What is iodine deficiency?

Iodine deficiency is a shortage of iodine in a person's body. You need the right amount of iodine for your metabolism and for the healthy functioning of your thyroid gland.

Iodine deficiency is the most common cause of thyroid disease and, if serious, can cause permanent brain damage and intellectual disability in babies.

Iodine is a mineral found naturally in seawater and soil. The body needs iodine to make thyroid hormone in the thyroid gland. Thyroid hormone influences metabolism and is essential for the development and function of the brain, nerves and bones.

There is a growing problem in Australia with iodine deficiency, especially among children and pregnant or breastfeeding women. This puts them at risk of thyroid problems and leads to other serious consequences.

If children and unborn babies have too little iodine, there can be problems with normal development including:

• brain damage
• intellectual disability, including the most severe form cretinism
• low IQ
• stunted growth

In women, iodine shortage can cause:

• fertility problems
• problems with pregnancy such as miscarriage, stillbirth and brain and nerve damage to the developing fetus

Find out more here about iodine and recommended iodine daily intake.

What are the symptoms of iodine deficiency?

Many people don’t know they have an iodine deficiency. However, some people who don’t have enough iodine develop a goitre, or enlargement of the thyroid gland in the neck.

Iodine deficiency can also lead to hypothyroidism, (underactive thyroid, where there is too little of the thyroid hormone). This can cause symptoms including:

• constant tiredness
• muscle weakness
• unexpected weight gain
• difficulty learning and remembering
• constipation
• weak, slow heartbeat
• dry skin
• hair loss
• puffy face
• feeling cold

What causes iodine deficiency?

In some parts of Australia, there is too little iodine in the soil, so people living there are at greater risk of iodine deficiency.

To counteract this lack of iodine in the soils and food in Australia, iodine is put in most table salts (called iodised salt). Since 2009, mandatory iodine fortification is used in all breads that are not organic. Eating packaged breads provides enough iodine for many people, but not enough for pregnant and breastfeeding women.

Some people don’t get enough iodine because the foods that contain it, such as seafood, tend to be more expensive. Eating organic bread or specialty salt also mean people are missing out on iodine in their diet.

While anybody can develop iodine deficiency, those most at risk are:

• pregnant women
• breastfeeding mothers
• fetuses (unborn babies)
• newborn babies

How is iodine deficiency diagnosed?

The doctor will do a physical examination and order a urine test or a thyroid stimulating hormone (TSH) blood test. If the results show abnormal levels of TSH, you may have further tests such as an ultrasound to look at the thyroid gland.

In Australia, newborn babies are routinely given a screening blood test known as the “heel prick” that will pick up a low thyroid hormone level. This can be a sign of iodine deficiency or have other causes.

If you have an iodine deficiency, you will probably be referred to a specialist doctor called an endocrinologist.

How is iodine deficiency treated?

It is usually treated through eating more foods containing iodine, using iodised salt and taking iodine supplements.

People with hypothyroidism are usually treated with a synthetic form of the thyroid hormone, which they will need to take for the rest of their lives.

How do you prevent iodine deficiency?

Most people can get enough iodine from eating iodine-rich foods such as seafood. You can use small amounts of iodised salt and eat packaged bread to increase the amount of iodine in your diet.

The National Health and Medical Research Council recommends that all women who plan to get pregnant, are pregnant or are breastfeeding should take an iodine supplement of 150 micrograms a day. Talk to your doctor about this.

Taking too much iodine can also cause thyroid problems, so don't exceed the recommended dose of supplements.

Resources and support

The Thyroid Foundation has a factsheet about iodine supplementation for pregnant and breastfeeding women.