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The two main
endocrine disorders that cause short stature are growth hormone
deficiency and thyroid deficiency.
Growth Hormone Deficiency
Diagnosis:
If MPHD (see below) at birth. If solely GHD possible by 18 months. 80% of
cases of GHD should be diagnosed by school entry.
Treatment:
Growth hormone (GH) replacement therapy
Growth Hormone Deficiency (GHD) is generally due to the pituitary gland being unable
to produce sufficient GH to generate the growth process. GHD does not
affect intrauterine growth, at least to an extent measurable by birth
weight or length, but from the second year of life growth is slower
than normal and occasionally growth failure commences from birth. Most
cases of growth hormone deficiency are idiopathic, meaning of unknown
origin. Idiopathic growth hormone deficiency occurs, it seems, in
about 1 in 3800 births.
GHD may also be
hereditary, at least in some cases. About 3% of children with GHD have
brothers or sisters who also have the disorder. In a very few families
one of the parents is affected. The deficiency is two to three times
more common in boys than in girls, for reasons quite unknown
Children with GHD are
small with normal skeletal proportions, facial appearance and
intelligence. They tend to be overweight
(this reduces during GH treatment) and they often have a delayed bone
age. The diagnosis is confirmed by measuring the level of growth
hormone production in response to a stimulation test which normally
requires a morning in hospital. The deficiency may be of growth
hormone only, although other pituitary hormones may also be affected (MPHD).
The associated hormone deficiencies are:
- thyroid-stimulating hormone (TSH)
- the gonadotrophins - follicle stimulating hormone (FSH) and lutenising hormone (LH)
- adrenal-stimulating hormone (ACTH) is much less frequently involved,
but the deficiency of this hormone is extremely important to detect.
If there is a
deficiency of TSH, thyroxine is given, and if gonadotrophin deficiency
becomes apparent at the time of puberty (which is usually late in
growth hormone deficient children), the sex hormones have also to be
given and treatment can initiate sexual maturation. Very occasionally
antibodies develop to the injected growth hormone treatment and cancel
out the effects of treatment but this is extremely rare with more
modern biosynthetic human growth hormones; otherwise side-effects are
unusual.
The treatment of
growth hormone deficiency has been recognised since the first patient
was given human growth hormone by Raben in 1958 in Boston, USA,
although since October 1985, biosynthetic growth hormone has replaced
the pituitary derived hormone in the UK. Provided treatment is started
at a reasonably early age (at least before age 6 years) the results
are nearly always excellent (even at later stages results are
sometimes spectacular, but not invariably). Catch-up-growth occurs
following initial treatment and thereafter a normal growth rate is
usually maintained.
Adults with growth
hormone deficiency may require growth hormone treatment for metabolic
reasons after they have stopped growing. The daily doses are usually
much lower than those given to children. The lack of growth hormone
may contribute to symptoms of general tiredness, weakness and weak
bones (osteoporosis). Growth hormone is an approved treatment for
adult GHD.
Oncology Patients
Every child who has had oncology treatment is a possible candidate for growth hormone.
Growth hormone
deficiency can also result from damage to the part of the brain
controlling the pituitary gland, the pituitary itself, or both. Some
tumours are benign, i.e. not cancerous, and the one that is the most
common in the pituitary region is called a craniopharyngioma. This is
not technically a brain tumour at all, but part of a piece of mouth
epithelium (the lining of the mouth) pinched off and left behind
during the development of a baby while still in the womb. A
craniopharyngioma can be identified by taking a skull-ray, MRI or by
computer assisted tomography of the brain. They are usually surgically
removable. Occasionally, they recur, but are removable again.
The child with a
pituitary tumour occasionally comes to the physician with the sole
complaint of short stature, but more usually the symptoms are
neurological e.g. headaches, nausea, affected vision. Treatment may
involve radiotherapy and / or surgical removal of the tumour after
which the child may develop a combination of pituitary hormone
deficiencies.
Most, though not
all, have growth hormone deficiency. They are treated with growth
hormone, often in conjunction with thyroxine, cortisol
(hydrocortisone) and, at the time of puberty, gonadotrophins or sex
hormones. In addition such children may need replacement of the
posterior pituitary hormone, vasopressin, in order to restore a normal
fluid balance in the body.
Hypothyroidism
Diagnosis:
Congenital at birth. Late onset at any age during childhood
Treatment:
Thyroxine tablets
Lack of thyroid
gland secretion (thyroxine) may also stop normal growth occurring, as
all cells need a certain level of thyroid hormone in them in order to
function properly. Hypothyroidism may start in utero, in which
case the development of the brain is affected and diagnosis and
treatment directly after birth is a matter of urgency. The condition
can be diagnosed by measuring the levels of thyroid hormone in the
blood and this is now a routine screening test for all new-borns.
Short stature is
more usually caused by late onset of hypothyroidism, the type of
hypothyroidism that starts during childhood, often subtly. The
catch-up growth during thyroid hormone replacement treatment is marked
but, unfortunately, rarely complete.
Typical Growth Chart for Idiopathic Hypothyroidism
Typical Growth Chart for Acquired Hypothyroidism
Further Reading
For further reading, please see the following CGF Booklets;
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