Low bone mass in children is a rare condition. It can have several causes including:
brought on by (secondary to) other medical conditions
caused by the medications used to treat these conditions
genetic disorder, such as osteogenesis imperfecta; a disease where the body cannot form bones properly
unknown cause. This is called Idiopathic Juvenile Osteoporosis (IJO)
How osteoporosis affects children
Osteoporosis in children is a serious problem, because it happens during the important bone-building years. The more bone mass we build in childhood and youth, the less likely we are to have fractures caused by fragile bones later in life.
Children with low bone mass break their bones much more easily than other children. Healthy children often break bones during sports or playground accidents. This is called traumatic fracture. Children with osteoporosis can break their bones just from falling down, or falling from a distance of their own height or less. Doctors call this an atraumatic fracture.
Secondary osteoporosis is brought on by another medical condition, or the drugs used to treat it. For example, some studies have found that children with arthritis have a lower bone mass than healthy children. Prednisone, a corticosteroid used to treat juvenile rheumatoid arthritis, may be the cause. Other corticosteroids include cortisone and deflazacort. Corticosteroids are used to treat juvenile diseases such as:
dermatomyositis, which affects skin and muscle tissue
inflammatory bowel disease
Children with serious diseases like these may be limited in their movement, or they may avoid normal physical activity because it causes pain or fatigue. Physical activity is needed to build bone mass, and this avoidance of activity increases their risk of osteoporosis.
The best course of action is to treat the underlying, or primary medical condition. If the medication is responsible for the osteoporosis, a doctor can:
prescribe the smallest, effective dose
recommend an alternative medication
Another cause of secondary osteoporosis in a small number of children is anorexia nervosa, an eating disorder.
Idiopathic Juvenile Osteoporosis (IJO)
“Idiopathic” means that we do not know what causes this form of osteoporosis. Doctors give this diagnosis after they have ruled out all other possible causes of osteoporosis in a child. First identified in 1965, it is very rare. Only 100 cases have been reported since then.
IJO occurs in healthy children just before the start of puberty – between ages eight and fourteen. It usually goes away by itself within two to four years. Permanent disability is uncommon, and normal growth resumes. Often the child’s bones catch up with the previous loss of bone growth.
Warning signs of IJO include:
fractures that are not caused by a serious trauma
fractures in the lower limbs
pain in the lower back, hips, feet, knees and ankles
The best strategy for treating IJO is to protect the spine and other bones from fracture until the disease resolves itself.
Osteogenesis Imperfecta (OI)
This is a genetic disorder – an inherited illness. It is cause by imperfectly formed collagen, which is the material that combines with calcium to form bone. Children with OI have bones that break easily, often from little or no trauma. There are many different levels of severity of the disorder. A person with OI may have as few as ten or as many as several hundred fractures in a lifetime. Osteogenesis imperfecta is very rare.