Iodine

Overview

Iodine is a mineral found in some foods that your body needs to make thyroid hormones. These hormones help control your metabolism – how your body uses energy – as well as your growth, heart rate, and body temperature. Not getting enough iodine can lead to problems like a swollen thyroid gland (goitre) and an underactive thyroid.

Iodine deficiency is common in parts of the world where the soil has low iodine levels and there is no routine iodised salt programme. In many countries, it is less common because of iodised salt use, but it can still occur, especially in pregnant women and people who follow strict diets.

Anyone can develop iodine deficiency, but it is more likely to affect pregnant women, breastfed infants, young children, and people who do not eat fish, dairy, or iodised salt. It can also affect people living in regions with iodine-poor soil.

Symptoms

Common symptoms

• Feeling tired and sluggish
• Unexplained weight gain
• Dry skin and hair
• Hair loss
• Feeling cold more easily than usual
• Constipation
• Swelling at the front of the neck (goitre)
• Weakness or muscle aches

Symptoms in children

• Slow growth and shorter stature
• Delayed mental development or learning difficulties
• Less energy than usual
• A visible swelling in the neck

Symptoms in older adults

• Increased tiredness
• Memory problems or brain fog
• Slow heart rate
• Depression or low mood
• Swelling in the neck that may affect swallowing

Causes

Main causes

• Not eating enough foods that contain iodine
• Living in an area where the soil and water have very little iodine
• Eating large amounts of foods that block iodine use, like cassava, millet, or cabbage, in rare cases
• Pregnancy and breastfeeding, because the body needs extra iodine

Risk factors

• Following a vegan or very restricted diet without iodised salt
• Not using iodised salt at all
• Living in a region known for iodine-poor soil
• Being pregnant or breastfeeding
• Having a family history of thyroid disease

When to see a doctor

See a doctor urgently if:

• If you notice sudden swelling in your neck or have trouble breathing or swallowing
• If you feel dizzy, faint, or have palpitations with a slow heartbeat

Book a routine appointment if:

• If you have been tired, gained weight, or felt cold for several weeks without a clear reason
• If you have a lump or swelling in your neck
• If you are pregnant or planning to become pregnant and are worried about iodine

Diagnosis

A doctor will start by asking about your symptoms, diet, and any swelling in your neck. A physical exam of your neck and a simple urine or blood test can check your iodine levels and thyroid function.

Tests that may be done

• Urine sample to measure iodine in your body
• Blood test to check thyroid hormone levels
• Thyroid-stimulating hormone (TSH) blood test
• Ultrasound of the neck if the thyroid feels swollen

What to expect at your appointment

The tests are simple and painless. You may be asked to give a urine sample or have a blood draw. The doctor will usually get results within a few days. Based on the results, they can tell you whether you need more iodine or if there is another cause for your symptoms.

Treatment

Treatment focuses on getting enough iodine, and if your thyroid is already underactive, managing that with medication. The right approach depends on how low your iodine level is and whether you have developed thyroid problems.

Self-care at home

• Add iodised salt to your cooking in small amounts
• Eat older sources of iodine such as fish, shellfish, dairy, or eggs
• If you are vegan, consider foods like fortified plant milks and seaweed, but be careful with seaweed because iodine amounts can be very high
• Ask your pharmacist about a general iodine supplement only if your doctor recommends it

Medical treatments

In addition to diet changes, your doctor may recommend an iodine supplement in a specific dose that is right for you. If thyroid function has been affected, treatment may involve thyroid hormone replacement, which is a tablet you take daily. The dose is adjusted by your doctor and checked with blood tests over time. You should never take extra iodine supplements without medical advice, because too much iodine can also be harmful to the thyroid.

When is surgery considered?

Surgery is rarely needed for iodine deficiency. It may be considered only if a very large goitre presses on your windpipe or makes swallowing difficult, or if a nodule in the thyroid looks suspicious after tests.

Living with this condition

Living with iodine deficiency usually means paying attention to your diet and taking any prescribed treatment. With the right amount of iodine, most people feel better within a few months. It helps to have a routine for meals and to read food labels to see if iodised salt is used.

Lifestyle tips

• Cook with iodised salt (but do not overdo it – too much salt is unhealthy)
• Plan balanced meals with regular sources of iodine
• If you take supplements, take them at the same time each day as directed
• Keep a record of any symptoms to share with your doctor

Diet and exercise

Eating a variety of foods is the best way to get enough iodine. Fish, dairy and eggs are strong sources. For exercise, start gently – if you have been feeling very tired, brisk walking or light yoga can help your energy levels without overdoing it. Always check with your doctor before starting a new exercise routine if you have any heart symptoms.

Mental health and emotional wellbeing

Thyroid problems from iodine deficiency can cause low mood, poor concentration, and irritability. It is normal to feel frustrated or worried when your energy is low. These feelings often improve as your thyroid function returns to normal. If you feel anxious or depressed, talk to your doctor – they can support you and, if needed, refer you to a mental health professional.

Prevention

Yes, iodine deficiency can usually be prevented by getting enough iodine through your diet. Using iodised salt at the table and in cooking is one of the simplest ways. Pregnant women should talk to their doctor about whether they need a supplement, because the need is higher during pregnancy.

Screening programmes

In some countries, newborns are screened for thyroid function, which can detect iodine problems early. If you are pregnant or have a family history of thyroid disease, your doctor may recommend a blood test to check your thyroid hormone levels.

Complications

If left untreated

• Goitre – an enlarged thyroid gland that can make swallowing or breathing difficult
• Hypothyroidism – an underactive thyroid, which can slow your heart rate and metabolism
• In pregnancy – increased risk of miscarriage, stillbirth, or birth defects
• In children – impaired brain development and growth problems

Long-term outlook

With the right treatment and dietary changes, iodine deficiency is very manageable. The vast majority of people feel significantly better once their iodine levels return to normal. Goitres often shrink with treatment, and children who get enough iodine early can catch up on growth. The key is to follow your doctor's advice and keep up with check-ups.

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