ASK DIS: Lugol’s Solution in Thyroid Storm

Tuesday, July 14, 2015

Contains 100 mg potassium iodide and 50 mg iodine; provided 8 mg iodide/drop, 20 drops per ml
Mechanism of Action:

Lowering circulating (thyroid Hormone) TH’s levels is achieved either preventing TH’s synthesis or blocking TH’s release.
Both propylthiouracil (PTU) and methimazole (MMI) inhibit the synthesis of new TH interfering with the iodide oxidation and organification process. The effect is delayed in 3-4 days.
Inorganic iodine preparations block the TH’s release by inhibiting thyroglobulin protheolysis (Wolff-Chaikof effect).
The iodine therapy must be administered after successful inhibition of new TH’s synthesis is achieved (2-3 h after PTU or MMI administration) since the use of iodine alone would lead to enhance intraglandular TH’s stores and possible worsening of the thyrotoxic crisis (escape phenomenon)

Dose

4-8 drops every 6-8 hours; begin administration ≥1 hour following the initial dose of either propylthiouracil or methimazole OR
0.3 mL of strong iodine solution (Lugol's solution) 3 times daily (range, 0.1 to 0.9 mL daily) OR
10-20 drops 8 hourly (Sarawak Handbook of Medical Emergencies) OR
In the UK, many experts prescribe 1 ml of Lugol's solution orally every 6 hours.

Recommendation

Most guides are consistent with the lower drops of Lugol’s Solution (up to 10 drops). The higher amount (20 drops) Is seen in the management of thyroid storm in pregnant patient.
None of the guidelines recommended any duration of action.
Iodides can be discontinued after initial improvement

References:

ASK DIS