A nurse is reviewing the medical record of a client who has been on levothyroxine for several months. Which of the following findings indicates a therapeutic response to the medication?

A. Increase in hours of sleep per night: While improved sleep might occur with levothyroxine, it is not an indicator of therapeutic response. The key response is normalization of thyroid function. B. Decrease in level of thyroxine (T4): A decrease in T4 levels suggests inadequate thyroid hormone replacement. Levothyroxine should normalize T4 levels, so a decrease would indicate suboptimal treatment. C. Increase in weight: Weight gain is a symptom of hypothyroidism and is not a sign of a therapeutic response. Proper treatment with levothyroxine should help stabilize weight or prevent further gain. D. Decrease in level of thyroid stimulating hormone (TSH): A decrease in TSH indicates that the thyroid hormone levels are normalizing. Levothyroxine therapy should reduce TSH levels as the thyroid function improves.