Factsheet on Congenital Hypothyroidism

1.      What is Hypothyroidism?

Deficiency of thyroid hormones or defect in thyroid hormone actions is called Hypothyroidism. Thyroid gland situated in the neck produces two hormones; thyroxine (T4) and triiodothyronine (T3). Thyroid hormones play a critical role in growth and development and maintenance of normal body processes. Without sufficient thyroid hormones, both mental and physical growth in children is hampered. In adults, it can affect various systems of the body. In the developed countries the prevalence of hypothyroidism is about 4-5%. According to a recent Indian study done in eight major cities, more than 10% of adults were found to suffer from hypothyroidism.

2.      What is Congenital Hypothyroidism?

Hypothyroidism in an infant means that the baby is not making enough thyroid hormone to grow and develop normally. The word congenital means that the baby was born with the condition. Thus, when there is deficiency of thyroid hormones in new born babies, it leads to a condition called as “Congenital Hypothyroidism”. In new born babies, thyroid hormones are extremely important for brain development and overall growth. In Congenital Hypothyroidism, the baby suffers from mental retardation, and improper growth. If left untreated, the damage becomes irreversible. When diagnosed early and treated adequately, children born with Congenital Hypothyroidism can experience normal physical growth and neurological development.

3.      Congenital Hypothyroidism in India: how common is the condition?

Worldwide Congenital Hypothyroidism affects 1 in 3,800 new born babies. Reports from India state that the situation is much worse with a figure of 1 in 2,640.

4.      What are the key features of Congenital Hypothyroidism?

Most new born babies with Congenital Hypothyroidism appear normal at birth, even if there is complete lack of development of the thyroid gland. This is because a small amount of thyroid hormone (T4) from the mother is transferred to the baby during pregnancy.

It is twice as common in girls as in boys. In Congenital Hypothyroidism, birth weight and length are normal, but head size may be slightly increased. Prolongation of physiologic jaundice may be the earliest sign. Feeding difficulties, especially sluggishness, lack of interest, sleepiness, and choking spells during nursing are often present during 1^st month of life. Respiratory difficulties, due in part to the large tongue may also occur. Affected infants cry little, sleep much, have poor appetites and are generally sluggish. The abdomen is large, and an umbilical hernia is usually present. The temperature is below normal, often less than 35°C, and the skin, particularly that of extremities may be cold and mottles. Swelling of the genitals and extremities may be present. Because symptoms appear gradually, the clinical diagnosis is often delayed.

Approximately 10% of infants with Congenital Hypothyroidism have other associated abnormalities. Cardiac abnormalities are most common, but abnormalities of the nervous system and eye can also be there.

5.      What are the causes of Congenital Hypothyroidism?

Most cases of Congenital Hypothyroidism are not hereditary and result from abnormal development of the thyroid gland. Some cases may be familial due to errors of thyroid hormone synthesis. In many cases deficiency of thyroid hormone is severe and symptoms develop in early weeks of life. In others lesser degree of deficiency occurs and appearance of symptoms may be delayed for months.

6.      Can Congenital Hypothyroidism problem be prevented?

Most cases cannot be prevented. The following are some things that can be done during pregnancy under the doctor’s guidance to reduce the risk:

1.      Mothers should not have radioactive iodine treatment or use iodine as antiseptic.

2.      Mothers should consume enough, but not too much iodine.

Both these precautions should be exercised under the strict guidance of the doctor.

7.      When is the ideal time to screen an infant for Congenital Hypothyroidism?

-          Screening of infants should be performed between two and four days of birth. If this is not possible, testing should be performed before discharge or within seven days of birth.

-          The neonatal screening for Congenital Hypothyroidism was introduced in 1974 by using newborn heel prick filter paper blood sample and it is a universal practice in the developed countries to screen all the new born babies for Congenital Hypothyroidism.

8.      Can Congenital Hypothyroidism be detected earlier than the birth of the child?

-          As Congenital Hypothyroidism is most commonly not a heritable disorder, it is not possible to identify a population of pregnant women who are at high risk for fetal hypothyroidism.

-          Specific pregnancies may be determined to be at risk based on a family history of a previous infant with Congenital Hypothyroidism. Most cases, however, are not familial and are discovered when routine ultrasonography discloses a fetal goiter. In addition, if a pregnant woman with Graves’ disease is treated with antithyroid drugs, the fetus is at risk for hypothyroidism. If the mother has been exposed to radioactive iodine, then the baby has increased risk of Congenital Hypothyroidism.

