Life-threatening hyperthyroidism with multisystem decompensation; mortality 10-30%.
Also known as: thyroid storm, thyrotoxic crisis, thyrotoxic storm
Overview
Severe, life-threatening exacerbation of thyrotoxicosis characterized by hyperpyrexia, marked tachycardia, CNS dysfunction, and multi-organ decompensation. Clinical diagnosis (Burch-Wartofsky Point Scale) — do not wait for thyroid function tests to act.
Epidemiology
Uncommon (<10% of hospitalized thyrotoxic patients), but mortality 10-30%. Most cases occur in patients with known or unrecognized Graves disease or toxic nodular goiter. Often precipitated by an identifiable trigger.
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Question 1EndocrineMedium
A 38-year-old woman with poorly controlled Graves disease presents to the emergency department two days after stopping her methimazole because of nausea. She is confused and agitated. Temperature is 40.2°C (104.4°F), heart rate is 152/min and irregularly irregular, and blood pressure is 148/82 mm Hg. Examination shows drenching diaphoresis, a diffusely enlarged thyroid with a bruit, and bilateral exophthalmos. Her Burch-Wartofsky score is 95. Which of the following best supports the diagnosis?
ASuppressed TSH with normal free T4 and free T3
BElevated total T4 with normal free T4 and TSH
CSuppressed TSH with low free T4 and low free T3
DElevated TSH with high free T4 and free T3
ESuppressed TSH with high free T4 and free T3
Reveal answer & full explanation
Correct answer: E — Suppressed TSH with high free T4 and free T3
ASuppressed TSH with normal free T4 and free T3
BElevated total T4 with normal free T4 and TSH
CSuppressed TSH with low free T4 and low free T3
DElevated TSH with high free T4 and free T3
ESuppressed TSH with high free T4 and free T3✓
Why Suppressed TSH with high free T4 and free T3 is correct
Thyroid storm is a severe exacerbation of thyrotoxicosis; the underlying biochemistry is primary hyperthyroidism, so the pituitary suppresses TSH while free T4 and free T3 are elevated.
In Graves disease the gland autonomously overproduces hormone (TSH-receptor antibody driven), giving a suppressed TSH with high free hormone levels, the pattern that confirms the thyrotoxic state behind the crisis.
Per the American Thyroid Association, storm remains a CLINICAL diagnosis (Burch-Wartofsky Point Scale >=45 is highly suggestive); labs confirm thyrotoxicosis but treatment should never be delayed waiting for them.
Why the others are wrong
Elevated TSH with high free T4 and free T3: this is the pattern of a TSH-secreting pituitary adenoma or thyroid hormone resistance, a rare central cause, not the Graves-driven primary hyperthyroidism producing storm.
Suppressed TSH with low free T4 and low free T3: suppressed TSH with low free hormones reflects central hypothyroidism, the opposite metabolic state from a hypermetabolic crisis.
Elevated total T4 with normal free T4 and TSH: an isolated high total T4 with normal free T4 and normal TSH indicates increased thyroid-binding globulin (pregnancy, estrogen), a euthyroid lab artifact rather than true thyrotoxicosis.
Suppressed TSH with normal free T4 and free T3 — this is subclinical hyperthyroidism; the suppressed TSH is tempting, but normal free hormone levels cannot drive a hypermetabolic crisis, and storm arises from overt thyrotoxicosis with elevated free thyroid hormone levels.
Question 2EndocrineMedium
A 34-year-old woman with poorly controlled Graves disease who stopped her methimazole two weeks ago is brought to the emergency department after a febrile illness. She is agitated and disoriented. Temperature is 40.4°C (104.7°F), heart rate is 168/min and irregular, and blood pressure is 158/92 mm Hg. She has a diffuse goiter with a bruit, exophthalmos, and drenching diaphoresis. Free T4 and free T3 are markedly elevated and TSH is undetectable. The clinical picture is consistent with thyroid storm. Which of the following best explains her hyperpyrexia, tachyarrhythmia, and CNS hyperactivity?
ADirect thyroid hormone stimulation of hypothalamic heat centers
BThyroid hormone-induced surge in adrenal medullary catecholamine secretion
CThyroid hormone suppression of hepatic thyroxine-binding globulin synthesis
DIncreased adrenergic receptor sensitivity to circulating thyroid hormone
EReduced peripheral conversion of thyroxine to its inactive reverse T3 form
Reveal answer & full explanation
Correct answer: D — Increased adrenergic receptor sensitivity to circulating thyroid hormone
ADirect thyroid hormone stimulation of hypothalamic heat centers
BThyroid hormone-induced surge in adrenal medullary catecholamine secretion
CThyroid hormone suppression of hepatic thyroxine-binding globulin synthesis
DIncreased adrenergic receptor sensitivity to circulating thyroid hormone✓
EReduced peripheral conversion of thyroxine to its inactive reverse T3 form
Why Increased adrenergic receptor sensitivity to circulating thyroid hormone is correct
In thyroid storm an acute rise in free thyroid hormone is amplified by increased tissue responsiveness, including upregulated/sensitized beta-adrenergic receptors, producing a hypermetabolic crisis.
