What is the SINGLE most likely mechanism that accounts for the symptoms of tremors and anxiety in a 27-year-old woman?

The symptoms of tremors and anxiety in the described case can be closely linked to an increased metabolic rate, such as that seen in hyperthyroidism or other conditions that elevate metabolic function. An increased metabolic rate can lead to heightened physiological responses that manifest as tremors, which are involuntary, rhythmic muscle contractions, and anxiety, a common psychological response to heightened states of alertness and metabolic stress.

In hyperthyroidism, for instance, an excess of thyroid hormones ramp up metabolism, increasing heart rate, causing tremors, inducing anxiety, and leading to symptoms like weight loss and intolerance to heat. These conditions result from the enhanced role thyroid hormones play in stimulating cellular metabolism throughout the body.

In contrast, a deficiency in thyroid hormone typically leads to reduced metabolic activity, which would more often cause symptoms such as fatigue, weight gain, and low energy rather than tremors and anxiety.

Increased levels of calcitonin, produced by the thyroid gland, primarily function to regulate calcium levels and does not have a significant direct role in anxiety or tremors. Similarly, while insulin resistance can contribute to metabolic issues, it does not typically present with the acute symptoms of tremors and anxiety directly linked to an increased metabolic state.

Thus, the most fitting explanation