Thyroid Response to Procedure-related Stress

Thyroid hormones (T4 and T3) increase the metabolic rate, promote thermoregulation and calorigenesis, and stimulate oxygen consumption; they also increase the number and affinity of β-adrenergic receptors in the myocardium and increase the sensitivity of the heart to epinephrine. During surgical stress, T3 concentration is inversely related to both circulating epinephrine and cortisol concentrations; consequently, perioperatively thyroid hormone production is reduced.1-3

Two prospective surveys over a 10-year period, involving 4,309 dentists, documented a total of 30,602 medical emergencies of which only four were diagnosed as thyroid storms.10 These cases most likely were the results of hormone-drug interaction; i.e., high circulating thyroid hormone levels as a result of undiagnosed or inadequately treated hyperthyroidism, or over treated hypothyroidism) augmented the physiologic effect of epinephrine in the local anesthetic.