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Fifth stage
Pediatric
Lec-10
د.ندى العلي
11/4/2016
Hypothyroidism
Few diseases affect multiple systems so severely as hypothyroidism yet are associated with
so many nonspecific symptoms and signs. Hypothyroidism can occur at any age
Its clinical manifestation during infancy differs markedly from that of childhood and
adolescence; for this reason, we must distinguish between congenital and juvenile-acquired
hypothyroidism.
ETIOLOGY
In most instances the causes of hypothyroidism differ during infancy and childhood
children with congenital hypothyroidism usually have either familial goitrous
hypothyroidism (dyshormonogenesis)9 or thyroid dysgenesis with an ectopic thyroid
gland located somewhere between the foramen cecum of the tongue and the
anterior mediastinum
In most cases of permanent congenital hypothyroidism, the cause is unknown. Several
inborn errors of thyroid hormone synthesis are inherited as autosomal recessive traits
and usually manifest with thyromegaly on physical examination
The most common cause of hypothyroidism in children beyond the perinatal period is
goitrous or nongoitrous, autoimmune (chronic lymphocytic, Hashimoto's) thyroiditis
HISTORY AND PHYSICAL EXAMINATION
Because hypothyroidism can affect most organ systems to varying degrees, it is very
important that the clinician consider the diagnosis when the patient has many
nonspecific or multisystemic complaints
Congenital Hypothyroidism
Facial edema
Large posterior fontanelle (>0.5 cm)
Rectal temperature below 95° F (35° C)
Decreased stooling (less than one stool per day)
Prolonged hyperbilirubinemia (bilirubin above 10 mg/dl after 3 days of age)
Respiratory distress in a term infant
Umbilical hernia
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Birth weight above 4000 g
Macroglossia
Bradycardia (pulse below 100 beats/min)
Feeding problems and lethargy
Cutaneous mottling, vasomotor instability
Hoarse cry
Hirsute forehead
Increased skin pigmentation
Physical and mental lazyness
Pale, gray, cool, mottled, thickened, coarse skin
Constipation
Coarse, dry brittle hair
Juvenile Hypothyroidism
Growth retardation (below 4 cm/yr)
Delayed bone maturation
Delayed dental development and tooth eruption
Onset of puberty: usually delayed; rarely precocious
Myopathy and muscular hypertrophy
Menstrual disorders
Galactorrhea
LABORATORY DATA
An elevation of the serum TSH value is the single most sensitive test for primary
hypothyroidism (thyroid gland failure)
combination of a low serum thyroxine (T
4
) value and an elevated TSH is diagnostic of
primary hypothyroidism, either permanent or transient, at any age, including term
and preterm infant
thyroid antibody determinations can be very helpful in finding the cause of infantile or
juvenile-acquired hypothyroidism
A bone age determination consistent with that of a normal newborn would suggest
recently acquired, mild congenital hypothyroidism,
The absence of ossification centers at the knee in addition to the presence of only the
two ossification centers in the foot indicates that the fetus was affected by
hypothyroidism during the third trimester of pregnancy.
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THERAPY
The treatment of choice for hypothyroidism in infancy and childhood is the daily
administration of oral L-thyroxine
PROGNOSIS
Infants who were treated adequately for congenital hypothyroidism since the first
month of age have an excellent prognosis for normal intellectual function and linear
growth. However, delays in diagnosis and in the institution of adequate therapy after
3 months of age usually are associated with an increased risk of mental retardation
no permanent intellectual impairment is found among patients who have juvenile
hypothyroidism. Adolescents who have chronic hypothyroidism and severe growth
retardation may never achieve their full growth potential.