Which symptom would indicate a potential thyroid storm?

A heart rate of 180 is indicative of a potential thyroid storm, also known as thyrotoxic crisis, which is a severe and life-threatening exacerbation of hyperthyroidism. During a thyroid storm, the body experiences an overwhelming release of thyroid hormones into the bloodstream, leading to a hypermetabolic state. This can cause a range of symptoms including an extremely elevated heart rate (tachycardia), which can surpass 180 beats per minute.

Typically, patients might also exhibit symptoms like fever, agitation, and profuse sweating, inflating the clinical picture of this condition. In this context, the high heart rate is a critical symptom that points to the increased metabolic activity associated with the storm, thereby allowing for early recognition and treatment.

Weight gain is contrary to the expected presentation of hyperthyroid conditions, where weight loss is more common. A low temperature contradicts the hallmark hyperthermia observed during thyroid storms, and a calm and stable mental state is not consistent with the agitation and confusion that often accompany this severe condition.