A 24-year-old female presents with severe agitation, profuse sweating, palpitations, and fever (39.5°C). Examination reveals a diffuse goiter with a bruit, exophthalmos, atrial fibrillation with ventricular rate 160 bpm, and mild jaundice. Burch-Wartofsky score is 65 (highly suggestive of thyroid storm). What is the first-line medication administered to inhibit new thyroid hormone synthesis?

Answer and explanation

Correct answer: A. Propylthiouracil (PTU)

  1. Step 1: In Thyroid Storm, pharmacotherapy follows a strict multi-drug hierarchy:
  2. Step 2: 1. Thionamides (Propylthiouracil / PTU or Methimazole) are administered FIRST to block new thyroid hormone synthesis.
  3. Step 3: PTU is specifically preferred in thyroid storm because it also inhibits peripheral conversion of T4 to T3.
  4. Step 4: 2. Iodine solutions (Lugol's or SSKI) must be given at least 1 hour AFTER thionamides to prevent the Wolff-Chaikoff effect from failing (iodine would otherwise fuel new hormone synthesis).
  5. Step 5: 3. Beta-blockers (propranolol) control adrenergic hyperactivity, and corticosteroids block peripheral conversion and treat relative adrenal insufficiency.
Answer
Propylthiouracil (PTU).
Why not the others: 'Potassium Iodide (SSKI)' must be given at least 1 hour AFTER thionamides to avoid providing substrate for new hormone synthesis; 'Hydrocortisone' blocks peripheral conversion and supports adrenals but is not the primary thionamide; 'Propranolol' blocks beta-adrenergic symptoms without inhibiting thyroid hormone synthesis.

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