Initial low-dose oral levothyroxine in a child with Down syndrome, myxedema, and cardiogenic shock.

Myxedema is extremely rare in children, and guidelines are lacking. We treated a 12-year-old girl with myxedema and cardiogenic shock with initial low dose (0.3-2.5 μg/kg body weight/day) of oral levothyroxine and intensive care. Oral administration may safely revert children's myxedema in a dosage resembling that for hypothyroidism.