Congenital hypothyroidism
Key points
- Congenital hypothyroidism describes a newborn with decreased (or, very rarely, absent) thyroid hormone production.
- Hypothyroidism in the newborn may result from absence of or abnormal development of the thyroid gland, destruction of the thyroid gland, failure of stimulation of the thyroid by the pituitary, and/or by defective or abnormal synthesis of thyroid hormones.
- Most of the effects of hypothyroidism are easily reversible.
- Very early diagnosis generally results in a good outcome for the infant, in terms of growth and mental capability.
Alternative names
Cretinism
Definition
Congenital hypothyroidism describes a newborn with decreased (or, very rarely, absent) thyroid hormone production.
Causes, incidence, and risk factors
Hypothyroidism in the newborn may result from absence of or abnormal development of the thyroid gland, destruction of the thyroid gland, failure of stimulation of the thyroid by the pituitary, and/or by defective or abnormal synthesis of thyroid hormones.
Incomplete development of the thyroid is the most common defect and occurs at a rate of 1 out of every 3,000 births. Girls are twice as often affected than boys.
Most affected infants have little or no symptoms, because they only have a mild deficiency of thyroid hormone. However, infants that are profoundly hypothyroid often have a distinctive appearance with a puffy-appearing face, a dull look, and a large tongue that protrudes from the mouth, which is usually kept open.
They usually develop this appearance as the disease progresses. They may have dry, brittle hair; low hairline; and jaundice. Feeding is poor and the infant may choke frequently. Constipation is common. Affected children do not cry much, but sleep excessively and are sluggish and inactive. Muscle tone is usually decreased.
If untreated, even mild hypothyroidism can lead to severe mental retardation and growth retardation. Development is delayed early on, often indicated by failure to meet normal milestones.
The appearance of teeth may be delayed. These problems become more severe as the child ages. Growth failure in terms of body length is noted very early.
Symptoms
- floppy infant
- thick, protruding tongue
- poor feeding
- choking episodes
- constipation
- prolonged jaundice
- short stature
Signs and tests
- sutures - separated widely and a large posterior fontanelle
- large fontanelle and posterior fontanelle (soft spots)
- dull-appearing facial features
- dry, brittle hair and low hairline
- short, thick neck
- growth failure
- short extremities
- broad hands with short fingers
Written and revised by
David Cohen, M.D.
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