The thyroid is a gland in the lower neck. It makes hormones that regulate growth, brain development, and metabolism. Hypothyroidism]]> is a low or absent production of these hormones. Congenital means the conditions is present since birth.
The Thyroid Gland
If this condition is not treated it can cause damage to the brain. This can lead to ]]>mental retardation]]> and abnormal growth.
Causes and Risks
In most cases, the cause is unknown.
The most common known cause is abnormal development of the thyroid gland. A small percentage of cases are inherited.
Other causes may include:
- Medication during pregnancy, such as radioactive iodine therapy
- Maternal autoimmune disease
- Too much iodine during pregnancy
- Inborn error of metabolism
Some babies are born early (before 40 weeks). This may cause a temporary shortage in the thyroid hormones.
Symptoms or signs take time to develop. The symptoms of Congenital hypothyroidism may include the following:
- Puffy face
- Coarse facial features
- Dull look
- Thick protruding tongue
- Poor feeding
- Choking episodes
- Constipation]]> or reduced stooling
- ]]>Jaundice prolonged]]>
- Short stature
- Swollen, protuberant belly button
- Decreased activity
- Sleeps a lot
- Rarely cries or hoarse cry
- Dry brittle hair; low hairline
- Poor muscle tone
- Cool and pale skin
- Goiter (enlarged thyroid)
- Birth defects (eg, heart valve abnormality)
- Poor weight gain due to poor appetite
- Poor growth
- Difficult breathing
- Slow pulse
- Low temperature
- Swollen hands, feet and genitals
At birth, most infants are screened for this condition. Tests may include the following:
- Measurement of free (unbound) thyroxine (T4) levels in the blood
- Measurement of thyroid stimulating hormone (TSH) in the blood
- Thyroid scan (technetium)
- Nuclear imaging (scintigraphy) may help determine the cause of congenital hypothyroidism, which can guide treatment and prognosis
The outcome is best if the condition is caught early. It is important to start treatment before the brain and nervous system are fully developed. If treatment is given early, it could prevent damage.
Left untreated, the condition can lead mental and growth retardation.
Hormone replacement therapy is often done with the hormone thyroxine, given in one of the following forms:
The tablets should be given at least 30 minutes before a meal or feeding.
Once medication starts, the levels of thyroid hormones are checked often. This will help to keep the values within normal range. If values are kept within a normal range, there are no side effects or complications.
Genetics Home Reference
Med Help International
Canadian Task Force on Preventive Health
Thyroid Foundation of Canada
Bongers-Schokking JJ, Koot HM, Wiersma D. Influence of timing and dose of thyroid hormone replacement on the development in infants with congenital hypothyroidism. J Ped . 2000;136:292-297.
Castanet M, Polak M, Leger J. Familial forms of thyroid dysgenesis. Endocr Dev . 2007;10:15-28.
Congenital hypothyroidism. National Institute of Health website. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/001193.htm . Accessed September 12, 2005.
Congenital hypothyroidism. Thyroid Foundation of America website. Available at: http://www.tsh.org/disorders/pregnancy/newborns.html . Accessed September 12, 2005.
Congenital hypothyroidism. US National Library of Medicine website. Available at: http://ghr.nlm.hig.gov/condition=congenitalhypothyroidism . Accessed September 12, 2005.
Gruters A, Krude H, Biebermann H. Molecular genetic defects in congenital hypothyroidism. Europ J Endocr . 2004;151:39-44.
LeFranchi sH, Austin J: How should we be treating children with congenital hypothyroidism. J Pediatr Endocrinol Metab . 2007;20:559-78.
Update of newborn screening and therapy for congenital hypothyroidism. American Academy of Pediatrics. Pediatrics . 2006;117:2290-2303.
Last reviewed January 2009 by ]]>Rosalyn Carson-DeW¹itt, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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