9.      Is screening test for Congenital Hypothyroidism available in India?

The screening test is a simple test available in many hospitals and laboratories across India. Please consult your doctor for more information on availability of the screening test in your nearest hospital.

10.  If the baby is diagnosed with Congenital Hypothyroidism, is there any treatment available?

-          Once a baby is diagnosed with Congenital Hypothyroidism, he or she is immediately started on thyroid hormone replacement. Levothyroxine given orally is the treatment of choice. Levothyroxine is a synthetic thyroid hormone that is similar to the hormone made by a thyroid gland.

11.  How often is this treatment given and how long should the treatment be continued?

Usually, levothyroxine is given once a day. Most of the children with Congenital Hypothyroidism need to take thyroid hormones for the rest of their lives.

12.  Can the complications be prevented with adequate treatment?

Early diagnosis and adequate treatment from the first weeks of life result in normal growth and intelligence. Delay in diagnosis, failure to correct initial hypothyroidism rapidly, inadequate treatment and poor compliance in first 2-3 years of life result in variable degree of brain damage. Thus, early diagnosis soon after birth and effective treatment can prevent irreversible brain damage.  

13.  What are the side-effects of the treatment?

-          Because thyroxine medicine is simply replacing a normal hormone produced by the body, giving the correct dose everyday should be well tolerated. However, if given too little thyroxine, the baby will develop symptoms of hypothyroidism outlined earlier, and over a long period, may grow more slowly than usual.

-          If the child is given too much levothyroxine, he or she may develop mild diarrhea, may be more restless than usual and other symptoms due to excess thyroid hormones. But, normally, the correct dose for the infants can be calculated so that these adverse effects can be avoided.

References:

·         Desai M. Congenital Hypothyroidism: screening dilemma. Indian Journal of Endocrinology and metabolism 2012;16:S153-5.

·         Great Ormond Street Hospital. Congenital Hypothyroidism. Last reviewed by Great Ormond Street Hospital: December 2010. Downloaded from http://www.gosh.nhs.uk/medical-conditions/search-for-medical-conditions/congenital-hypothyroidism/congenital-hypothyroidism-information/ accessed on 23 Aug, 2013. 

·         Jameson JL,Weetman AP. Disorders of the thyroid gland. In Fauci AS, et al, editors. Harrisions Principles of Internal Medicine. 17^th ed. vol 2; McGrawHill, New Delhi: p. 2224-47.

·         LaFranchi S. Disorders of the thyroid gland. In Kliegman RM, et al, editors. Nelson Textbook of Pediatrics. 18^th ed. vol 2; Saunders Elsevier, New Delhi: p. 2316-32.

·         Osborne B, Hopwood NJ. Congenital Hypothyroidism in infants. Downloaded from http://www.med.umich.edu/pediatrics/division/endo/PedHypothyFinal.pdf accessed on 25th Aug, 2013.

·         Rastogi MV, LaFranchi SH. Congenital Hypothyroidism. Orphanet Journal of Rare Diseases 2010, 5:17. Downloaded from http://www.ojrd.com/content/5/1/17 accessed on 12th Aug, 2013.

·         Scheinberg D. Congenital Hypothyroidism. Downloaded from http://healthlibrary.epnet.com/print.aspx?token=de6453e6-8aa2-4e28-b56c-5e30699d7b3c&ChunkIID=102705 accessed on 25th Aug, 2013.

·         Smith L. Updated AAP guidelines on newborn screening and therapy for Congenital Hypothyroidism. Am Fam Physician. 2007 Aug 1;76(3):439-44.

·         Unnikrishnan AP, et al. Prevalence of hypothyroidism in adults: an epidemiological study in eight cities of India. Indian Journal of Endocrinology and metabolism 2013;17(4):647-52.

·         Unnikrishnan AP, Menon U. Thyroid disorders in India: an epidemiological perspective. Indian Journal of Endocrinology and metabolism 2011;15(suppl. 2):S78-81.

For more information please consult your doctor.

Issued in public Interest by-

GlaxoSmithKline Pharmaceuticals Ltd. Dr. Annie Besant road, Worli, Mumbai, Maharashtra-400 030

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This publication has been issued as a public awareness initiative from GlaxoSmithKline Pharmaceuticals Ltd and is distributed free of cost. Although great effort have been made to ensure that the information contained herein is complete and accurate in every respect, the information may be inaccurate, incomplete or become outdated over a period of time. GlaxoSmithKline Pharmaceuticals Ltd . disclaims any liability for accuracy, completeness or use of the information contained in this publication.

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