fibrosis, or other diseases that are treated with long-term steroids. Anticonvulsant drugs used to manage epilepsy, or used to manage mania in bipolar disorder, and other conditions may also affect how the body uses calcium and vitamin D metabolism and weaken the bones. Some children get osteoporosis with no clear cause. It's called idiopathic juvenile osteoporosis. It usually goes away on its own within 2-4 years.