Endocrine · Topic 6 of 13

Thyroid Storm

Endocrine · thyroid emergency

Thyroid Storm

Thyrotoxicosis with organ decompensation, diagnosed clinically. Block the adrenergic surge, stop synthesis, then block release with iodine, and add steroids.

Key numbers

Burch–Wartofsky score 45 or moreBWPS ≥ 45

Iodine at least 1 hour after thionamideiodine ≥ 1 h later

PTU is the preferred thionamide in stormPTU 500–1000 mg load

01 · Defined byBurch–Wartofsky score 45 or more

Burch–Wartofsky Point Scale (temperature, CNS, heart rate, GI-hepatic, heart failure, AF, precipitant): ≥ 45 highly suggests storm, 25–44 suggests impending storm, < 25 makes it unlikely.

02 · FirstIodine at least 1 hour after thionamide

Order matters: beta-blocker, then a thionamide to stop synthesis, then iodine at least 1 hour later to block release, plus a glucocorticoid. Iodine given first adds substrate and can worsen thyrotoxicosis.

03 · GivePTU is the preferred thionamide in storm

Give propylthiouracil 500–1000 mg load, then 250 mg every 4 hours (oral, NG or rectal) — it also blocks peripheral T4-to-T3 conversion; methimazole 60–80 mg/day is an acceptable alternative.

Causes & risk factors

Why it happens

Find and treat the precipitantStorm occurs in untreated or undertreated Graves disease or toxic multinodular goiter and is triggered by infection, surgery, trauma, stopping antithyroid drugs, iodine exposure (contrast, amiodarone), DKA or preeclampsia; treat the trigger.

Diagnosis & monitoring

Work-up

Thyroid storm is a clinical diagnosis must knowThyroid storm is severe thyrotoxicosis with decompensation — fever, tachycardia or AF with heart failure, agitation to coma, vomiting, diarrhea or jaundice. Hormone levels overlap with uncomplicated thyrotoxicosis, so treat on clinical grounds.

Track free T4 and T3, not TSHExpect free T4 and free T3 to fall progressively over several days; TSH stays suppressed for weeks and should not guide early treatment.

Watch thionamides for agranulocytosis and hepatotoxicityThionamides cause agranulocytosis (about 0.1%; never switch to the other thionamide after it) and PTU causes severe liver failure, so switch PTU to methimazole once the crisis settles.

Do right now

In this order

First moves

Give propranolol 60–80 mg every 4 hours

→

PTU is the preferred thionamide in stormPTU 500–1000 mg load

→

Then give SSKI or Lugol's iodine

→

Add IV hydrocortisone

Why each step

Give propranolol 60–80 mg every 4 hoursPropranolol 60–80 mg orally every 4 hours (ATA; Merck allows every 4–6 hours), or 0.5–1 mg IV slowly under monitoring, controls heart rate and tremor and at high doses also reduces peripheral T4-to-T3 conversion.

PTU is the preferred thionamide in stormGive propylthiouracil 500–1000 mg load, then 250 mg every 4 hours (oral, NG or rectal) — it also blocks peripheral T4-to-T3 conversion; methimazole 60–80 mg/day is an acceptable alternative.

Then give SSKI or Lugol's iodineAfter the thionamide, give saturated solution of potassium iodide 5 drops (0.25 mL) orally every 6 hours or Lugol's solution 4–8 drops every 6–8 hours; pharmacologic iodine blocks thyroid hormone release within hours.

Add IV hydrocortisoneGive hydrocortisone 300 mg IV load, then 100 mg every 8 hours (or dexamethasone 2 mg IV every 6 hours): glucocorticoids block T4-to-T3 conversion and cover relative adrenal insufficiency.

Management

Orders

Support with ICU care, fluids and dextroseManage in the ICU: IV fluids with dextrose, correct electrolytes, cooling blanket, and rate control of atrial fibrillation; involve endocrinology early.

Refractory storm: plasma exchange or thyroidectomyIf storm persists despite maximal therapy, consider cholestyramine (4 g three times daily), lithium, therapeutic plasma exchange as a bridge, ECMO, or emergency thyroidectomy; plan definitive radioiodine or surgery after control.

Red flags & don'ts

Avoid harm

Use acetaminophen, never aspirin, for fever avoidCool the patient and give acetaminophen; avoid aspirin because salicylates displace thyroid hormone from binding proteins and raise free T4 and T3.

Heart failure: titrate IV esmolol cautiously avoidIn thyrotoxic heart failure or shock, beta-blockade can cause cardiovascular collapse: use lower doses with invasive monitoring, preferring IV esmolol (500 mcg/kg load, 50–100 mcg/kg/min) because it can be stopped quickly.

PTU or methimazole?

Commonly confused

Blocks T4 → T3 conversion	Yes, at high doses
Storm dosing	500–1000 mg load, then 250 mg every 4 h
Main toxicity	Severe hepatotoxicity; agranulocytosis
Pregnancy	First trimester
Long-term use	Switch off after the crisis

More detail

Reference

Show 5 reference facts

In-hospital mortality is roughly 5–25% despite treatment; older age, neurologic impairment at admission and failure to give a thionamide and beta-blocker predict death.

Japanese guidelines favor beta1-selective agents (landiolol, esmolol IV; bisoprolol orally) over propranolol after a retrospective signal of higher mortality with propranolol in heart failure; later cohort data found similar mortality.

Methimazole is the preferred long-term thionamide (once daily, less agranulocytosis below 20 mg/day); PTU is reserved for thyroid storm and the first trimester of pregnancy.

No IV thionamide exists in the US: give PTU or methimazole by mouth, nasogastric tube or rectally in the obtunded patient.

The Japan Thyroid Association/Japan Endocrine Society criteria classify definite (TS1) or suspected (TS2) storm and are an alternative to the Burch–Wartofsky scale.

Pearl

Thionamide before iodine: iodine given first becomes fuel for more hormone.

Sources · Merck Manual Professional — Hyperthyroidism (incl. table: Treatment of Thyroid Storm), Jan 2026 · Taylor P et al. Management of thyroid emergencies: joint consensus statement on management of thyroid storm (ETA/BTA/SfE). Eur Thyroid J 2026 · Kopp PA et al. Approach to the patient with thyroid storm. J Clin Endocrinol Metab 2026 (summarizes 2016 ATA and JTA/JES guidance) · Ross DS et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis. Thyroid 2016;26:1343–1421 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).