Iodine

Aka: Iodine, Iodide, Lugol's Solution, Tincture of Iodine, Saturated Solution Potassium iodide, SSKI, Potassium Iodide

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II. Indications: Medical Uses

  1. Topical Antiseptic (Povidone-Iodine)
  2. Water Disinfection via Halogenation (Tincture of Iodine)
  3. Colposcopy (Lugol's Solution may better highlight lesions)
  4. Expectorant in COPD (SSKI)
  5. Hyperthyroidism
    1. Radioiodine (I-131) for Thyroid radioablation
    2. Radioactive Iodine Uptake Scan (I-123) for Hyperthyroidism diagnostic evaluation
    3. Thyroid Storm (Potassium Iodide/SSKI given after Beta Blocker and Thionamide)

III. Physiology

  1. Iodine
    1. Iodine (I) is an element with atomic number 53 and atomic weight 126.90
    2. Non-metal mineral in the halogen group
    3. Essential for Thyroid Hormone synthesis (but must be converted to the Iodide state)
    4. Iodine also has anti-infective properties allowing for use as an Topical Antiseptic and water disinfectant
    5. Potassium Iodide (SSKI) is given in Thyroid Storm
      1. Must be given after Thionamides (Methimazole, PTU), or increases T4 synthesis, worsening storm
      2. Iodine blocks release of stored T4 and decreases Iodine transport (Wolff-Chaikoff Effect)
      3. Effects are limited to 2 weeks (after which T4 secretion resumes again)
  2. Iodide
    1. Iodine Anion (I-) or salt
    2. In vivo synthesis of Thyroid Hormone (T4) requires Iodide
      1. Enzyme Thyroid peroxidase generates Iodide from Iodine
      2. Thionamides (Methimazole, PTU) block Thyroid peroxidase, thereby blocking T4 synthesis

IV. Medications

  1. See Povidone-Iodine (Betadine)
  2. See Radioiodine
  3. See Radioactive Iodine Uptake Scan
  4. Lugol's Solution
    1. Lugol's is a Iodine and Potassium Iodide solution used as a diagnostic agent in Colposcopy, as well as an antiseptic
    2. Iodine binds the alpha-1,4 glucans in Polysaccharides (e.g. glycogen)
      1. Glycogen is present in normal cells, but absent in dysplastic and cancer cells
      2. In Colposcopy, Lugol's stains normal cells brown
      3. Dysplastic and cancer cellsremain unstained, highlighted regions for biopsy
  5. Saturated Solution Potassium iodide (SSKI)
    1. Used in Thyroid Storm AFTER giving Beta Blocker and at least one hour after Thionamide (Methimazole or PTU)
      1. Dose: 5 drops (50 mg Iodide/drop) mixed in fluid or food every 6 hours for at least 2 days
    2. May be used as an expectorant in COPD
  6. Tincture of Iodine
    1. Used for histopathology stains
    2. Used historically as a Topical Antiseptic (replaced by products such as Povidone-Iodine)
    3. May be used for Water Disinfection of water by Halogenation (5-10 drops added to quart water)
      1. Found in some emergency survival kits for purification of water with high load of organic solute
    4. Available in 2-3% and 7% (strong) solutions
  7. Multivitamins
    1. Many Prenatal Vitamins contain 150 mcg Iodine

V. Dosing: Recommended Daily Allowance (RDA)

  1. Men and women: 150 mcg daily
  2. Pregnancy: 220 mcg daily
  3. Lactation: 290 mcg daily

VI. Precautions

  1. Iodine intake >500 mcg daily offers no benefit
  2. Iodine intake >1100 mcg daily may result in toxicity (inhibits Thyroid Hormone synthesis)

VII. Sources: Dietary

  1. Iodized Salt (400 mcg per 1 tsp)
    1. Not all salt is iodized (check labeling)
  2. Dairy
    1. Cows Milk (60 mcg per 8 oz)
    2. Soy Milk
    3. Cheese
    4. Yogurt
    5. Ice Cream
  3. Seafood
    1. Pregnant women should avoid excessive fish (see Mercury Content in Fish)
    2. Saltwater Fish (e.g. Cod contains 100 mcg per 3 oz)
    3. Shellfish
  4. Miscellaneous
    1. Eggs
    2. Seaweed (e.g. kelp)
    3. Soy sauce

VIII. Resources

  1. Thyroid.org
    1. http://www.thyroid.org/iodine-deficiency/
  2. Wikipedia
    1. http://en.wikipedia.org/wiki/Iodine
  3. Saturated Solution Potassium iodide (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=664e6cd9-6a3c-49ef-a7b2-d09f0338b549
  4. Potassium Iodide (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d9e02a48-8129-9076-78b2-db01750bd220
  5. Tincture of Iodine (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=c75f84a1-5edf-4952-858d-3ca63727a0ce

IX. References

  1. (2015) Presc Lett 22(5): 25-6

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Cost: Medications

iodine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
IODINE 2% MILD TINCTURE Generic OTC $0.07 per ml
iodide (on 11/23/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
IODIDES TINCTURE Generic OTC $0.07 per ml
FPNotebook does not benefit financially from showing this medication data or their pharmacy links. This information is provided only to help medical providers and their patients see relative costs. Insurance plans negotiate lower medication prices with suppliers. Prices shown here are out of pocket, non-negotiated rates. See Needy Meds for financial assistance information. GoodRx is another tool for finding lower drug prices.

Related Topics in Minerals and Other Inorganic Chemicals

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