Neonatal hypothyroidism

• Alternative Names

  Cretinism; Congenital hypothyroidism; Hypothyroidism - infants

• Causes, incidence, and risk factors

  Hypothyroidism in the newborn may be caused by:

  • A missing or abnormally developed thyroid gland
  • Pituitary gland's failure to stimulate the thyroid
  • Defective or abnormal formation of thyroid hormones

  Incomplete development of the thyroid is the most common defect and occurs in about 1 out of every 3,000 births. Girls are affected twice as often than boys.

• Symptoms

  Most affected infants have few or no symptoms, because they only have a mild decrease in thyroid hormone production. However, infants with severe hypothyroidism often have a distinctive appearance. Symptoms may include:

  • Puffy-appearing face
  • Dull look
  • Thick, protruding tongue

  This appearance usually develops as the disease gets worse. The child may also have:

  • Dry, brittle hair
  • Low hairline
  • Jaundice
  • Poor feeding
  • Choking episodes
  • Lack of muscle tone (floppy infant)
  • Constipation
  • Sleepiness
  • Sluggishness
  • Short stature
• Signs and tests

  A physical exam may reveal:

  • Abnormally large fontanelles (soft spots of the skull)
  • Broad hands with short fingers
  • Decreased muscle tone
  • Growth failure
  • Hoarse-sounding cry or voice
  • Short arms and legs
  • Widely separated skull bones

  Blood tests will be done to check thyroid function. Other tests that may be done include:

  • Thyroid scan
  • X-ray of the long bones
• Treatment

  Early diagnosis is very important. Most of the effects of hypothyroidism are easily reversible.

  Replacement therapy with thyroxine is the standard treatment of hypothyroidism. Once medication starts, thyroid blood tests are regularly done to make sure levels are within a normal range.

• Expectations (prognosis)

  Very early diagnosis generally results in a good outcome. Newborns diagnosed and treated in the first month or so generally develop normal intelligence.

  Untreated, mild hypothyroidism can lead to severe mental retardation and growth retardation. Critical development of the nervous system takes place in the first few months after birth. Thyroid hormone deficiency may cause irreversible damage.

• Complications
  • Mental retardation
  • Growth retardation
  • Heart problems
• Calling your health care provider

  Call your health care provider if:

  • You feel your infant shows signs or symptoms of hypothyroidism
  • You are pregnant and have been exposed to antithyroid drugs or procedures
• Prevention

  If a pregnant women takes radioactive iodine for thyroid cancer, the thyroid gland may be destroyed in the developing fetus. Infants whose mothers have taken such medicines should be observed carefully after birth for signs of hypothyroidism.

  Most states require a routine screening test to check all newborns for hypothyroidism. See also: Newborn screening tests

• References

  Harris KB, Pass KA. Increase in congenital hypothyroidism in New York State and in the United States. Mol Genet Metab. 2007; 91(3):268-277.

Review Date: 5/12/2009

Reviewed By: Robert Cooper, MD, Endocinology Specialist and Chief of Medicine, Holyoke Medical Center, Assistant Professor of Medicine, Tufts University School of Medicine, Boston MA. Review provided by VeriMed Healthcare Network. Also reviewed by Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Previously reviewed by Alan Greene, MD, FAAP, Department of Pediatrics, Stanford University School of Medicine, Lucile Packard Children's Hospital; Chief Medical Officer, A.D.A.M., Inc.