“Hypo” means low or under what is normal, whereas “hyper” means high or above what is normal. So hypothyroidism means the thyroid is underactive and hyperthyroidism means the thyroid is overactive.

In areas of iodine sufficiency, the most common cause of hypothyroidism is Hashimoto’s thyroiditis - an autoimmune disease that causes the immune system to damage or destroy the thyroid gland. Other causes include;

• Surgical removal of the thyroid due to cancer or another disorder
• A birth defect whereby a baby is born without a properly functioning thyroid gland
• Viral or bacterial infections - these can temporarily depress or stop hormone production in the thyroid. Sometimes this can be permanent
• Medications - some medications can induce temporary hypothyroidism (such as lithium, amiodarone)
• Iodine deficiency - a diet severely deficient in iodine can lead to hypothyroidism

Yes, hypothyroidism resulting from the autoimmune disease Hashimoto’s thyroiditis does run in families. Additionally, a family history of autoimmune diseases, including rheumatoid arthritis (chronic inflammation of the joints in the hands and feet), pernicious anaemia (low red blood cells), type 1 diabetes, lupus or other autoimmune diseases, increases the risk of hypothyroidism in offspring.

Unexplained weight gain or an inability to lose weight, usually despite a decrease in appetite, may be a symptom of hypothyroidism. This is because hypothyroidism causes your metabolism to slow down. Be sure to talk to your doctor or pharmacist if you are concerned about your weight.

Some hypothyroidism causes are temporary but not all patients can be cured.

Eating certain foods such as soybean flour, soybean infant formula, cotton seed, walnuts and dietary fiber may decrease absorption of levothyroxine. You may require a change in the dose. How to take SYNTHROID^®:

• Exactly as your doctor tells you.
• Take your dose once per day at the same time every day.
• You should take your dose on an empty stomach, 30 minutes to 1 hour before breakfast.
• Food and drink can affect how your body absorbs SYNTHROID®. For this reason, if you do take your dose with food or drink, be sure to take it this way each time. You must be consistent with how you take your dose.
• Swallow tablet whole with a full glass of water.
• If you are using other medicines, your healthcare professional may recommend that you take SYNTHROID^® 4 hours before or 4 hours after these other medicines.

Serious Warnings and Precautions
Thyroid hormones, including SYNTHROID^®, either alone or with other medicines, should not be used to treat obesity or for weight loss. These medicines can cause serious or life-threatening side effects.

• Exactly as your doctor tells you.
• Take your dose once per day at the same time every day.
• You should take your dose on an empty stomach, 30 minutes to 1 hour before breakfast.
• Food and drink can affect how your body absorbs SYNTHROID®. For this reason, if you do take your dose with food or drink, be sure to take it this way each time. You must be consistent with how you take your dose.
• Swallow tablet whole with a full glass of water.
• If you are using other medicines, your healthcare professional may recommend that you take SYNTHROID^® 4 hours before or 4 hours after these other medicines.

To help avoid side effects and ensure proper use, talk to your healthcare professional before you take SYNTHROID^®. Talk about any health conditions or problems you may have, including if you are pregnant or plan to become pregnant. This is because your dose will likely need to be increased.