This heightened adrenergic activity drives the hyperpyrexia, marked sinus tachycardia and atrial fibrillation, and CNS hyperactivity, while a precipitating stressor (here infection plus thionamide discontinuation) tips the patient into decompensation.
It is also why beta-blockade with propranolol is first-line, because it blunts the adrenergic effects and, at high doses, slows peripheral T4-to-T3 conversion.
Why the others are wrong
Direct thyroid hormone stimulation of hypothalamic heat centers - thyroid hormone raises body temperature by increasing peripheral oxidative metabolism and obligatory thermogenesis, not by resetting a hypothalamic thermostat, and a set-point mechanism would not account for her atrial fibrillation or CNS hyperactivity.
Thyroid hormone suppression of hepatic thyroxine-binding globulin synthesis - shifts in binding-protein levels change total hormone measurements without changing free hormone or tissue effect, and her free T4 and free T3 are already markedly elevated, so altered TBG is not what is driving the crisis.
Reduced peripheral conversion of thyroxine to its inactive reverse T3 form - not the mechanism; storm reflects excess active T3 and heightened tissue responsiveness, not altered handling of metabolically inactive reverse T3.
Thyroid hormone-induced surge in adrenal medullary catecholamine secretion - the hyperadrenergic picture suggests excess catecholamines, but circulating catecholamine levels are normal or low in thyrotoxicosis; the sympathetic features reflect heightened tissue responsiveness, including upregulated beta-adrenergic receptors, rather than increased catecholamine secretion.
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Thyroid storm treatment sequence — order matters (iodine must follow thionamide by ≥1 hour).
Treatment
First-line
1. Beta-blocker — propranolol 60-80 mg PO q4h or 0.5-1 mg IV q15 min (also blocks T4→T3 conversion); esmolol drip if HF/asthma concern; goal HR <100
2. Thionamide (inhibits thyroid peroxidase, blocking new hormone synthesis) — propylthiouracil (PTU) 500-1000 mg LOAD then 250 mg q4h (PTU preferred in storm because it ALSO blocks peripheral T4→T3 conversion); methimazole 60-80 mg/day acceptable alternative
3. Iodine — given AT LEAST 1 hour AFTER thionamide (to prevent fueling synthesis): SSKI 5 drops PO q6h or Lugol's solution 4-8 drops q6h; inorganic iodide blocks release of preformed hormone (high-dose iodide also transiently inhibits organification = Wolff-Chaikoff effect)
4. Glucocorticoid — hydrocortisone 100 mg IV q8h or dexamethasone 2 mg IV q6h (blocks T4→T3 conversion and treats relative adrenal insufficiency)
5. Supportive: aggressive cooling (acetaminophen, NOT aspirin which displaces T4 from binding proteins), IV fluids, electrolyte correction, treat precipitant, ICU admission
Second-line / adjunct
Plasmapheresis or therapeutic plasma exchange — removes circulating hormone in refractory cases
Emergent thyroidectomy after biochemical control
Cholestyramine to interrupt enterohepatic circulation of thyroid hormone
Avoid aspirin (displaces hormone); use acetaminophen for fever
ORDER MATTERS: beta-blocker first, then thionamide, then iodine AT LEAST 1 hour later (iodine before thionamide can fuel synthesis), then steroids.
PTU > methimazole in storm because PTU blocks peripheral T4→T3 conversion.
Acetaminophen for fever — never aspirin, which displaces thyroid hormone from binding proteins and worsens the crisis.
Burch-Wartofsky ≥45 = highly likely storm. Don't wait for TFTs to start treatment.
Look for the precipitant — infection is the most common trigger and must be identified and treated.
References
ATA 2016 — 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism — Thyroid Storm section (Ross et al., Thyroid 2016)
Burch & Wartofsky 1993 — Life-Threatening Thyrotoxicosis: Thyroid Storm (Burch & Wartofsky, Endocrinol Metab Clin North Am 1993)
JTA 2016 — Japan Thyroid Association Guidelines for the Management of Thyroid Storm (Satoh et al., Endocr J 2016)
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