Certified Emergency Nurse (CEN) Practice Test

In the context of myxedema coma, which is a severe form of hypothyroidism, the key indicator is a low heart rate. This condition is characterized by a significant deficiency of thyroid hormones, and one of the primary physiological responses to low levels of these hormones is bradycardia, or a slowed heart rate. Thyroid hormones play a crucial role in regulating metabolism, heart function, and overall energy levels, so their deficiency leads to a decreased metabolic rate, resulting in lower heart rate.

Other clinical features of myxedema coma can include hypotension, altered mental status, and hypothermia, but the bradycardia is particularly notable as it directly reflects the cardiovascular impact of low thyroid hormone levels. While low T3 and T4 levels are indeed present in hypothyroidism, they are more of a laboratory finding than an immediate clinical indicator in the setting of an acute crisis like myxedema coma.