HYPERTHYROIDISM - The Overactive Thyroid

Hyperthyroidism occurs when the thyroid gland produces excessive amounts of thyroid hormones into the blood stream. 

Common symptoms include:

• Feeling hot and excessive sweating
• Tremors
• Palpitations
• Feeling of anxiety
• Increased appetite but loss of weight
• Hair loss
• Brittle nails
• Hyperactivity
• Swelling in the front of the neck (an enlarged thyroid gland is called a goitre)
• Eye problems: protruding eyes, watery eyes, visual disturbances, "bags" under the eyes.

Causes of Hyperthyroidism:

Graves Disease:
This is an autoimmune condition and is the most common cause of hyperthyroidism.  It arises when the body's immune system mistakes normal thyroid tissue for foreign invaders, and starts attacking it. 

Thyroid Nodules:
Lumps sometimes develop in the thyroid gland, and these lumps occasional become hyperactive, producing excessive amounts of thyroid hormone.

Excessive Amounts of Thyroid Hormone Replacement Therapy:
If one mistakenly takes too much thyroid hormone replacement medication (to treat hypothyroidism), the reverse may occur (hyperthyroidism).

Too Much Dietary Iodine:
A rare cause of hyperthyroidism.

Diagnosis of Hyperthyroidism:

Blood tests showing elevated thyroid hormone levels will confirm the diagnosis of hyperthyroidism.  There will also be a correspondingly low level of TSH (see earlier explanation regarding this negative feedback relationship).

Sometimes, your doctor may order a radioactive iodine or technetium scan to obtain more information about the cause of your hyperthyroidism, as this may affect the type of treatment.

Treatment of Hyperthyroidism:

No treatment is perfect, and you will need to discuss the treatment options most suitable for you with your doctor.  There are 3 forms of treatment for hyperthyroidism caused by Grave's disease.

(i) Drugs:

There are 2 antithyroid drugs used in the treatment of hyperthyroidism.  They are: carbimazole (more commonly used), and propylthiouracil.

In general, higher doses are used initially and then are subsequently reduced in stages according to your response to treatment.  This will mean regular visits to your doctor and regular blood tests.  In general, symptoms start to improve after about 10 to 14 days of therapy.

Length of treatment may vary, but is commonly up till about 18 months.  At the end of this period, you will be assessed by your doctor to see if you may stop your medication (more blood tests will be done to assess your risk of recurrence).  After stopping medication, you will continue to be monitored for recurrence of hyperthyroidism.  If your symptoms do recur,  your doctor may offer you a second course of treatment with anti-thyroid drugs, or may discuss other treatment options with you.

What you should know about Anti-thyroid drugs:

In general, very few experience any side effects.  The main concern is a very rare side effect in which the bone marrow is suppressed, causing neutropenia and agranulocytosis, which may occur at any time during treatment.  Should you develop a sudden high fever with a severe sore throat, see your doctor immediately and tell him that you are on anti-thyroid medication.  If a blood count confirms low white blood cell counts, the drug must be stopped immediately.

(ii) Radioactive Iodine:

Radioactive iodine is traditionally reserved for older patients and those who have completed having children.  It is administered orally, and acts by destroying the thyroid cells which produce the thyroid hormones.  Before you receive the dose of radioactive iodine, you will be given a consent form to sign, and will receive instructions about avoiding crowded areas and close contact with other people (especially children) for a period of a few days after therapy.

You will be asked to return to see your doctor on a regular basis to assess your thyroid function.  The major side effect of radioiodine is the development of permanent hypothyroidism, requiring replacement therapy with thyroid hormones. Replacement therapy in hypothyroidism is generally deemed much better than anti-thyroid therapy (in hyperthyroidism), because the gland is dormant.  This means less need for frequent monitoring of hormone levels, unlike in the treatment of hyperthyroidism, in which hormone levels may fluctuate ever so often.

(iii) Surgery:

Surgical removal of the thyroid gland is a treatment option for some patients.  In experienced hands, results of surgery are generally good.  However, your surgeon will inform you about some of the risks to consider regarding surgery:

• Small scar over the neck

• Small risk of damage to the parathyroid glands (which lie just behind the thyroid).

• Small risk of damage to the nerves supplying the voice box.

• Risk that you may not be euthyroid following surgery (that is, you may eventually become either hypothyroid or hyperthyroid)

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