What diagnostic test is most likely to be ordered for a patient with symptoms of unplanned weight loss, fatigue, and a palpable neck mass?

The symptoms of unplanned weight loss, fatigue, and a palpable neck mass often point towards potential thyroid dysfunction, particularly hyperthyroidism or thyroid malignancy. In this context, thyroid function tests are specifically designed to assess the levels of thyroid hormones in the bloodstream, such as thyroxine (T4) and thyroid-stimulating hormone (TSH).

An elevated T4 level alongside a suppressed TSH can indicate hyperthyroidism, which could be responsible for the weight loss and fatigue. Additionally, changes in nerve function and muscle metabolism associated with abnormal thyroid function can contribute to the overall symptoms. Furthermore, a palpable neck mass may suggest an enlarged thyroid gland or a nodule, which can necessitate further evaluation through thyroid function tests to ascertain how the thyroid is functioning.

Other tests such as a complete blood count (CBC) could contribute important information about overall health or the presence of anemia, but they are not specifically targeted at diagnosing thyroid-related issues. Similarly, a glucose tolerance test is primarily used to assess diabetes risk and would not provide pertinent information regarding thyroid function. A lipid panel assesses cholesterol levels and other fats in the blood, which are also unrelated to the assessment of thyroid health.

Thus, ordering thyroid function tests directly addresses the potential underlying thyroid