Medical Minute: Myxedema Coma

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December 7, 2014 by dailybolusoflr

By: Marrissa Baker, MD

·         Expression of severe hypothyroidism

·         Incidence of 0.22 per million people per year

·         Often precipitated by acute illness   (CVA, MI, infection)

·         Most commonly presents in elderly women with long history of hypothyroidism

·         Mortality rate as high as 25-60% even with treatment
Presentation

·         General: hypothermia

·         CV: bradycardia, blocks, prolonged QT, Torsades de pointes, cardiac shock, hypotension, cardiac tamponade, generalized edema, intravascular depletion

·         Respiratory: decreased respiratory drive progressing to respiratory failure, edema of tongue and vocal cords

·         Electrolyte and renal: hyponatremia (increased serum ADH and impaired diuresis), renal failure from underlying rhabdomyolysis

·         GI: paralytic ileus, GI bleeding

·         Heme: increased risk of coagulopathy and bleeding

·         Neurologic: mental status progresses from lethargy to mental status changes to coma, seizures

Diagnosis

·         Primary hypothyroidism: high TSH and low T4

·         Secondary hypothyroidism (due to hypothalamic or pituitary dysfunction): may have low-normal TSH and low T4
Treatment

·         Thyroid hormone replacement – optimal treatment is controversial because of rarity

·         T4 IV 200-500 mcg followed by 50-100 mcg daily

·         T3 IV 5-20 mcg followed by 2.5-10 mcg q8-12 hrs

·         Consider hydrocortisone for possible adrenal insufficiency and hypopituitarism in patients with secondary hypothyroidism

·         Supportive care for hypothermia, hyponatremia, hypotension, mechanical ventilation

·         Treatment of precipitating conditions
 

REFERENCES

1. Klubo-Gwiezdzinska J,Wartofsky L. Thyroid Emergencies. Med Clin North Am. 2012 Mar;96(2):385-403. doi: 10.1016/j.mcna.2012.01.015. Epub 2012 Feb 17.

2. Kwaku MP, Burman KD. Myxedema coma. J Intensive Care Med. 2007 Jul-Aug;22(4):224-31.

3. Uptodate: myxedema coma

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