Download Bone age and Olympian dreams

MIND&BODY
| TUESDAY, AUGUST 30, 2016 | THE STRAITS TIMES |
DocTalk
Bone age and
Olympian dreams
Bone-age assessments usually check on
height growth and precocious puberty
Cindy Ho
Joseph Schooling’s Olympic
gold-medal win and his journey
to get there has sparked off
a discussion about bone age
among readers and parents.
His parents had taken him
for a bone-age assessment
when he was 11 years old.
This was to gauge how tall
he would eventually be and
to see if that augured well
for a competitive sports career.
However, the usual requests
for bone-age assessment that
I see in my clinic are typically
over concerns of height growth
and precocious puberty.
The commonest scenario is a
worried parent with a 12-year-old
who appears much shorter
than his peers.
Oftentimes, when a bone-age
assessment is done on such a child,
the age of his bones is more than
two years younger than the
child’s actual age. This is called
constitutional growth and pubertal
delay (CGPD) and is a normal
variant among children.
Such children appear short
in their younger years as they have
a delayed maturation and will
have an extra two or more years
to grow after their peers have
stopped growing.
Sometimes, their height
eventually exceed those of
their other classmates.
A bone-age test is an X- ray
assessment of the degree of
maturation of a child’s bones.
As a person grows from birth
through childhood and puberty,
and completes growth as a young
adult, skeletal bones change
in size and shape.
The bone age of a child is the
average age at which children reach
this stage of bone maturation.
A child’s current height and
bone age can thus be used to
predict his adult height.
However, children do not
mature at exactly the same time.
Just as there is wide variation in
the normal population for when
tooth eruption or menstruation
occur, the bone age of a healthy
child may be a year or two ahead,
or delayed, compared to actual age.
For most people, their bone age
is similar to their biological
or chronological age and may
differ by only a few months.
For others, their bone age could
be a few years older or younger.
The assessment involves a single
X-ray of the left hand, fingers
and wrist. The bones in the X-ray
are compared to a standard atlas
of bone development.
Different small bones in the
wrist start appearing as the child
gets older and the shapes of
various bones change.
Growth plates (gaps between
bones) get narrower with age. A
growth plate is a hyaline cartilage
plate at each end of a long bone.
These are found in children
and adolescents. In adults who
have stopped growing, the plate
is fused and replaced by a line.
Typically, paediatric
endocrinologists order bone-age
X-rays to evaluate children for
advanced or delayed growth
and physical maturation.
A worried father once brought
his 12-year-old daughter to see me.
His burning question was how
much taller she would be and
whether there was something
that could be done. At that age,
she was already as tall as him,
standing at 1.75m.
He was worried that it would
be difficult for her to find
a husband taller than her.
Her bone age was found to be
already at 15 years. Her case is one
of familial tall stature, because
she has relatives who are tall.
Based on her bone age, which
showed that she would have only
another year or so to grow and
at a very slow rate, I could reassure
her father that her growth
was almost done.
Then there are children who go
into earlier puberty than average.
They will have a bone age that is
more than two years ahead of
their actual age. Because they
experience pubertal growth spurts,
they appear taller than many
of their peers. However, as they
complete puberty and their bones
fuse, they stop growing taller
while their friends continue
doing so. This results in a
shorter stature as an adult.
I have a very young patient
who went into precocious puberty
due to a condition resulting in
excess sex steroid production.
This caused his bones to advance
in age. His bone age was 13 years old
when he was only five.
His predicted height was only
1.4m, which is very short for a boy.
He has been started on hormone
treatment for his disease that will
reduce the excess sex steroid
production.
In some situations of precocious
puberty, it is sometimes
recommended that puberty be
blocked with medications to “buy”
time for the child to grow taller.
Girls who have not gone into
puberty by age 13, and boys by
age 14, are said to have delayed
puberty and will be referred
for further assessment.
A bone-age assessment in this
case will determine if the bones are,
in fact, younger than the patient’s
chronological age. If so, this is
often due to constitutional growth
and pubertal delay and all that
needs is “masterly inactivity”.
That is, to do nothing and observe
when puberty comes about.
There is a possibility that puberty
does not happen and it could be due
to missing messengers (hormones
called LH/FSH) for puberty to start.
Then, we need to give hormone
treatment to initiate puberty.
Most parents get a little worried
about the variant between their
child’s actual age and bone age,
especially when the difference
is more than two years.
I always tell the parents that
it is important to know that
advanced or delayed bone age
does not always indicate disease.
Take, for example, a boy whose
bone age is delayed by three years.
While he may be shorter than
his peers now, it also means that
he will continue to grow for three
years after his peers have stopped.
Hence, bone age has to be
considered in the context of
broader considerations such as
delayed or advanced puberty,
tall or short stature and chronic
illness, in order to draw
meaningful conclusions.
[email protected]
• Dr Ho is an associate consultant
in the division of paediatric
endocrinology at the National
University Hospital. She completed
her paediatric endocrinology
fellowship training at the Royal
Children’s Hospital in Melbourne,
Australia. She sees all paediatric
endocrine conditions but has special
interests in bone health and growth
in children, and late effects in
children who have survived cancer.
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