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U N I T 9
Endocrine System
lesion is clinically suspected. After the cause of short
stature has been determined, treatment can be initiated.
Idiopathic Short Stature.
Idiopathic short stature,
also referred to as normal-variant short stature, is short
stature of undefined cause.
11–13
It has been defined as a
condition in which the height of an individual is more
than 2 standard deviations below the corresponding
mean height for a given age, sex, and population group
without evidence of systemic, endocrine, nutritional, or
chromosomal abnormalities.
10
This definition includes
children with familial short stature and constitutional
delay in growth and puberty. Children with familial
short stature tend to be well proportioned and to have
a height close to the midparental height of their parents.
The midparental height for boys can be calculated by
adding 13 cm (5 inches) to the height of the mother,
adding the father’s height, and dividing the total by two.
For girls, 13 cm (5 inches) is subtracted from the father’s
height, the result is added to the mother’s height, and the
total is divided by two.
9
Ninety-five percent of normal
children are within 8 cm (i.e., ±2 standard deviations) of
the midparental height.
Constitutional delay in growth and puberty
describes
children (particularly boys) who have moderately short
stature, thin build, delayed skeletal and sexual matura-
tion, and absence of other causes of decreased growth.
Catch-up growth
is a term used to describe an abnor-
mally high growth rate that occurs as a child approaches
normal height for age. It also occurs after the initiation
of therapy for GH deficiency and hypothyroidism and
the correction of chronic diseases.
9
Psychosocial Dwarfism.
Psychosocial dwarfisminvolves
a functional hypopituitarism and is seen in some emotion-
ally deprived children. These children usually present with
poor growth, potbelly, and poor eating and drinking hab-
its. Typically, there is a history of disturbed family rela-
tionships in which the child has been severely neglected or
disciplined. Often, the neglect is confined to one child in
the family. Growth hormone function usually returns to
normal after the child is removed from the constraining
environment. The prognosis depends on improvement in
behavior and catch-up growth. Family therapy usually is
indicated, and foster care may be necessary.
Growth Hormone and Insulin-Like Growth Factor
Deficiencies in Children.
There are several forms of
GH deficiency that present in childhood. Children with
idiopathic GH deficiency lack the hypothalamic GHRH
but have adequate somatotropes, whereas children
with pituitary tumors or agenesis of the pituitary lack
somatotropes.
Congenital GH deficiency is associated with a shorter
than normal birth length, followed by a decrease in
growth rate that can be identified by careful measure-
ment during the first year and that becomes obvious by
1 to 2 years of age. Children with classic GH deficiency
have normal intelligence, short stature, obesity with
immature facial features, and some delay in skeletal
maturation (Fig. 32-2). Puberty often is delayed, and
males with the disorder have microphallus (abnormally
small penis), especially if the condition is accompanied
by gonadotropin-releasing hormone (GnRH) deficiency.
In the neonate, GH deficiency can lead to hypoglyce-
mia and seizures; if ACTH deficiency also is present,
the hypoglycemia often is more severe. Acquired GH
deficiency develops in later childhood. It may be caused
by a hypothalamic-pituitary tumor, particularly if it is
accompanied by other pituitary hormone deficiencies.
When short stature is caused by a GH deficiency, GH
replacement therapy is the treatment of choice. Growth
hormone is species specific, and only human GH is effec-
tive in humans. Human GH is now produced by recom-
binant deoxyribonucleic acid (DNA) technology, and is
available in adequate supply. The hormone is adminis-
tered daily by subcutaneous injection during the period
of active growth and can be continued into adulthood.
9
Children with short stature due to Turner syndrome and
chronic renal insufficiency also are treated with GH.
Growth hormone therapy may also be considered for
children with idiopathic short stature.
10
In a rare condition called
Laron-type
dwarfism there
is an extreme resistance to GH due to abnormalities in
the growth hormone receptor.
9,14
Affected persons tend
to be obese and have high levels of GH and low levels
of IGF-1. The condition is seen predominantly in people
of Mediterranean descent, especially Sephardic Jews.
FIGURE 32-2.
Child with growth hormone deficiency. A
5.5-year-old boy (left) with growth hormone deficiency was
significantly shorter than his fraternal twin sister (right),
with the discrepancy beginning early in childhood. Notice
his chubby, immature appearance compared with his sister.
(From Shulman D, Bercu B, volume eds. Atlas of Clinical
Endocrinology, Volume IV: Neuroendocrinology and Pituitary
Disease. Korenman S, series ed. Philadelphia, PA: Current
Medicine; 2000. With kind permission of Springer Science +
Business Media.)
