Hypothyroidism is a condition where the thyroid gland produces too little thyroxine for the body’s needs. It is also known as an underactive thyroid.

• Hypo - means “under -“
• Hyper - means “over -“

Causes

• Auto immune thyroid disease
• Radioactive iodine or surgery to correct hyperthyroidism or cancer
• Overtreatment of hyperthyroidism with antithyroid drugs
• Some medicines, eg lithium
• Some health foods, eg kelp

Common Symptoms

A slowing down of mental and physical processes of the whole body, such as

• fatigue and tiredness
• sensitivity to the cold
• physical and mental slowness
• dry skin and hair
• low mood or depression
• fertility problems

Diagnosis

• By a physical examination and blood tests
• A high thyroid stimulating hormone (TSH) level with a low thyroxine (T4) level indicate hypothyroidism
• A slightly raised TSH with a normal T4 is called subclinical hypothyroidism
• Subclinical hypothyroidism can develop into clinical or overt hypothyroidism

Treatment

• Levothyroxine tablets (a synthetic version of thyroxine) taken daily, for life
• Tell your doctor if you are taking any other medicines or special foods as some can interfere with levothyroxine absorption
• If you are pregnant or planning a baby, tell your doctor as soon as possible. You will probably need to increase your levothyroxine dose in the first three months.

Follow-up

Blood tests are carried out

• approximately every eight weeks after the start of therapy or after a dose change until the correct dose of levothyroxine is established (i.e. the serum TSH is within the normal reference range)
• once a year thereafter (except in special circumstances such as pregnancy when more frequent testing is required)

It is well recognised that thyroid problem often run in families and if family members are unwell they should be encouraged to discuss with their own GP whether thyroid testing is warranted.

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