By Egla Rabinovich, MD, MPH and Dennis Clements, MD, PhD
When one thinks of bones, what often comes to mind are the hard, dead
bones of skeletons. However, bones are living tissues that are always
changing, even as you sit reading this! Your body is always creating
new bone cells to replace the old ones, a process that is necessary
for the bones to stay healthy and perform their three vital functions.
First, there is a structural function: bones give support to our body,
allow our legs and arms to function, and protect organs such as heart
and lungs. Second, the essential elements of blood are made in the
center, or marrow, of bones. Third, bones act as a reservoir for essential
minerals, most importantly calcium, magnesium, and phosphorus. In
fact, 99 percent of the calcium found in the human body is found in
is a unique time in bone biologynot only is there the constant
turnover of cells that occurs in adult bones, but the bones are
also growing. For this reason, childhood is our best window of opportunity
for preventing osteoporosis.
do we measure bone strength?
Osteoporosis is a disease of abnormally weak bones that increases
the risk of fractures (broken bones). One of the most common tools
used to diagnose osteoporosis is a DEXA machine. DEXA stands for
dual energy radiographic absorptiometry, which is a
specialized type of X-ray. As rays are passed over the body, they
see how much mineral is in the skeleton and also measure
the area of the skeleton. The result is called the bone density.
While the World Health Organization defines osteoporosis as having
a bone density that is 2.5 standard deviations below that
seen in a healthy normal adult, there is no accepted definition
for osteoporosis in children.
children grow, their bones grow and the corresponding bone density
rises continually during each year of growth. During the teenage
years the bone density takes a big jump; this rapid increase follows
the growth spurt and is under hormonal control. In the late teens
and early twenties, our bone density hits a maximum, called the
peak bone mass. Once peak bone mass is achieved, it
never can increase further. Thus, if bone development is adversely
affected during childhood, the potential for osteoporosis increaseseven
though we may not see fractures until 20 to 40 years later! This
is why osteoporosis during childhood is often called a silent
disease: it may be present, but the resulting fractures do not occur
until much later in life.
are risk factors for osteoporosis?
There are plenty of well recognized risk factors for osteoporosis
in the elderly: low calcium intake, inadequate vitamin D intake,
physical inactivity, race (Caucasians being more at risk than African-Americans),
female gender, being very thin, premature menopause, excessive caffeine
intake, cigarette smoking, excessive alcohol intake, medications
(especially corticosteroids such as prednisone), and family history
children, however, the risk factors are not firmly established.
It appears that children who are more physically active have increased
bone densities; a greater calcium intake has also been linked to
higher bone densities. However, teenage girls who exercise so much
that their menstrual periods go away, or who are anorexic, are at
risk for osteoporosis. Juvenile rheumatoid arthritis or juvenile
diabetes can increase the risk of osteoporosis for young people,
as can taking steroids.
and treatment of osteoporosis.
The best medicine for osteoporosis is prevention, and the time to
act is during childhood. This is what you can you do for your child
to optimize his or her peak bone mass:
sure your child takes enough calcium and vitamin D, and keep your
child active. A recent study showed that teenagers in the United
States frequently have inadequate calcium intake, and their calcium
intake is inversely correlated with soda pop intakemeaning
that the more pop they drink, the less calcium they are likely to
get! Current recommendations for calcium intake are shown in the
accompanying table. For teenagers, this translates into four servings
from the milk group daily. Milk is a nice choice for calcium because
in the U.S. milk is supplemented with vitamin D, which helps the
body utilize calcium.
Other important sources of calcium include yogurt and cheese, sardines,
canned salmon with bones, broccoli, leafy greens, all kinds of meat,
and calcium-fortified foods, such as orange juice. Vitamin D is
found in supplemented milk, but is also made by the body when skin
is exposed to sunlight. Calcium supplements are available by prescription,
but are also found in some antacids (for example, Tums and Rolaids).
Ask your doctor if your child might benefit from calcium supplementation.
If you have a strong family history of osteoporosis, or if your
child is taking steroids, ask your doctor about the possibility
of getting a DEXA scan done. Keep in mind, however, that one of
the problems with childhood osteoporosis is that treatments have
been geared towards adults. Treatment for osteoporosis in childhood
has not been established and should be considered experimental.
There is more research needed on bone health in children and prevention
or treatment of childhood osteoporosis. Until then, helping your
child prevent osteoporosis with the steps outlined above is the
best course of action.
Calcium Intake Recommendations by Age Group
Age Group Calcium Goal (mg/day)
1-3 years 500
4-8 years 800
9-18 years 1,300
19-50 years 1,000
Rabinovich, MD, MPH, is co-chief of the division of pediatric rheumatology
at Duke. Dennis
Clements, MD, PhD, is interim chair of the Department of Pediatrics
at Duke University Medical Center. For more information, visit www.dukehealth.org
information presented on this site is intended solely as a general
educational aid, and is neither medical nor healthcare advice for
any individual problem, nor a substitute for medical or other professional
advice and services from a qualified healthcare provider familiar
with your unique circumstances. Always seek the advice of your physician
or other qualified healthcare professional regarding any medical
condition and before starting any new treatment.