Question

Which lab test is the most helpful test to confirm an abnormal TSH level?

1) T3 test
2) T4 test
3) Thyroid antibody test
4) Thyroid ultrasound

Answer 1

The T4 test is the most helpful to confirm an abnormal TSH level because T4 levels provide a clear indication of thyroid function in response to TSH.

Step-by-step explanation:

The most helpful test to confirm an abnormal Thyroid-Stimulating Hormone (TSH) level is a T4 test. TSH, a hormone produced by the anterior pituitary, controls the release of thyroid hormones triiodothyronine (T3) and thyroxine (T4) from the thyroid gland.

T4 is produced in greater amounts and is the precursor to the more active T3. Therefore, measuring the levels of T4 can provide an indication of thyroid function in response to TSH. A T3 test can be informative as well, particularly if hyperthyroidism is suspected since T3 is more potent. Other tests, such as the thyroid antibody test, could help identify autoimmune causes of thyroid abnormalities, while thyroid ultrasound is more focused on the structure of the thyroid gland rather than its function.