Thyroid storm

Background

• Mortality
  • Without treatment: 80-100%
  • With treatment: 15-50%
• Difference between severe thyrotoxicosis and thyroid storm is clinical diagnosis
  • Must empirically treat before TFTs back from lab
  • Thyroid storm will present with Class Triad below and history of hyperthyroid and precipitant, at the very least

Precipitants

• Infection
• Trauma
• Recent thyroid manipulation (physical or surgical)
• Burns
• Surgery
• DKA
• Withdrawal of thyroid medication
• Iodine administration
• MI
• CVA
• PE
• Interferon treatment
• Molar Pregnancy
• Hypoglycemia
• Withdrawl of antithyroid treatment
• Exposure to iodine (or iodinated contrast)

Clinical Features

Classic Triad

• Hyperthermia
• Tachycardia
• AMS (agitation, confusion, delirium stupor, coma, seizure)
• May also have:
  • CHF
  • Palpitations
  • Dyspnea
  • Increased pulse pressure
  • A-fib

Differential Diagnosis

Altered mental status and fever

• Infectious
  • Sepsis
  • Meningitis
  • Encephalitis
  • Cerebral malaria
  • Brain abscess
• Other
  • Neuroleptic malignant syndrome
  • Serotonin syndrome
  • Malignant hyperthermia
  • Sympathomimetic toxicity (cocaine, amphetamine, ketamine)
  • Anticholinergic toxicity
  • Heat stroke
  • Delirium tremens
  • Hypothalamic stroke
  • Pheochromocytoma
  • Thyroid storm

Diagnosis

Work-Up

• Chemistry (Cr may be low or High Ca)
• CBC (may have Thrombocytopenia)
• TSH/Free T3/T4
• Cortisol level (rule-out concurrent adrenal insufficiency)
• ECG
• Rule-out infection:
  • CXR
  • Blood culture

Burch & Wartofsky Diagnostic Criteria

Category	Points
Thermoregulatory dysfunction (°F)
Tmax= 99-99.9	5
Tmax= 100-100.9	10
Tmax= 101-101.9	15
Tmax= 102-102.9	20
Tmax= 103-103.9	25
Tmax= 104	30
Central nervous system effects
Mild (Agitation)	10
Moderate (delirium, psychosis, extreme lethargy)	20
Severe (seizure, coma)	30
Gastrointestinal-hepatic dysfunction
Moderate (diarrhea, n/v, abd pain)	10
Severe (unexplained jaundice)	20
Cardiovascular dysfunction (tachycardia)
HR= 99-109	5
HR= 110-119	10
HR= 120-129	15
HR= 130-139	20
HR= 140	25
Congestive Heart Failure
Mild (pedal edema)	5
Moderate (bibasilar rales)	10
Severe (pulm edema, A. fib)	15
Precipitant history
Negative	0
Positive	10

Scoring

• >45 = Highly suggestive of thyroid storm
• 25-44 = Suggestive of impending storm
• <25 = Unlikely to represent storm

Treatment

Identify precipitant (i.e. med noncompliance, DKA, infection)

Supportive care

1. Fever
   • Cooling measures (ice packs & cooling blankets)
   • Acetaminophen (avoid aspirin or NSAIDS because they displace thyroid hormone from TBG)
2. Dehydration/hypoglycemia
   • D5NS (most pts have depleted glycogen stores)
   • Crackles in lungs are likely high output HF, NOT fluid overload
3. Cardiac decompensation (CHF, A-fib)
   • Rate control, inotropes, diuretics as needed (short acting always better)
4. Agitation
   • Benzodiazepines are the preferred agent

Decrease Peripheral Hormone Conversion

can use PO or IV Propranolol

1. Propranolol PO 60-80 q4hr (if pt can tolerate PO)
2. Propranolol IV 1-2mg over 10 min; if tolerates then 1-2mg boluses q15 minutes until HR <100
   • followed by drip at dose required for heart rate control (3-5mg/hr)
   • Relative contraindications are same as for other medical conditions (e.g. CHF, Reactive Airway Disease, see alternative therapies)
   • In addition to decreasing peripheral conversion there are propranolol will improve tremor, hyperpyrexia, and agitation

Block New Hormone Synthesis

Thionamides are the main class of medications which prevent new hormone synthesis by inhibiting the iodination of tyrosine residues by thyroid peroxidase (TPO) enzymes. Propylthiouracil (PTU) is prefered over methimazole because it will also bock T4->T3 conversion

• Below doses supported by AACE

1. PTU 600-1000 mg PO or PR followed by 200-250mg q4hr
   • Note black box warning of hepatotoxicity so check LFTs prior
   • Avoid in patients with significant liver disease; use methimazole instead
2. Methimazole 20-25mg q4hr
   • Longer acting than PTU
   • Should be avoided in pregnancy by classic teaching (Freely crosses placenta, birth defects)
3. Potassium iodide (SSKI)
   • Give 1hr after PTU to prevent increased hormone production (Jod-Basedow effect)
   • Block hormone release: (Wolff-Chaikoff effect) only after hormone synthesis is inhibited. Iodine concentration leads to transient decrease of T3/T4
   • 5 drops (0.25 mL or 250 mg) orally every 6 hours
   • Avoid potassium iodide if patient is on amiodarone
   • Can substitute radiocontrast dyes (Iopanoic acid, ipodate and iopanoate), PO Lugol solution, OR IV sodium iodide
4. Lithium carbonate
   • 300mg q6hr
   • Consider if iodine allergic
   • Lithium carbonate 300mg PO q8hr
   • Lithium inhibits thyroid hormone release from the gland and reduces iodination of tyrosine residues, but its use is complicated by the toxicity that can ensue.
5. Lugol’s Solution 8 drops PO q 6 (alternative iodine source)
6. Sodium Iodide 0.5 mg IV Q 12 hours (alternative iodine source)

Other Therapies

1. Esmolol 250-500mcg/kg loading dose, then 50-100mcg/kg/min
   • B1 selective so can be used with active CHF, asthma, etc; but does not perform other benefits of propranolol
2. Treatment of sympathetic Surge
   • Propranolol
3. Hyperthermia
   • Aggressive cooling should be avoided due to the possibility of worsening vasoconstriction

Adrenal Insufficiency Treatment

Often there may be associated adrenal insufficiency (also blocks T4>T3)

• Hydrocortisone 100-300mg IV bolus, followed by 100mg q8hr OR
• Dexamethasone 4mg IV q6hr

Disposition

• Admission to ICU

See Also

• Hyperthyroidism

External Links

• EMCrit - Thryoid Storm (149)