admittomedicine

potassium iodide

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acute thyroid blockade

Inorganic iodine. Paradoxically inhibits thyroid hormone release/synthesis acutely. Used for rapid control in Thyroid Storm and to reduce vascularity prior to Thyroidectomy.

  • Mechanism:
    1. Wolff-Chaikoff Effect: Acute inhibition of organification (synthesis).
    2. Inhibits Release: Blocks proteolysis of thyroglobulin (rapid T4/T3).
    3. Decreases Vascularity: Makes gland firmer/less bloody for surgery.
  • Dosing:
    • Thyroid Storm: 5 drops SSKI q6h or 10 drops Lugol’s q8h.
    • Pre-op Graves: 5–7 drops Lugol’s TID x 10 days before surgery.
  • PK: Effects are transient (“Escape” phenomenon occurs after ~10-14 days).

indications

  • Thyroid Storm: Give >1 hour AFTER Thionamide (to prevent Jod-Basedow fueling).
  • Pre-operative Prep: For Graves’ disease thyroidectomy.
  • Nuclear Emergency: Blocks uptake of radioactive isotopes.

cautions

  • Timing: Do not give before Antithyroid Drugs in hyperthyroidism.
  • Jod-Basedow: Can precipitate hyperthyroidism in MNG.
  • Fetal Goitre: Crosses placenta; avoid prolonged use in pregnancy.

related pages: Thyroid Storm, graves’ disease

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