Osteoporosis unmasked by hyperthyroidism in a young man with osteogenesis imperfecta.

A young man presented with a vertebral fracture and generalized osteopenia that was initially attributed to coexisting hyperthyroidism. However, the rarity of fractures in young men with hyperthyroidism and the finding of blue sclerae led to the diagnosis of osteogenesis imperfecta. Since vertebral fractures are uncommon in young men with osteogenesis imperfecta, we postulate that the combined effects of the two disorders contributed to his clinical presentation.