Also known as: Underactive Thyroid

What is it?

Hypothyroidism develops when the thyroid gland doesn’t produce enough thyroid hormone. Too little hormone slows down all the chemical reactions in the body, leading to life-threatening complications.

Who gets it?

Hypothyroidism can occur at any age. In the pediatric and adolescent age group it may occur

Congenital hypothyroidism occurs due to abnormality of the thyroid gland from the time of birth. This occurs if the gland is absent (agenesis), not well formed (dysgenesis), present at the wrong place (ectopic gland) or if the gland is not functioning normally due to absence of certain hormones required for formation of the thyroid hormone.

Since thyroid hormone is very important for the development of the brain in the first 3 years of life, if congenital hypothyroidism is not diagnosed, it can result in mental retardation. The symptoms manifest at a late stage and a clinical diagnosis is made only in 10% patients even in the hands of the best clinician. Hence routine screening is very important for early diagnosis and prevention of mental retardation.

Screening for congenital hypothyroidism can be done by taking only a drop of blood from the heel on a filter paper. This facility is now available in a number of Centers in India. If this facility is not available thyroid functions can be checked in venous blood.

How to manage congenital hypothyroidism?

If the thyroid screen result is abnormal, venous blood would be required to confirm the test results. Thyroid scan may need to be done in most babies and an X-Ray of the knees/wrist and hand may be done. The baby is started on replacement therapy with thyroxine, which is available in the form of a tablet only.

The thyroid functions need to be checked periodically in babies who are on replacement therapy so that appropriate adjustments can be made in the dose of thyroxine.

ACQUIRED HYPOTHYROIDISM

Hypothyroidism is one of the most common chronic diseases As many as two of every three people with hypothyroidism may not know they have the disease. The condition can develop in anyone, though hypothyroidism tends to run in families. It tends to occur more often in adolescents, especially females, although it affects both sexes and can occur at any age

What causes it?

Hypothyroidism is most often the result of Hashimoto's disease, also known as chronic thyroiditis (inflammation of the thyroid gland). In this disease, the immune system fails to recognize that the thyroid gland is part of the body's own tissue and invades it as if it were a foreign body. The invasion by the immune system impairs thyroid function and sometimes destroys the gland. Thyroid antibodies can be checked to confirm a diagnosis of Hashimoto’s disease.
Other causes of acquired hypothyroidism include radiation, surgery, viruses and bacteria, certain medications, pituitary gland malfunction, diet, and environmental contaminants.

What are the symptoms?

Deficiency of this hormone leads to slowing of the metabolism. This leads to tiredness, lethargy, excessive weight gain, constipation, cold intolerance, dry skin, slow growth inability to concentrate, and deterioration in school performance. In older girls periods may become irregular. Some patients may present only with an enlarged thyroid gland (goiter) or short stature. A large number of patients do not present with any symptoms till the hypothyroidism is severe and prolonged.

How is it diagnosed?

Hypothyroidism is diagnosed by testing the patient’s blood to measure the level of both thyroid hormones and the pituitary’s thyroid-stimulating hormone (TSH). Thyroid antibodies, and occasionally a thyroid ultrasound or nuclear scan may also be used to confirm the diagnosis.

What is the treatment?

Patients diagnosed with hypothyroidism are prescribed a synthetic thyroid hormone tablet that needs to be taken once daily, preferably half an hour before breakfast. It may take several months to determine the correct dosage, however patients usually start to feel better within 48 hours.