A quick guide to the thyroid gland, thyroid hormones and thyroid disorders

Thyroid disorders are pretty common in India. It is estimated that around 1 in 10 Indians suffer from thyroid-related problems. Read to know more about the thyroid gland, its hormones, related disorders, their symptoms, diagnosis, treatment and more.

What is the thyroid gland?

The thyroid gland is a butterfly-shaped structure which is situated at the base of your neck just above the collarbone, in front of your windpipe (trachea). It produces and stores two important hormones – thyroxine (T4) and triiodothyronine (T3). These are collectively called thyroid hormones.

Additionally, the thyroid also produces another hormone called calcitonin, which is essential for regulating calcium levels in the body.

Why are thyroid hormones important?

Thyroid hormones are very critical for the normal functioning of the body. They are involved in –

Metabolism
Digestion
Regulation of body temperature
Brain development
Cognitive functioning

What is thyroid stimulating hormone (TSH)?

Thyroid stimulating hormone or TSH is a hormone produced by your pituitary gland. It controls how the thyroid gland produces thyroid hormones. If there is a decrease in thyroid hormone levels in your blood, the hypothalamus, a part of your brain, stimulates the pituitary gland to produce TSH. The thyroid gland is subsequently stimulated by TSH to produce thyroid hormones.

In hypothyroidism, the levels of thyroid hormones (T3 and T4) are reduced and the TSH level is elevated in the blood. In hyperthyroidism, the TSH levels will be decrease.

What are thyroid diseases?

Thyroid diseases refer to diseases and disorders affecting the thyroid gland. These include:

Hypothyroidism: The thyroid gland is unable to produce adequate thyroid hormones to maintain normal body functions
Hyperthyroidism: Thyroid hormones are produced in excess quantities, causing the metabolism to speed up and leading to multiple problems

What causes thyroid disease?

Causes of hypothyroidism include:

Hashimoto’s thyroiditis
Surgical removal of the thyroid gland
Thyroiditis
Inborn diseases of the thyroid gland
Iodine deficiency
Disease of the pituitary gland or hypothalamus (these are two glands that regulate the production of thyroid hormones)
Some medications such as hyperthyroid medications, amiodarone (anti-arrhythmic), lithium (mood stabiliser), various anti-cancer medications etc.
Side effects of cancer radiotherapy

Causes of hyperthyroidism include:

Grave’s disease
Nodules on your
thyroid gland (toxic nodular goitre)
Thyroiditis
Excess iodine intake
Excess thyroid medication intake
Non-cancerous tumours of the pituitary gland

What are the symptoms of thyroid disease?

Hypothyroidism –

Fatigue
Dry skin and hair
Weight gain
Hair loss
Cold clammy skin
Intolerance to cold temperatures
Menstrual abnormalities
Depression
Disorientation and decreased memory
Fertility problems
Decreased appetite

Hyperthyroidism –

Restlessness
Increased body temperature
Increased sweating
Increased sensitivity
to hot temperatures
Shaking
Anxiety
Brittle nails and hair
Weight loss
Nervousness
Rapid heart rate and palpitations
Bulging of the eyes
Menstrual abnormalities

What is goitre?

Goitre is a neck swelling caused by an enlarged thyroid gland. It is associated with an improperly functioning thyroid gland. Goitre is most commonly caused due to an iodine deficiency. Although most goitres are not cancerous, they can be associated with cancerous changes.

How will thyroid disease impact my life?

The symptoms of thyroid disease such as fatigue, mood changes and weight changes can affect your personal as well as professional life. Once diagnosed, treatment has to be initiated at the earliest and followed up regularly to attain a timely resolution.

How is thyroid disease diagnosed?

Based on your symptoms, if your doctor suspects thyroid disease, you will be asked to take the following blood tests:

Thyroid stimulating hormone (TSH) test
T4 test (measures the level of T4 (thyroxine) in the blood)

T3 test (Measures the level of T3 (triiodothyronine) in the blood) You may also be asked to undergo additional tests to confirm the diagnosis. These include:

Radioactive iodine uptake scan: This detects how much radioactive iodine is taken up by the thyroid gland. It shows how active your thyroid gland is
Ultrasound scan
Fine needle aspiration biopsy (FNAB): This is done if you have nodules on your thyroid gland. Using a fine needle attached to a syringe, a few cells are removed from the nodule and studied under the microscope. This is performed to evaluate if the nodules are cancerous

How do I prepare myself for thyroid blood tests?

You usually do not have to take any special precautions, such as fasting, before thyroid tests. But if you are being advised to take additional tests along with your thyroid hormone profiling, you may have to fast for 8 to 10 hours. Hence, talk to your doctor or pathologist to confirm if you need to fast
It is advisable to take your thyroid hormone supplements, if any, after you have given the blood sample for thyroid hormone profiling. However, it is always better to confirm this with your doctor
Some medicines, such as biotin supplements, can interfere with the results of your test. Hence, it is advisable to avoid biotin for 2 days before you undertake the blood test for thyroid hormone profiling

When should I get my thyroid levels checked?

If you have persisting symptoms of thyroid disease such as sudden weight loss or gain, swelling in the neck (goitre), menstrual irregularities, hair fall, etc., it is ideal to consult a doctor and get your thyroid levels checked.

What is the treatment for thyroid disease?

Depending on the cause of your thyroid disease your treatment options may vary. Generally, for patients with hypothyroidism, medicines that contain thyroid hormones are prescribed. For hyperthyroidism, anti-thyroid hormones, drugs that reduce the production of thyroid hormones, are prescribed. In some cases, thyroid surgery may be required.