The thyroid is one of the endocrine glands in the human body, situated in the neck just below the larynx. The gland produces the hormone “thyroxin” which is essential for many functions of the body such as growth, intelligence, temperature control etc. In certain disease conditions, the thyroid gland can either under function (hypothyroidism) or over-function (hyperthyroidism) both of which are unhealthy. In rare cases, the thyroid gland can be absent from birth in some individuals.
Congenital hypothyroidism
Congenital hypothyroidism or reduced thyroxin hormone from birth is one of the important causes of preventable mental retardation. A newborn baby can be deficient of the thyroxin hormone due to various reasons, the commonest being partial or complete absence of the thyroid gland. Congenital hypothyroidism is also common in areas where iodine deficiency is seen in the adult population. Iodine is the prime chemical compound required for the synthesis of thyroxin hormone. Some maternal medications including anti-thyroid drugs may affect the baby’s thyroid by crossing the placental barrier and can result in congenital hypothyroidism.
Clinical evidence of hypothyroidism is usually difficult to detect in the newborn period. Common features of a hypothyroid infant are:
1. large protruding tongue
2. hoarse cry
3. facial puffiness
4. lethargy
5. cold hands and feet
6. floppy muscles
7. mottled skin
8. umbilical hernia
But these classic features are subtle and only develop with time. Other suspicious signs are prolonged yellow discolouration of the baby’s skin (jaundice), constipation and feeding difficulties. Some babies have a large soft fontenelle (soft part of the skull).
Affected babies otherwise appear normal at birth with normal growth parameters. However if the diagnosis is delayed, subsequent growth becomes impaired. Early diagnosis and initiation of thyroxin hormone replacement allows near normal achievement of growth, development and intelligence.
Increased or decreased function of the thyroid gland during pregnancy can have a negative impact on the child’s psychological development resulting in a low IQ score and a decrease in motor skills, attention, language and reading abilities. Hypothyroidism can also result in early pregnancy loss.
Problems in the thyroid gland may appear later in childhood as well. They are called acquired thyroid disorders. The most common symptoms include failure to grow at normal rates, significant weight changes, difficulty in concentration and inattentiveness at school, hyperactivity and unexplained day-time fatigue. Since thyroid disorders can run in families, children who come from families with a history of thyroid diseases are especially at risk and need investigating.
As proper thyroid function is essential for normal growth and development, it is crucial that any child with a thyroid disorder is monitored carefully.
Acquired hypothyroidism
Acquired hypothyroidism (autoimmune thyroiditis) is usually very slow moving which makes diagnosis difficult. Diagnosis normally occurs once the child is symptomatic, at which point the disorder has been with him/her for sometime, may be for months or possibly years. In a child, the bone age test can help in determining the onset of the disorder.
Auto-immune thyroiditis is the commonest cause for acquired hypothyroidism. It results from an abnormal antigen antibody reaction which leads to gradual deterioration of the hormone production by destroying thyroid cells. Auto-immune thyroiditis can be associated with dysfunction of other endocrine glands as well including adrenals, pancreas and parathyroid glands which needs careful evaluation if clinical indications are present.
A child can also acquire hypothyroidism due to endemic iodine deficiency. A goitre in the neck is commonly seen as the gland enlarges in the compensatory process. Exposure to food interfering with thyroid hormone production in the susceptible population can result in frank hypothyroidism.
Initiation of thyroid hormone replacement rapidly normalizes the metabolic derangements in the body and restores normal growth.
Hyperthyroidism
Hyperfunction or over-activity of the thyroid gland also has adverse effects on health by releasing excess Thyroxin (T4 ). We call this condition – Hyperthyroidism. Autoimmune processes resulting from abnormal antigen-antibody reactions involving the thyroid gland are the commonest reasons for this excessive thyroid hormone secretion. Sometimes a child who develops hyperthyroidism might end up in hypothyroidism later on in life due to gradual destruction of the hormone producing cells by auto immune processes. Therefore it is mandatory to monitor affected children closely by frequent assessment of thyroid status.
The onset of hyperthyroidism may be insidious and is well established before presentation to a paediatrician. As in hypothyroidism, deterioration of school performance may be marked, but usually due to poor concentration. Tiredness and behavioural disturbances can be observed. There is marked loss of weight despite enormous appetite. The child might also experience rapid heart beat, increase bowel motions and lack of sleep. Visible and palpable thyroid gland is usually evidence on presentation to the doctor.
Hyperthyroidism, similar to hypothyroidism, can be successfully treated. Treatment is targeted at suppressing the excessive thyroxin secretion. This is achieved with antithyroid drugs, surgery or radio-active iodine. With treatment, thyroid functions normalize within 3-4 weeks.
Thyroid cancer
Thyroid cancer, although rare, is a well recognized entity. The usual presentation is with a palpable nodule in the thyroid gland. Diagnosis requires a biopsy with combined surgical and medical therapy. The outcome of thyroid cancers is generally excellent.
If you are worried that your child may be experiencing thyroid problems, don’t hesitate to discuss your concerns with a doctor. Thyroid disorders at any age require immediate medical care, but the urgency is even greater when it comes to diagnosing and treating thyroid disorders in children.
By taking action as soon as you notice any problem, you would be greatly increasing your child’s long term health. It will allow your child reach his/ her full potential in physical development as well as educational achievement. Non-treatment and delay in commencing treatment would both result in stunting of physical growth and low intelligence.
(The writer is a Consultant Paediatrician) |
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