Potassium Iodide (KI) is a salt of iodine. It is one of several ingredients that can be added to table salt to make it iodized. KI has also been approved by the FDA as a nonprescription drug for use as a "blocking agent" to prevent the human thyroid gland from absorbing radioactive iodine. However, KI may not provide people with 100% protection against all radioactive iodine. Its effectiveness will depend on a variety of factors, including when a person takes it, how much iodine is already in the person's thyroid, how fast the person's body processes it, and the amount of radioactive iodine the person is exposed to. Iodized table salt will not provide enough iodine to protect the thyroid and should not be used as a substitute.

Facts About the Thyroid Gland
     The thyroid is a small gland located in a person's neck on either side of the breathing tube (trachea). The thyroid has two parts, a right lobe and a left lobe, that are connected by a small strip of tissue called the isthmus. The main function of the thyroid gland is to create, store, and release thyroid hormones. These hormones regulate the body's metabolism.

Why Iodine is Impotant in the Thyroid
     The thyroid gland takes iodine from the bloodstream and uses it to make thyroid hormones. Without the required amounts of iodine, the thyroid will not be able to make these hormones. Most of the iodine in people's bodies comes from the food they eat.

How a Nuclear Incident Might Cause Thyroid Damage
    Some types of radioactive incidents release radioactive iodine. The thyroid gland, which will use any iodine that is in a person's bloodstream, cannot tell the difference between radioactive and nonradioactive forms of iodine. Because of this, the thyroid would rapidly absorb radioactive iodine just as it does iodine from a person's diet. The radioactive iodine releases energy (radiation) that, in high concentrations, can damage the cells of the thyroid gland. In some people, especially young children, this damage can cause thyroid cancer or other diseases of the thyroid within a few years of the exposure.

The Imporance of Potassium Iodide in the Event of a Nuclear Accident
     Because the thyroid will rapidly absorb any iodine that is in the body, people may need to take KI tablets soon after an incident that involves radioactive iodine. The KI will saturate the thyroid gland with iodine and help prevent it from absorbing radioactive iodine. However, KI does not prevent the effects of other radioactive elements. Using KI will only protect the thyroid gland from radioactive iodine. It will not protect other parts of the body from radioactive iodine, and it will not protect a person from other radioactive materials that may be released.

Taking potassium iodide (KI)
      Potassium iodide only protects a person’s thyroid gland from exposure to radioactive iodine. KI will not protect a person from other radioactive materials or protect other parts of the body from exposure to radiation. It must be taken prior to exposure (for example, if people hear that a radioactive cloud is coming their way) or immediately after exposure to be effective.
      Local emergency management officials will tell people when to take KI. If a nuclear incident occurs, officials will have to find out which radioactive substances are present before recommending that people take KI. Also, KI can be dangerous to some people. Taking KI is not recommended unless there is a risk of exposure to radioactive iodine. If radioactive iodine is not present, then taking KI will not protect people. If radioactive iodine is present, then taking KI will help protect a person's thyroid gland from the radioactive iodine. Taking KI will not protect people from other radioactive substances that may be present along with the radioactive iodine.
      The Food and Drug Administration (FDA) recommends that KI be taken as soon as the radioactive cloud containing iodine from the explosion is close by. KI may still have some protective effect even if it is taken 3 to 4 hours after exposure to radioactive iodine. Because the radioactive iodine will be present in the initial blast and decays quickly, a single dose of KI may be all that is required.

Forms and Doses Of Potassium Iodide
     KI comes in tablets of 130 mg. A one-time dose at the levels recommended in this fact sheet is usually all that is required. However, if a person expects to be exposed to radioactive iodine for more than 24 hours, another dose should be taken every 24 hours. People should listen to emergency management officials for recommendations after an incident. According to the FDA,

   -Adults should take one 130-mg tablet.
   -Children between 3 and 18 years of age should take one-half of a 130-mg tablet (65 mg).
   -Children between 1 month and 3 years of age should take one-fourth of a 130-mg tablet
    (32 mg).
   -Infants from birth to 1 month of age should be given one-eighth of a 130-mg tablet
    (16 mg).
   -Women who are breastfeeding should take the adult dose, and their infants should receive the recommended infant dose.
   -Children who are approaching adult size (greater than or equal to 150 pounds) should take  the adult dose regardless of their age.

KI tablets can be stored for at least 5 years without losing their potency.

People should remember that taking a higher dose of KI, or taking KI more often than recommended, will not offer more protection and can cause severe illness and death due to allergic reaction.

Medical Conditions That Make it Dangerous to Take KI
The high concentration of iodine in KI can be harmful to some people.
People should not take KI if they:
  -have ever had thyroid disease (such as hyperthyroidism, thyroid nodules, or goiter).
  -know they are allergic to iodine (as in x-ray dye or shellfish).
  -have certain skin disorders (such as dermatitis herpetiformis or urticaria vasculitis).

People should consult their doctor if they are unsure whether or not to take KI.

                   
           

                  All information obtained from the CDC (Center for Disease Control and Prevention)