In the management of a thyroid storm, when should iodine be administered?

In the management of a thyroid storm, iodine should be administered after propylthiouracil (PTU) because of the timing of its action and the way it helps control the condition. PTU works by inhibiting the synthesis of new thyroid hormones, while iodine provides an immediate source of iodide that can suppress thyroid hormone release once the hormone synthesis is halted.

If iodine is given before PTU, it may lead to the release of preformed thyroid hormones from the thyroid gland, worsening the storm temporarily. Thus, administering PTU first allows for the suppression of hormone synthesis, and then iodine can be added to further control the release of thyroid hormones from the gland, which is essential in effectively managing a thyroid storm.

This sequence optimizes the therapeutic effect of both medications while avoiding any counterproductive effects that could arise from the premature administration of iodine.