Iodine deficiency

iodine deficiencyIodine deficiency is a condition of the insufficient iodine level in the body.

Description

Iodine is a microelement necessary for the production of the thyroid hormones, which contain iodine.

Iodine deficiency disorders include conditions caused by the iodine deficiency such as the endemic goiter, hypothyroidism, cretinism, decreased fertility rate, increased infant mortality, and mental retardation.

Causes

In different areas of the world the soil appears deficient in iodine. It was estimated the 29% of the world’s population from 130 countries live in the areas of iodine deficiency that are called endemic.

Iodine is a substance used for the production of thyroxine (T4) and triiodothyronine (T3). These hormones are necessary for the development of the nervous and reproductive systems, growth, they regulate the metabolic rate, body heat, and energy.

Risk factors

Risk factors for iodine deficiency are the following:

  • Low intake of iodine with foods, living in the endemic area;
  • Selenium deficiency;
  • Pregnancy as the child requires iodine for its development;
  • Exposure to radiation;
  • Increased intake of the substances known as goitrogens (for example, calcium);
  • Gender (higher incidence in women);
  • Smoking;
  • Alcohol abuse;
  • Oral contraceptives intake;
  • Perchlorates;
  • Thiocyanates;

Recommended daily intake and the sources

Normal dietary iodine intake is 100-150 mcg/day.  According to The US Institute of Medicine’s (IOM’s) recommended dietary allowance of iodine are the following:

  • Adults and adolescents – 150 mcg/day;
  • Pregnant women – 220 mcg/day;
  • Lactating women – 290 mcg/day;
  • Children aged 1-11 years – 90-120 mcg/day;
  • Infants – adequate intake is 110-130 mcg/day;

Sources of iodine include:

  • saltwater fish;
  • seaweed;
  • grains;
  • table salt in the countries where iodine is added as a supplement;
  • egg yolk;
  • milk;


Symptoms

  • Goiter (enlarged thyroid gland)- usually diffuse in children and nodular in adults. May be asymptomatic or compress the larynx and irritate the nerves and  therefore cause hoarseness, shortness of breath, cough, or dysphagia (so called compressive symptoms);
  • Hypothyroidism (in severe cases called myxedema) is characterized by the following symptoms: lethargy and tiredness, muscule weakness and fatigue, cold intolerance (feeling cold even when it’s warm), difficulties to concentrate, poor memory, forgetfullness, weight gain, depression, thick skin or puffiness of the face, hair loss (alopecia), dry skin, constipation, bradycardia (slow heart rate), in severe cases all the body appears swollen;
  • Cretinism develops when a child doesn’t get enough iodine. Two types of cretinism are distinguished. Neurologic cretinism is  caused by severe hypothyroidism of the mother during pregnancy. The newborn child fails to develop normally – mental retardation, abnormal gait, and deaf-mutism develops. Myxedematous cretinism is a caused by the iodine deficiency and hypothyroidism in the fetus during third trimester of pregnancy or in the neonatal period, mental retardation, short stature, goiter are the common signs of hypothyroidism.
  • Mental retardation – It is suggested that iodine deficiency is the most preventable cause of mental disability.

See also: Vitamin B2 deficiency, Thyroid test

Diagnosis

Hormone level is measured (T3, T4 and TSH) to verify the dysfunction of the gland. Ultrasound examination and biopsy of the gland is recommended to explore its structure. The best diagnostic test to identify an iodine deficiency in a population is a median 24-hour urine iodine collection.

Prevention

To prevent the iodine deficiency in population some foods and water supply may be iodized, usually it’s salt.

Treatment

If there is no hormonal disbalance or it is light iodine supplements iodine-rich food may be used to treat the deficiency.

In severe cases, replacement therapy with levothyroxine is recommended. If the goiter is too large and compresses the larynx, thyroidectomy is suggested  to be the option.