Hong Kong Children's Hospital

Genetics and Genomics Clinic

Department of Clinical Genetics

Newborn Screening Programme

Congenital Hypothyroidism

Thyroid Gland

The thyroid gland is one of the major endocrine organs in our body. It secretes a hormone called thyroxine, which is vital for our body metabolism, and is required for growth and mental development.

Causes

1. Absence or underdevelopment of thyroid gland
2. Thyroid gland is not in the right position
3. Impaired thyroxine production from the thyroid gland

Symptoms

No obvious early symptoms until months or years later. Thyroxine is crucial for normal mental development in the first two years of life. If undiagnosed and untreated, short stature and irreversible developmental delay will be resulted.

Blood Testing

The Genetic Screening Clinic of Department of Clinical Genetics, Hospital Authority provides newborn screening for all babies born in public hospitals.

The first screening test uses baby's umbilical cord blood for thyroid function testing. Baby might be required to have re-testing to confirm the thyroid function if the screening result is abnormal. For those with confirmed congenital hypothyroidism, early management and follow-up can then be provided.

Treatment

• Affected baby might require lifelong treatment
• Daily thyroxine supplement
• Regular follow-up

With early treatment, good drug compliance and regular follow-up, baby's growth and mental development will not be affected.

Common Questions & Answers

1. What are the main causes of Congenital Hypothyroidism?
   There are 3 main causes:
   1. Asbsence or underdevelopment of thyroid gland
   2. Thyroid gland is not in the right position
   3. Impaired thyroxine production from the thyroid gland

2. Is Congenital Hypothyroidism a genetic problem?
   It is now evident that genetic cause is contributable to Congenital Hypothyroidism. More research is, however, necessary to substantiate the risk to the offspring.

3. How long does the baby need to take medications if the baby has Congenital Hypothyroidism?
   The duration of treatment depends on the cause of Congenital Hypothyroidism and the baby's condition. Diseased babies need to follow doctor's instruction and some might need to take lifelong medication.

4. Is Congenital Hypothyroidism curable?
   Congenital hypothyroidism might not be curable but is treatable. As long as your baby follows doctor's instruction in taking medication and having regular follow up, your baby's growth and mental development will not be affected.

5. After the raised Thyroid Stimulating Hormone (TSH) has become normal, does it mean the thyroid is functioning properly? Would TSH become abnormal again?
   Generally, it is unusual for TSH to raise again after becoming normal. You may consult your family doctor or paediatrician if you have worry about the baby's result and condition.

6. Is raised Thyroid Stimulating Hormone (TSH) related to any improper food consumption of mother during pregnancy?
   Apart from poor adherence to anti-thyroid drugs as prescribed by doctor, raised TSH is seldomly related to mother's dietary habits during pregnancy.

7. Why is there stress when baby is delivered by Caesarean Section?
   Baby is usually born with stress, whether through normal delivery or by caesarean section. There are many factors, such as the process of labour and cold external environment, which may affect the TSH level.

*This pamphlet does not cover all the questions. You may consult your family doctor or paediatrician if you have further enquiries.

For further enquires, you may contact us.
Genetic Screening Clinic, Department of Clinical Genetics
Address: Specialist Outpatient Clinic, 1/F, Tower B, Hong Kong Children's Hospital, 1 Shing Cheong Road, Kowloon Bay, Kowloon, Hong Kong
Office Tel: 5741 4280

DCG-GSC-CHT
June 2024