Emergency medicine clinics of North America
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Emerg. Med. Clin. North Am. · Nov 1989
ReviewThyroid disease in the emergency department. Thyroid function tests and hypothyroidism and myxedema coma.
The recognition of hypothyroidism may not always be easy in the emergency department setting. Laboratory evaluations of thyroid function are not usually performed on a 24-hour basis, and therefore the emergency physician, although suspecting the presence of hypothyroidism, may be unable to confirm the diagnosis while the patient is in the Emergency Department. ⋯ Myxedema coma is potentially fatal and must be recognized and treated emergently, usually prior to laboratory confirmation. Ventilatory support and thyroid hormone replacement are the two most important therapeutic maneuvers in the treatment of myxedema coma.
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Thyrotoxicosis and thyroid storm are disease states that result from thyroid hormone-induced hypermetabolism. The excess thyroid hormone is released from the thyroid gland as a result of excess thyroid hormone production, or by processes that disrupt the follicular structure of the gland with subsequent release of stored hormone. True hyperthyroidism results from increased synthesis and release of thyroid hormone and can be distinguished from other causes of thyrotoxicosis by the thyroid 131I uptake. ⋯ Thyroid storm may lead to irreversible cardiovascular collapse and death if proper treatment is not initiated in the Emergency Department. Specific therapy of hyperthyroidism follows several strategies, including inhibition of hormone synthesis and release, inhibition of peripheral conversion of T4 to T3, and blocking of the systemic effects of excess thyroid hormone. Treatments directed at these ends may be initiated rapidly in the emergency setting.
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Although relatively common, aberrations in divalent cation homeostasis may be overlooked in Emergency Department patients. The intracellular concentration of ionized calcium is the major regulator of cellular function. Patients may present with signs and symptoms of deranged calcium homeostasis that range from the mild and nonspecific to the truly life threatening. ⋯ Severe hypermagnesemia is rather uncommonly encountered in the Emergency Department. The magnesium ion is an effective calcium channel blocker, and patients with severe hypermagnesemia develop profound cardiovascular and neuromuscular dysfunction as a result. In pharmacologic doses, magnesium's unique calcium channel antagonism may be clinically useful, and there is growing interest in its potential use as an antiarrhythmic, anticonvulsant, and smooth muscle relaxant.