Iodine deficiency is not a problem in Singapore,¹ since salt for daily use is fortified with iodine, and iodine-rich foods (such as seafood, eggs, milk and dairy products) are widely available. Most people should be able to get all the iodine they need by eating a variety of foods. People who follow a vegan diet and women who are pregnant may be at risk for low iodine. In such situations, taking iodine-fortified foods and iodine supplements is useful for optimising iodine levels.² 

In countries where people consume enough iodine, there is no specific way to prevent thyroid problems.^1,3 Radiation increases the risk for thyroid cancer, but this affects a small group of people who are exposed to radiation due to their occupation or medical treatment.¹ Early diagnosis and treatment of thyroid problems in people with symptoms or risk factors is the best way for preventing the condition from getting worse.³ 

Goitrogen are substances that block iodine uptake in the thyroid gland and interfere with thyroid hormone production.⁴ They are naturally found in soy and cruciferous vegetables, such as cabbage, turnip, broccoli and cauliflower.^4,5 Boiling, steaming and stir-frying cruciferous vegetables lowers their iodine-blocking effects.⁶ Goitrogens do not affect thyroid function in people who get enough iodine, so consuming appropriate amounts of soy and cruciferous vegetables should not be a concern.² 

Soy foods interfere with the body’s ability to absorb thyroid hormone medication making it less effective for treating hypothyroidism. A higher dose may be needed to maintain normal thyroid hormone levels. There is no need for hypothyroid patients to completely eliminate soy from their diet.⁷ As with any other foods that may affect absorption, patients are advised to take their thyroid hormone medication ~1 hour before eating, or to wait at least 4 hours after eating to take their medication. If you are taking soy supplements regularly, tell your doctor so that your treatment dose can be adjusted if necessary.⁸

Some antithyroid medications are safer for pregnancy than others. Overall, the risk of antithyroid medications causing serious birth defects is extremely low. To avoid complications, hyperthyroid patients who desire pregnancy should plan their pregnancy and discuss with their doctor. Generally, the dose of the antithyroid medication will be kept as low as possible throughout pregnancy.⁹
It is essential that the pregnant woman have her thyroid levels monitored regularly.¹⁰

Lifelong thyroid hormone replacement therapy for hypothyroidism is usually required, particularly if the condition is caused by Hashimoto’s thyroiditis, radioactive iodine therapy, or thyroid removal surgery.¹¹ Symptoms of hypothyroidism are likely to return if treatment is stopped abruptly.¹² It may be possible for some people with a mild form of hypothyroidism – known as subclinical hypothyroidism ‒ to stop thyroid hormone replacement therapy after some time.¹³ If you are thinking of stopping treatment, discuss with your doctor whether this is a safe option for you. Rather than stopping your thyroid medication completely, ask your doctor to lower your dose. If your TSH level goes up, you’ll know that you need to continue treatment!³