II. Indications: Medical Uses
- Topical Antiseptic (Povidone-Iodine)
- Water Disinfection via Halogenation (Tincture of Iodine)
- Colposcopy (Lugol's Solution may better highlight lesions)
- Expectorant in COPD (SSKI)
-
Hyperthyroidism
- Radioiodine (I-131) for Thyroid radioablation
- Radioactive Iodine Uptake Scan (I-123) for Hyperthyroidism diagnostic evaluation
- Thyroid Storm (Potassium Iodide/SSKI given after Beta Blocker and Thionamide)
III. Physiology
- Iodine
- Iodine (I) is an element with atomic number 53 and atomic weight 126.90
- Non-metal mineral in the halogen group
- Essential for Thyroid Hormone synthesis (but must be converted to the Iodide state)
- Iodine also has anti-infective properties allowing for use as an Topical Antiseptic and water disinfectant
- Potassium Iodide (SSKI) is given in Thyroid Storm
- Must be given after Thionamides (Methimazole, PTU), or increases T4 synthesis, worsening storm
- Iodine blocks release of stored T4 and decreases Iodine transport (Wolff-Chaikoff Effect)
- Effects are limited to 2 weeks (after which T4 secretion resumes again)
- Iodide
- Iodine Anion (I-) or salt
- In vivo synthesis of Thyroid Hormone (T4) requires Iodide
- Enzyme Thyroid peroxidase generates Iodide from Iodine
- Thionamides (Methimazole, PTU) block Thyroid peroxidase, thereby blocking T4 synthesis
IV. Medications
- See Povidone-Iodine (Betadine)
- See Radioiodine
- See Radioactive Iodine Uptake Scan
- Lugol's Solution
- Lugol's is a Iodine and Potassium Iodide solution used as a diagnostic agent in Colposcopy, as well as an antiseptic
- Iodine binds the alpha-1,4 glucans in Polysaccharides (e.g. glycogen)
- Glycogen is present in normal cells, but absent in dysplastic and cancer cells
- In Colposcopy, Lugol's stains normal cells brown
- Dysplastic and cancer cellsremain unstained, highlighted regions for biopsy
- Saturated Solution Potassium iodide (SSKI)
- Used in Thyroid Storm AFTER giving Beta Blocker and at least one hour after Thionamide (Methimazole or PTU)
- Dose: 5 drops (50 mg Iodide/drop) mixed in fluid or food every 6 hours for at least 2 days
- May be used as an expectorant in COPD
- Used in Thyroid Storm AFTER giving Beta Blocker and at least one hour after Thionamide (Methimazole or PTU)
- Tincture of Iodine
- Used for histopathology stains
- Used historically as a Topical Antiseptic (replaced by products such as Povidone-Iodine)
- May be used for Water Disinfection of water by Halogenation (5-10 drops added to quart water)
- Found in some emergency survival kits for purification of water with high load of organic solute
- Available in 2-3% and 7% (strong) solutions
-
Multivitamins
- Many Prenatal Vitamins contain 150 mcg Iodine
V. Dosing: Recommended Daily Allowance (RDA)
- Men and women: 150 mcg daily
- Pregnancy: 220 mcg daily
- Lactation: 290 mcg daily
VI. Precautions
- Iodine intake >500 mcg daily offers no benefit
- Iodine intake >1100 mcg daily may result in toxicity (inhibits Thyroid Hormone synthesis)
VII. Sources: Dietary
-
Iodized Salt (400 mcg per 1 tsp)
- Not all salt is iodized (check labeling)
- Dairy
- Cows Milk (60 mcg per 8 oz)
- Soy Milk
- Cheese
- Yogurt
- Ice Cream
- Seafood
- Pregnant women should avoid excessive fish (see Mercury Content in Fish)
- Saltwater Fish (e.g. Cod contains 100 mcg per 3 oz)
- Shellfish
- Miscellaneous
- Eggs
- Seaweed (e.g. kelp)
- Soy sauce
VIII. Resources
- Thyroid.org
- Wikipedia
- Saturated Solution Potassium iodide (DailyMed)
- Potassium Iodide (DailyMed)
- Tincture of Iodine (DailyMed)
IX. References
- (2015) Presc Lett 22(5): 25-6
Images: Related links to external sites (from Bing)
Related Studies
| 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 |