Summary of Human Growth Hormone Deficiency
Nov
2001: This summer the doctor seemed to think that Luke does not
have GHD, but his growth will continue to be monitored.
At
this point [Aug 2000], only a screening test has indicated that Luke has GHD; it will have
to be confirmed with a more extensive and definite test.
However, here are some notes on this condition.
Failure to Thrive
Originally diagnosed as Failure to Thrive (FTT).
This is a failure to gain height and weight.
It may be accompanied by a delay in physical, mental and social skills.
“If failure to thrive is seen in the first year of life, 60-80%
will have an organic etiology.”
Growth Hormone Deficiency (GHD)
Explanation
In some cases it is called “pituitary dwarfism.”
In any case, it is related to the pituitary gland not secreting enough GH. The causes can include a tumor in PG, absence of PG or
trauma.
“Though much smaller, these children (with GHD) have normal body
proportions and often tend to look younger than their peers.
Some may appear to be on the higher percentile in weight, though cases of
GHD have been diagnosed for children of low weight.”
“In pituitary dwarfism, the pituitary gland produces inadequate
amounts of growth hormone, which cause abnormally slow growth and short stature
with normal proportions” (Merck).
Lack of growth may be displayed at any age.
Child may appear fat (correct weight but short height) or may be
correctly proportioned (Luke).
Results if Untreated
“Children who develop a pituitary deficiency of growth hormone
at a young age will never grow normally and are destined to become dwarfs in
adulthood if untreated.”
“Learning, memory and intelligence all depend on adequate growth
hormone.” (only seen in one source; value of this source may be questioned).
If not treated, the person will be 4-5 feet tall (another source:
4’ 3” average). Normal puberty
may or may not occur.
Tests
Tests done include bone age x-ray, growth hormone levels, X-ray of
head, CT, MRI
GHD may be difficult to identify because of HG produces in short
bursts. Also, there is no standard
or reliable means for identifying GHD.
“The determination of GH levels is extremely difficult given
current diagnostic techniques, making universal recommendations for use
problematic.”
“Serial monitoring of spontaneous GH levels over a 24-hour
period is expensive, labor-intensive, and used primarily as a research tool.”
“Due to the inadequacies of these tests, a subnormal growth
velocity often becomes the deciding factor in choosing to initiate GH
therapy.”
“Testing for GHD will occur when other possibilities of short
stature have been ruled out. A child’s growth hormone secretion will be stimulated by
one of several agents such as clonidine and Ldopa.
The release of growth hormone may also be measured over a period of 8-12
hours, since growth hormone secretion varies throughout the day and is greatest
after falling asleep.”
Note: Luke was asleep from 10-60 minutes after he was given
clonidine, which theoretically could cause his GH levels to rise.
He also had had something (very little) to eat that morning, which also
could have raised the levels. Still
he was below the minimum acceptable level.
Ask doctor for a “Stimulation Test Physician Kit” – produced
by Pharmacia and Upjohn.
Treatment of GHD
GHD is not preventable, but is treatable since 1985 with a
synthetic GH (rhGH – recombinant human growth hormone) (from 1958 GH was taken
from the pancreas of cadavers; this greatly limited supply and there were some
cases of contamination). Standard
practice and FDA approved practice for GHD is GH therapy.
Ideal treatment schedules have not yet been developed, but injections may
be daily to 3x a week. There are
usually no side effects if the correct dosage of GH is given.
Treatment with rhGH costs approximately $20,000 annually (cost of
rhGH product only). Treatment of
94% of children with GHD was paid by insurance in one study.
(Annual cost $20k for child weighing 30kg, supposes one single-use vial
of rhGH per day and a dose of 0.3mg/kg/week in 7 daily doses).
RhGH is available in two forms, somatropin and somatrem, both of
which consist of a sequence of 191 amino acides that is identicial to
pituitary-derived GH (aka somatropin). The
only difference with somatrem is that it has an additional amino acid on the
N-terminus of the molecule. Numerous
rhGH products are sold.
Injections can be administered subcutaneous or intramuscular.
Amount and frequency of injections depends on condition being
treated, patient’s weight and height, type and severity of side effects and
the degree to which Gh-regulated proteins or enzymes, such as IGF-I, are
normalized. Treatment may go until
attainment of particular target height or bones are fused.
“Some data indicate that a weekly dose of rhGH divided into
daily injections increases growth rate to a better degree than the same weekly
dose divided into three injections in patients with GH deficiency….Some data
also suggest that evening injection produces hormone and metabolite patterns
that are significantly closer to normal than those achieved with morning
injection.”
“Much data indicate that rhGH should begin as early as
possible.” “Early diagnosis is
extremely important for a growth hormone deficient child.
To obtain the best results, a child must be diagnosed and treated at a
relatively young age. Accurate annual measurements and plotting of a child’s
growth chart allows for identification of growth failure and treatment before
the child’s bones fuse. Once
fusing has taken place, no additional growth is possible.”
There is no alternative treatment for GHD than rhGH and therefore
though self-administered at home, Medicare would cover it (for those covered by
Medicare; may be similar to policies of other insurers).
I count 7 FDA approved rhGH products.
Of those, Biotropin iss blocked in US b/c of patent infringement claim;
Norditropin once was but is not now.
“There should be no specific changes in your child’s mood or
activity on growth hormone therapy.”
General recommendation is for child to visit endocrinologist an
average of every three months.
Currently there are 20,000 US children receiving GHD therapy.
Length of Treatment
Some say that treatment ends when full height is attained or bone
age is over that of a 16 year old boy. UCLA
ped. Endocrinologist and another source: “Even after growth stops, however,
growth hormone must continue to be present (at somewhat lower levels) throughout
life to maintain physical and mental health and well-being.
Tissue repair, healing, cell replacement, organ integrity, bone strength,
brain function, enzyme production, integrity of hair, nails, skin and vital
organs all require the ongoing availability of adequate growth hormone.”
Immediate Results of Therapy
Usually treatment results in growth of 4-6 inches in height the
first year.
“Growth prior to therapy is generally less than 4 or 5 cm per
year and 8 to 10 cm per year during the first year of therapy….Growth may be
between 8 to 12 cm per year following the initial year of growth hormone
therapy. The second and third year
may be closer to 7 cm per year.”
“Growth hormone stimulates the growth of muscles and bones and
helps regulate metabolism. Growth hormone can sharply increase the flow of sugar into
muscle and fat, stimulate protein production in liver and muscle, and slow the
production of fatty tissue. More
prolonged effects of growth hormone—blocking the uptake and use of sugars,
causing blood sugar levels to rise, and increasing the production of fat and fat
levels in the blood—seem to counteract its immediate effects.
Long-Term Results of Therapy
“The majority of children under therapy today reach a normal
adult height or nearly their full growth potential.”
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