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===Block New Hormone Synthesis===
===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
'''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
<br>''Propylthiouracil (PTU) is prefered over methimazole because it will also bock T4->T3 conversion
#'''PTU''' 600-1000 mg PO or PR followed by 200-250mg q4hr  
#'''PTU''' 600-1000 mg PO or PR followed by 200-250mg q4hr  
#*Note black box warning of hepatotoxicity so check LFTs prior
#*Note black box warning of hepatotoxicity so check LFTs prior

Revisión del 23:47 20 feb 2015

Background

  • Mortality
    • Without treatment: 80-100%
    • With treatment: 15-50%

Precipitants

  • Infection
  • Trauma
  • Surgery
  • DKA
  • Withdrawal of thyroid medication
  • Iodine administration
  • MI
  • CVA
  • PE

Diagnosis

  1. Classic Triad:
    1. Hyperthermia
    2. Tachycardia
    3. AMS
      1. Agitation, confusion, delirium stupor, coma, seizure
  2. May also have:
    1. CHF
    2. Palpitations
    3. Dyspnea
    4. Increased pulse pressure
    5. A-fib

Burch & Wartofsky Diagnostic Criteria

I. Thermoregulatory dysfunction (Temperature)

Temp Points
99-99.9 5
100-100.9 10
101-101.9 15
102-102.9 20
103-103.9 25
104.0 30


II. Central nervous system effects

Mild (Agitation) 10pts
Moderate (delirium, psychosis, extreme lethargy) 20pts
Severe (seizure, coma) 30pts

III. Gastrointestinal-hepatic dysfunction

Moderate (diarrhea, n/v, abd pain) 10pts
Severe (unexplained jaundice) 20pts

IV. Cardiovascular dysfunction (tachycardia)

99-109 5pts
110-119 10pts
120-129 15pts
130-139 20pts
140 25pts

V. Congestive Heart Failure

Mild (pedal edema) 5pts
Moderate (bibasilar rales) 10pts
Severe (pulm edema, A. fib) 15pts

VI. Precipitant history

Negative 0pts
Positive 10pts

Scoring

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

Differential Diagnosis

Work-Up

  • Chemistry
  • CBC
  • TSH/Free T3/T4
  • Cortisol level (rule-out concurrent adrenal insufficiency)
  • ECG
  • Rule-out infection:

Treatment[1]

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)
  3. Cardiac decompensation (CHF, A-fib)
    • Rate control, inotropes, diuretics as needed

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 1-3mg boluses q3hr OR
    • Contraindications are same as for other medical conditions (e.g. CHF)

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

  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

If contraindication or previous toxicity to thionamide therapy, then can consider:

  • 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.

Other Therapies

  1. Esmolol 250-500mcg/kg loading dose, then 50-100mcg/kg/min
    • B1 selective so can be used in pt with active CHF, asthma, etc.
  2. 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) or oral lugol solution
  3. Lithium carbonate[2]
    • 300mg q6hr
    • Consider if iodine allergic

Adrenal Insufficiency Treatment

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

Disposition

  • Admission to ICU

See Also

Sources

  1. ↑ American Thyroid Association Treatment Recomendations http://www.thyroid.org/thyroid-guidelines/hyperthyroidism/resultsh/
  2. ↑ Carroll R, Matfin G. Endocrine and metabolic emergencies: thyroid storm. Ther Adv Endocrinol Metab. 2010 Jun; 1(3): 139–145. Full Text
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