Low levels of iodine and hypothyroidism are directly and unavoidably related. Hypothyroidism is a syndrome of the thyroid gland in which the gland ceases to produce the amount of hormone that is required by the body to carry out many major functions. These hormones are T3 (triiodothyronine) and T4 (thyroxine) and they control our growth, reproduction and metabolism processes.
One of the raw ingredients needed to produce these thyroid hormones is iodine. The adult human body normally has around 20 mgs of iodine, 80% of which is stored in the thyroid. Thyroid tissue is the only type of tissue that can absorb iodine. The thyroid combines iodine with the amino acid tyrosine to produce the two hormones. Therefore, without iodine the thyroid can’t produce thyroid hormones. This is why iodine deficiency is the major global cause of hypothyroidism, although these days it’s typically seen predominately in developing countries. In developed countries the autoimmune condition Hashimoto’s disease is now the leading cause of hypothyroidism.
Iodine and Hypothyroidism – Treating Iodine Deficiencies
The tragedy of iodine caused hypothyroidism is that iodine deficiencies are relatively easy to fix! Even though it’s a vital ingredient in producing thyroid hormone, we actually require very little of it. The average person will only ever need around one teaspoon full in their entire life. Most authorities recommend that adults should ensure they get 150μg of iodine daily. Less than a third of a teaspoon of iodized salt daily will supply this. Pregnant and lactating women require more.
Alternatively, ensuring you eat either iodine fortified foods like dairy or bread products, or foods that naturally contain iodine, will also help make up that recommended daily allowance. There are several foods that are good sources of iodine:
- Seaweed or kelp
- Cod, tuna and shrimp
- Iodine fortified bread
Taking in excessive amounts of iodine however is not good for you either. It can cause some of the same symptoms as iodine deficiency, notably goiter. It can also cause thyroid cancer and inflammation in the thyroid. Whilst iodine supplements are available, it’s not advisable to take them if you’re already getting sufficient iodine in your diet, which is the preferred way to get it.
Interesting Questions about Thyroid:
What do antithyroid drugs do?
Antithyroid drugs block pathways leading to thyroid hormone production.
Antithyroid drugs used in this country are Propylthiouracil (PTU) and Tapazole®. Some physicians will recommend antithyroid medication as a first line of treatment to see if the patient is one of the lucky 30% of patients who go into a remission after taking antithyroid medication for one to two years. (Patients are said to be in remission if their hyperthyroidism does not recur after discontinuing the antithyroid drugs.) If antithyroid drugs do not work for the patient, then physicians usually recommend radioactive iodine.
Antithyroid drugs are also used to treat very young children, older patients with heart conditions, and pregnant women. For severe or complicated cases of hyperthyroidism, especially in older patients, PTU or Tapazole® can be given for four to six weeks to bring the hyperthyroidism under better control prior to administering radioactive iodine treatment.
In cases when women are diagnosed with Graves’ disease while they are pregnant, PTU is prescribed. The smallest dose possible is given because the medication does cross over to the fetus. The mother should be checked every three to four weeks during the pregnancy so that the lowest possible dose can be given. Too much PTU can cause fetal goiter, hypothyroidism, and mental retardation.
® Tapozole is a registered trademark of Jones Medical Industries.
Are there any side effects?
Antithyroid drugs cause side effects in about 10% of patients. Reactions can include:
- skin rash
- swollen, stiff, painful joints
- sore throat and fever
- low white blood count, which can lead to serious infections
- jaundice (yellow coloring of the skin) and, rarely, liver failure.
Most side effects clear up once the drugs are stopped. If you think you are having a reaction to anti-thyroid drugs, call your doctor immediately.
What can be expected with antithyroid drug treatment?
- Several pills are taken from one to four times a day, every day for six to 24 months.
- Some patients complain that the pills have an unpleasant smell and taste.
- There is usually some symptom relief within one to two weeks. In some cases, it can take several months to relieve symptoms.
- Antithyroid drugs have a relatively low success rate. While PTU or Tapazole® may correct the problem temporarily or for a few years, the chances of a permanent remission are about 30% once the drugs are stopped.
- The likelihood of achieving a permanent remission is increased if the patient takes the medication for one to two years.
- There are side effects in 10% of the people treated with Tapazole® or PTU. These are:
- skin rash over most of the body swollen, stiff, painful joints
- sore throat and fever — if this happens, the antithyroid drugs should be stopped immediately and the physician contacted
- liver damage, which is fatal in rare cases
- Because antithyroid drugs pass into breast milk, only PTU in a dosage less than 200 mg a day is advised if the baby is not weaned.
- Within 15 years, the thyroid gland may burn out, resulting in hypothyroidism, and the patient will need thyroid hormone replacement.
Signs and symptoms of Hyperthyroidism may include:
- fast heart rate (100-120 beats per minute or higher)
- slightly elevated blood pressure
- nervousness or irritability
- increased perspiration
- muscle weakness (especially in the shoulders, hips, and thighs)
- trembling hands
- weight loss, in spite of a good appetite
- hair loss
- fingernails partially separated from finger-tips (onycholysis)
- swollen fingertips (achropachy or clubbing)
- retracted (pulled back) upper eyelids
- skin changes
- increased frequency of bowel movements
- goiter (an abnormal swelling in the neck caused by an enlarged thyroid gland)
- in women, decreased menstrual flow and less frequent menstrual flow
- in men, slight swelling of the breasts
- in Graves’ disease: thick or swollen skin over the shin bones (pretibial myxedema); eyes that seem to be popping out of their socket (exophthalmos).
Most of these conditions will return to normal after the hyperthyroidism is treated. Certain others may be treated separately.
When are beta-blocking drugs used?
Beta-blocking drugs, also called beta blockers, treat the symptoms of hyperthyroidism. They do not significantly affect the gland or the levels of thyroid hormones in the blood. Instead, they “block” the effects of thyroid hormones.
Beta blockers are most useful for patients whose hyperthyroidism makes them uncomfortable. High hormone levels can cause a faster heart rate and trembling. Beta-blocking drugs help control these symptoms.
Beta-blocking drugs should not be used by patients with asthma.
Have more questions? Need more answers? Check our Full Thyroid FAQ
Iodine And Hypothyroidism – Transient Congenital Hypothyroidism
Transient congenital hypothyroidism is a condition in new born infants where they’re born with, or develop, a decreased ability to produce their own thyroid hormones. One of the known causes of this condition is exposure to iodine either during the birthing process or directly afterwards by way of skin applications of iodine based disinfectants (treating the umbilical stump etc).
As always, if you suspect you have a thyroid disorder it’s important to get yourself checked out thoroughly.