According to WebMD, there are four types of osteoporosis: idiopathic juvenile osteoporosis, primary osteoporosis, secondary osteoporosis and ostogenesis imperfecta. Primary osteoporosis is the most common form of the condition and is caused by natural bone loss that occurs in individuals over 30 years of age.
The NIH Osteoporosis and Related Bone Diseases Resource Center explains that idiopathic juvenile osteoporosis occurs in children, in most cases with no specific cause. WebMD says secondary osteoporosis occurs in children and adults and is caused by underlying medical conditions, such as rheumatoid arthritis. Ostogenesis imperfecta is a genetic condition that causes a lack of bone collagen, which in turn leads to weak bones that break easily. Additional symptoms of ostogenesis imperfecta include brittle teeth and weak muscles.