Although it isn't common, children sometimes have osteoporosis. Osteoporosis is a disease that causes loss of bone mass. In children, reasons for this include poor diet, use of steroid medications, or specific bone disease. In some cases, osteoporosis develops with no known cause and goes away over time. This is called idiopathic juvenile osteoporosis.

There is a disease that is sometimes present at birth called osteogenesis imperfecta. It causes fragile bones due to osteoporotic changes in the bones of children. Vitamin D deficiency from poor diet, inadequate sun exposure, or cancer can cause rickets, a form of bone softening and wasting.