What is Potassium Iodide?
Potassium iodide (KI) is a salt of the essential mineral iodine. Your body needs iodine to synthesize the hormones thyroxine (T4) and triiodothyronine (T3). These two hormones are vitally important for normal development, growth and metabolism.
T4 and T3 are produced by the thyroid gland: a small, butterfly-shaped organ located in the neck. These hormones are made by specialized structures called “thyroid follicles,” and then released into the bloodstream.
What is It Used For?
KI is used as a nutritional supplement for both humans and animals. It’s routinely added to livestock feeds, fortified foods, multivitamin formulas and iodized salt.
Iodine deficiency is a serious public health problem in many parts of the world, so potassium iodide supplementation—particularly in the form of iodized salt—is vital for preventing iodine deficiency disorders (IDDs). IDDs are responsible for widespread health problems, including neurological and cognitive damage, impaired growth, goiter and hypothyroidism.
KI has pharmaceutical uses too. It’s used for medical imaging, as an emergency treatment for hyperthyroidism (“thyroid storm“), as an expectorant, and as a treatment for cutaneous sporotrichosis (a fungal skin infection).
Just as importantly, KI can be used to protect your thyroid gland from exposure to the radioactive iodine released during a nuclear accident or emergency.
Serious nuclear power plant accidents, such as Chernobyl (Ukraine, 1986), Three Mile Island (US, 1979) and Fukushima (Japan, 2011), typically release gaseous iodine-131 (131I) into the atmosphere, where it can drift for miles beyond the point of origin.
Although the half-life of 131I is relatively short (~8 days), once inhaled or ingested (via contaminated food), it can be taken up by the thyroid gland, just like stable (non-radioactive) iodine is.
The resulting radiation damage dramatically increases the risk of developing thyroid disease—including cancer.
And the risk to infants and children is even higher than that of adults.
How Does It Protect from Radioactive Iodine?
How does KI protect the thyroid from 131I?
FDA-approved supplements provide KI in a dose (130mg) that provides iodine far in excess of the RDA (150ug for adults). This floods the thyroid with stable iodine, and effectively blocks uptake of the radioactive isotope.
The unabsorbed 131I is then rapidly excreted in urine. While KI intake does not protect against exposure to other radionuclides (such as strontium-90, plutonium-239 or cesium-137), it can help prevent one of the best-known threats to health caused by nuclear fallout.
Taking protective doses of KI is not without risk, however, which is why strict guidelines for usage have been developed by the US FDA and other agencies throughout the world (such as WHO).
According to the US Centers for Disease Control (CDC), taking KI could be harmful to people with allergies to iodine or who have certain skin disorders. In addition, those with pre-existing thyroid disease, or who are taking specific prescription drugs (lithium, warfarin/coumadin or anti-thyroid medications) should take it only under medical supervision.
KI can cause side effects in healthy people too, such as upset stomach, skin rash and/or inflamed salivary glands. While large doses of KI are safe when taken over the recommended period of time (14 days), longer-term use can induce hypothyroidism.
In summary: thyroid-protective doses of KI should be taken only when the radiation exposure warrants it, for no more than the prescribed period of time and in age-appropriate amounts.
Dosing Guidelines
These are the dosing guidelines, according to the FDA:
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| Predicted Thyroid gland exposure (cGy) | KI dose (mg) | Number or fraction of 130 mg tablets | Number or fraction of 65 mg tablets | Milliliters (mL) of oral solution, 65 mg/mL*** | |
|---|---|---|---|---|---|
| Adults over 40 years |
> 500 | 130 | 1 | 2 | 2 mL |
| Adults over 18 through 40 years |
> 10 | 130 | 1 | 2 | 2 mL |
| Pregnant or Lactating Women |
> 5 | 130 | 1 | 2 | 2 mL |
| Adolescents, 12 through 18 years* |
> 5 | 65 | ½ | 1 | 1 mL |
| Children over 3 years through 12 years |
> 5 | 65 | ½ | 1 | 1 mL |
| Children 1 month through 3 years |
> 5 | 32 | Use KI oral solution** | ½ | 0.5 mL |
| Infants birth through 1 month |
> 5 | 16 | Use KI oral solution** | Use KI oral solution** | 0.25 mL |
* Adolescents approaching adult size (> 150 lbs) should receive the full adult dose (130 mg)
** Potassium iodide oral solution is supplied in 1 oz (30 mL) bottles with a dropper marked for 1, 0.5, and 0.25 mL dosing. each mL contains 65 mg potassium iodide.
*** See the Home Preparation Procedure for Emergency Administration of Potassium Iodide Tablets to Infants and Small Children.
* * * * * * * * * * * * * * * * * * * *
FDA-approved brands of protective KI supplements are Iosat, ThyroSafe and ThyroShield.
I Live in North America. Should I Be Taking KI to Protect Myself From the Fukushima Reactor Fallout?
Various media outlets have reported a surge in KI purchases in the continental US… as well as an increase in the number of KI-related calls to poison control centers. Although the Fukushima accident is serious and has yet to be resolved, there is little reason to be concerned for your own health/safety. Given the very long distance (over 5,000 miles to the coast of California) and relatively short half-life of 131I, it’s highly unlikely that harmful levels will reach the West Coast or other areas in the continental United States.
Public health authorities in the US and Canada strongly recommend that consumers NOT take KI at this time.
People interested in general emergency preparedness should avoid buying (useless) homeopathic preparations and potentially fake KI products from unreliable online marketers.
For general health and disease-prevention, most people living in iodine-sufficient countries will not need to take KI (or any other standalone iodine supplement). However, a product supplying the RDA for iodine may be needed for those on sodium-restricted diets lacking in iodine-rich foods (such as milk, eggs, seafood and seaweed) or other fortified, functional food products.
