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Thyroid Storm

posted Mar 5, 2015, 5:02 PM by Kevin Hauck

Another Monte Minute, this time brought to you by PGY3 Janine Lebofsky, on Thyroid Storm! Based on one of our CRS from way back in October (the lateness is on my part!). 

Definition: life-threatening, rare, severe exacerbation of hyperthyroidism

Etiology: Usually precipitated by acute illness: surgery (especially thyroid surgery), stroke, radio iodine load in patient with partially treated or untreated hyperthyroidism, acute infection, trauma, childbirth.

Presentation:

-     Clinical manifestations are the same as those of untreated hyperthyroidism but tend to be more severe:

-    tachycardia to 140s (most commonly sinus tachycardia, but atrial fibrillation can occur and is more likely in patients over 50 years old)

-    hypotension

-    anxiety, tremors, psychosis, seizure, delirium

-    coma

-    fever

-    vomiting, diarrhea, jaundice

-    Physical exam findings can include moist and warm skin, goiter, ophthalmoplegia (only if Graves’ Disease present), lid lag, tremors, altered mental status.

Laboratory Values:

-    TSH, T3 and T4 reveal suppressed TSH and elevated T3 and free T4

-    Other lab abnormalities may include hypercalcemia (due to hemoconcentration and increased bone resorption), hyperglycemia (due to increased catecholamine activity inhibiting insulin release), abnormal liver function tests, leukocytosis or leukopenia

Diagnosis:

-    Diagnosis is a clinical diagnosis based on symptomatology, physical exam findings, thyroid function studies.

-    There are no validated clinical tools, but one known scoring system is called the “Burch Criteria” which assigns numerical value to different clinical manifestations of disease to help determine suspicion level of disease.

 Treatment

-    Same as for hyperthyroid but with higher doses of medication and more frequent administration

-    ICU care is indicated due to high mortality rate, as high as 30% even with treatment

-    Beta blocker: for symptom management (often propanolol is used, can be given intravenously when vital signs can be closely monitored, need to watch closely for hypotension/negative inotropic effects)

-    Thionamide (propylthiouracil/PTU or methimazole) used to block hormone synthesis. PTU is preferred for initial treatment over methimazole, because it blocks T4 to T3 conversion (methimazole does not). However, methimazole should be used for long-term treatment as it has a longer duration of action than PTU and is less hepatotoxic. Neither PTU nor methimazole acts to prevent release of already formed thyroid hormone.

-    Iodine solution given to block release of T3 and T4. Give iodine at least 1 hour after thionamide so that iodine cannot be used as substrate to make more thyroid hormone.

-    Iodinated radiocontrast agent given to block conversion of T4 to T3 and to block thyroid hormone release.

-    Glucocorticoids used to reduce T4 to T3 conversion, for vasomotor stability, and to treat potential associated adrenal insufficiency

 Long-term Treatment: Once patient recovers from thyroid storm, iodine can be discontinued and glucocorticoids tapered. Beta blockers can be decreased as tolerated. As discussed above, if PTU was used, treatment should be transitioned to methimazole.  Definitive treatment depends on underlying etiology of thyroid storm. 

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