Hypothyroidism - What is it for

Located in the middle of the neck, the butterfly-shaped thyroid gland is responsible for producing thyroid hormones. These hormones are imperative in maintaining the body's metabolism.

Hypothyroidism refers to underactivity of the thyroid gland. When the thyroid gland is underactive, it produces insufficient thyroid hormone which could cause a "slowing down" of various bodily functions.

Another way the thyroid gland could malfunction is by producing excessive thyroid hormone. This condition is known as hyperthyroidism, learn more about hyperthyroidism here.

Hypothyroidism - Symptoms

The symptoms may differ from individual to individual. At a glance, here are the common symptoms associated with hypothyroidism:

Cold intolerance (you feel cold more easily compared to other people)
Weight gain
Prolong fatigue and weakness
Constipation
Abnormal menses or heavy/prolonged menses
Depression or irritability
Hair loss
Dry, rough skin
Muscle aches or cramps

Occasionally, some patients with hypothyroidism have no symptoms, or symptoms that are subtle enough to go unnoticed.

Think you may have hypothyroidism? Find out how to get diagnosed for hypothyroidism.

Hypothyroidism - How to prevent?

Hypothyroidism - Causes and Risk Factors

The more common causes of hypothyroidism include the following:

Hashimoto’s disease: This "autoimmune" or "self-attacking-self" disease occurs when the body's immune system mistakenly attacks thyroid cells and damages them. Over time, the thyroid gland fails, which leads to hypothyroidism
Radioactive iodine treatment: Often when treating hyperthyroidism with radioactive iodine, a condition associated with excessive thyroid hormone production, hypothyroidism is the goal
Thyroid operation: Previous thyroid surgery can result in hypothyroidism, especially if most of the thyroid gland has been removed
Medication: Some medication such as amiodarone and lithium may cause hypothyroidism
Subacute thyroiditis: Subacute thyroiditis causes a painful inflammation of the thyroid and a period of hyperthyroidism as the damaged cells leak their hormone supply into the bloodstream, but this is followed by a period of hypothyroidism
Congenital hypothyroidism: A baby may be born with an insufficient amount of thyroid tissue or other health problems that do not allow for normal thyroid hormone production

While rare, hypothyroidism can also be caused by problems in the pituitary gland, the “master hormone gland” that controls the thyroid gland.

Hypothyroidism - Diagnosis

Patients are required to undergo blood tests to measure Thyroxine (T4) and Thyroid Stimulating Hormone (TSH) levels. Blood tests with high TSH levels but low T4 levels are indications of hypothyroidism.

This diagram illustrates how the thyroid receptor antibody (TRAb) stimulates the thyroid, causing the overproduction of thyroid hormone (T4)

Hypothyroidism - Treatments

Hypothyroidism is treated with thyroxine replacement which is administered in a small pill. The pill is to be taken daily to boost production of thyroid hormone in the bloodstream to normal levels.

Our doctors will determine the right dosage based on the blood test readings of T4 and TSH levels.

Follow-up blood tests may only need to be done once, annually, subject to your doctor's discretion.

What are the side effects of Thyroxine Replacement?

There are very few side effects and almost no allergic reactions associated with thyroxine replacement.

If you suspect you have hypothyroidism, book a consultation with our doctors who will advise the next course of action.

Hypothyroidism

Hypothyroidism: Overview, Causes, Symptoms, Treatments and More | Singapore General Hospital

Hypothyroidism - What is it for

Hypothyroidism - Symptoms

Hypothyroidism - How to prevent?

Hypothyroidism - Causes and Risk Factors

Hypothyroidism - Diagnosis

Hypothyroidism - Treatments

What are the side effects of Thyroxine Replacement?

Hypothyroidism - Preparing for surgery

Hypothyroidism - Post-surgery care

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Prof Ivy Ng

SingHealth GCEO