Osteoporosis literally means "porous
bone." It is a disease characterized by too little bone
formation or excessive bone loss and an increase in the
risk of fractures. Osteoporosisis called a silent
disease because it progresses without any symptoms until
a fracture occurs. It usually affects people later in
life, and is most common in women after menopause.
Osteoporosis is rare among children and adolescents.
When it occurs, it is usually caused by an underlying
medical disorder or by medications used to treat such
disorders. This is called secondary osteoporosis
. It may also be the result of a genetic disorder such
as osteogenesis imperfecta . Sometimes there is
no identifiable cause of juvenile osteoporosis. This is
known as idiopathic juvenile osteoporosis (IJO).
No matter what causes it, juvenile osteoporosis can be a
significant problem, as it occurs during the prime
bone-building years. From birth through young adulthood,
up to about 30 years of age, bone formation
predominates, resulting in a steady accumulation of bone
mass. Most bone mass, in fact, is accumulated by early
adulthood (Matkovic, 1994; Teegarden, 1995). After the
mid-thirties, bone mass typically begins to decline
slowly, speeding up in women after menopause. Both
genetic and lifestyle factors (e.g., diet and physical
activity) influence the development of peak bone mass
and the rate at which bone is lost.
Secondary osteoporosis can affect
both adults and children, and results from an underlying
(primary) disorder or therapeutic activity. Juvenile
arthritis (JA) provides a good illustration of the
possible causes of secondary osteoporosis.
In some cases, the disease process itself can
cause osteoporosis. For example, some studies have found
that children with JA have bone mass that is lower than
expected, especially near the arthritic joints.
Sometimes, medication used to treat the primary
disorder may reduce bone mass. For example, certain
drugs such as prednisone (glucocorticoids) used to treat
JA may affect bone mass. Finally, some behaviors
associated with the primary disorder may lead to bone
loss or a reduction in bone formation. For example, a
child with JA may avoid physical activity (which is
necessary for building and maintaining bone mass)
because it may aggravate his or her condition or cause
In cases of secondary osteoporosis, the best course of
action is to identify and treat the underlying disorder.
In the case of medication-induced juvenile osteoporosis,
it is best to treat the primary disorder with the lowest
effective dose of the osteoporosis-inducing medication.
If an alternative medication is available and effective,
the child's doctor may also consider prescribing it.
Medications and Behaviors That May Affect Bone Mass:
Anti-convulsants (e.g., for epilepsy)
Corticosteroids (e.g., for rheumatoid arthritis,
Immunosuppressive agents (e.g., for cancer)
Prolonged inactivity or immobility
Inadequate nutrition (especially calcium,
Excessive exercise leading to amenorrhea
Idiopathic juvenile osteoporosis (IJO)
is diagnosed after excluding other causes of juvenile
osteoporosis (i.e., primary diseases or medical
therapies known to cause bone loss, as discussed above).
IJO was first identified in the medical literature in
1965 (Dent and Friedman). Since then, fewer than 100
cases have been reported.
This rare form of osteoporosis typically occurs in
previously healthy children just before the onset of
puberty. The average age of onset is between 8 and 14
years, but it may also occur in younger children during
periods of rapid growth. The most notable feature of IJO
is that it can remit within two to four years.
The first sign of IJO is usually
pain in the lower back, hips, and feet, often
accompanied by difficulty walking. There may also be
knee and ankle pain, and fractures of the lower
extremities . Physical deformities may be
present, such as kyphosis (abnormal curvature of the
thoracic spine), loss of height, a sunken-chest, or a
limp. These physical abnormalities are sometimes
reversible after the IJO has run its course.
X-rays of children with IJO often show low bone density,
fractures of the weight-bearing bones, and collapsed or
misshapen vertebrae. However, conventional X-rays may
not be able to detect osteoporosis until significant
bone mass has already been lost. Newer methods such as
dual energy x-ray absorptiometry (DXA), dual photon
absorptiometry (DPA) and quantitative computed
tomography ("CAT scans") allow for earlier and more
accurate diagnosis of low bone mass.
Early diagnosis of IJO is
important, although there is no established medical or
surgical therapy for the disease. In fact, there may be
no need for treatment, as IJO usually resolves
spontaneously. The basic strategy of treatment is to
protect the spine and other bones from fracture until
remission occurs. This is accomplished through
supportive care, which may include physical therapy, use
of crutches, and/or avoidance of unsafe weight-bearing
activities. Some medications that are used to treat
osteoporosis in adults have also been given children
with IJO. Examples include bisphosphonates and
calcitriol. The physician may try a medical therapy if
the problem is severe and not resolving spontaneously.
As mentioned above, patients with
IJO can experience a complete recovery within two to
four years. Growth may be somewhat impaired during the
acute phase of the disorder, but normal growth
resumes--and catch-up growth often occurs--thereafter.
In some cases, IJO can result in permanent disability
such as kyphoscoliosis or even collapse of the rib cage.
Distinguishing IJO from Osteogenesis Imperfecta
Osteogenesis imperfecta (OI) is a
genetic disorder characterized by bones that break
easily, often from little or no apparent cause. Most
forms of OI are caused by imperfectly formed bone
collagen, the result of a genetic defect. There are at
least four distinct forms of the disorder, representing
extreme variation in severity from one person to
another. For example, a person may have as few as ten or
as many as several hundred fractures in a lifetime.
While the prevalence of OI in the United States is not
known, the Osteogenesis Imperfecta Foundation estimates
that a minimum of 20,000 and as many as 50,000 are
affected by this disorder.
The clinical features of OI vary greatly from person to
person; there is also great variation in their severity.
Many individuals with OI have only some-not all-of the
clinical features. Children with milder OI, in
particular, may have few obvious clinical features of
The most common features of OI include:
bones that fracture easily
family history present in about 75% of cases
small stature common
sclera ("whites" of the eyes) may have a blue,
purple, or gray tint
possible hearing loss
possible brittle teeth
The features that most often
distinguish OI and IJO are the family history and
blue, purple, or gray sclera commonly found in
cases of OI.
« Secondary osteoporosis is best
addressed by treating the primary disorder and/or using
the lowest effective dose of an osteoporosis-inducing
« Idiopathic juvenile osteoporosis is quite rare. It is
often suspected after a series of fractures not caused
by serious trauma. The condition usually resolves itself
within two to four years, and permanent disability is
Juvenile osteoporosis can often be most
easily distinguished from osteogenesis imperfecta by the
lack of family history and the absence of blue, purple,
or gray sclera.