Thyroid emergencies are rare life-threatening endocrine conditions resulting from either decompensated
thyrotoxicosis (
thyroid storm) or severe
thyroid hormone deficiency (
myxedema coma). Both conditions develop out of a long-standing undiagnosed or untreated hyper- or
hypothyroidism, respectively, precipitated by an acute stress-associated event, such as
infection,
trauma, or surgery. Cardinal features of
thyroid storm are myasthenia, cardiovascular symptoms, in particular
tachycardia, as well as
hyperthermia and central nervous system dysfunction. The diagnosis is made based on clinical criteria only as
thyroid hormone measurements do not differentiate between
thyroid storm and uncomplicated
hyperthyroidism. In addition to
critical care measures
therapy focusses on inhibition of
thyroid hormone synthesis and secretion (
antithyroid drugs,
perchlorate,
Lugol's solution,
cholestyramine,
thyroidectomy) as well as inhibition of
thyroid hormone effects in the periphery (β-blocker,
glucocorticoids).Cardinal symptoms of
myxedema coma are
hypothermia, decreased mental status, and
hypoventilation with risk of
pneumonia and
hyponatremia. The diagnosis is also purely based on clinical criteria as measurements of
thyroid hormone levels do not differ between uncomplicated severe
hypothyroidism and
myxedema coma. In addition to substitution of
thyroid hormones and
glucocorticoids,
therapy focusses on
critical care measures to treat
hypoventilation and
hypercapnia, correction of
hyponatremia and
hypothermia.Survival of both thyroid emergencies can only be optimized by early diagnosis based on clinical criteria and prompt initiation of multimodal
therapy including supportive measures and treatment of the precipitating event.