AROUND the world, more than 200 million people have problems with their thyroid glands. But over 50% are not aware of this because some forms of the disease may be silent. Although we do not have good figures for Malaysia, there is no reason to believe that the pattern here will be any different.

The thyroid gland is a small, butterfly-shaped organ located at the front of the neck, and it plays a key role in controlling many of the body's functions. The gland makes, stores, and releases thyroid hormones into the blood, regulating metabolism. These hormones are essential for the proper functioning of all our organs, including our heart, musculoskeletal system, and brain. They are important from foetal life to old age; controlling everything - from sexual function to intelligence.

There are two main functional disorders of the thyroid gland - hypothyroidism (due to a poorly functioning thyroid gland) and hyperthyroidism (caused by an overactive thyroid gland). Non-functional disorders (where the thyroid hormone levels are normal) such as simple goitres and nodules will not be discussed here.

Hypothyroidism

Hypothyroidism due to a poorly functioning thyroid gland is a very common thyroid disorder. This under-production of the hormones (T3 and T4) slows down the body's metabolism, often leaving patients feeling cold, tired and depressed. Patients are also likely to notice they have gained weight despite eating sensibly and may have increased blood pressure and cholesterol levels.

Causes

1. A lack of iodine in the body. Iodine is necessary for the production of thyroid hormones, and iodine deficiency due to inadequate intake is a leading cause of congenital hypothyroidism worldwide. Iodine deficiency also leads to an enlargement of the thyroid gland (goitre). Fortunately this is not so common in Malaysia.
2. Babies can be born without a thyroid gland, or with one that is not properly functioning (congenital hypothyroidism).
3. Autoimmune thyroiditis, where the body's own defence system (antibodies) attacks the thyroid gland, is the major cause of acquired hypothyroidism.
4. Surgical removal of the thyroid gland or treatment with radioactive iodine, often for hyperthyroidism, can also lead to hypothyroidism.
5. Some medicines may cause hypothyroidism. These medicines include amiodarone, lithium, interferon alpha and interleukin-2.

Risk factors

There are certain people who are more at risk than others:

• Females, especially those who are pregnant, during the immediate post-delivery period and after the menopause
• Those with a family history of autoimmune thyroiditis or other immune diseases such as type 1 diabetes
• Those aged over 50
• Patients who have undergone thyroid surgery
• Those with Down's or Turner's syndrome
• Patients treated with radioactive iodine
• People with exposure of the neck to X-ray or radiation treatments
• In addition, Caucasians and Asians are at greater risk than other populations

Symptoms of hypothyroidism may vary from person to person and are non-specific. Because of this, the correct diagnosis can easily be missed.

Key symptoms include:

• Fatigue/drowsiness
• Cold intolerance
• Poor memory
• Unexplained weight gain
• Depression
• A slow heart beat (bradycardia)
• Constipation
• Abnormal menstrual periods and/or fertility problems
• Joint or muscle pains
• Thin and brittle hair, increased hair loss, and nails that crack easily
• Dry, flaky, pale skin
• Puffy face, hands, and feet
• Decreased libido

Consequences

The physical symptoms of hypothyroidism are unpleasant and can affect the sufferer's self-esteem, work, and home and family life. However, hypothyroidism does not just diminish a patient's quality of life. Left untreated, it can cause more serious complications such as high blood pressure and elevated cholesterol levels, causing coronary heart disease, heart failure, infertility, and Alzheimer's disease (increased risk in females). Body functions can slow down so much that patients may slip into a life-threatening coma.

Treatment

Treatment for hypothyroidism is simply replacing the thyroid hormones that the thyroid gland normally makes. Levothyroxine or l-thyroxine (synthetically produced thyroid hormone) is the treatment of choice for patients. Patients will need to take medication for the rest of their lives as there is no cure for the condition, but once on treatment, they will be able to lead normal lives.

Case study

A month after 28-year-old Madam Lee gave birth to her first child, she began to gain weight rapidly. At the same time she experienced extreme tiredness and body aches. Her family doctor attributed the lethargy to the stress of looking after a newborn baby, and her weight gain to the traditional Chinese postnatal diet her mother was feeding her.

Soon after, she complained of breathlessness on climbing stairs and at this point she was screened for thyroid disease. She was discovered to be severely hypothyroid due to postpartum thyroiditis. This is a condition which comes on within six months of delivery due to the body's own antibodies damaging the thyroid gland. Thirty percent of such cases are permanent, and indeed Madam Lee eventually became permanently hypothyroid. However, with daily replacement thyroid hormone therapy she was able to lead a normal life and also have a second child.