Thyroid Function Test

You should get a thyroid function test if you have symptoms such as fatigue, unexplained weight gain or loss, hair loss, palpitations, anxiety, or cold or heat intolerance. It is also recommended during pregnancy, for infertility or irregular periods, during routine check-ups, and for monitoring thyroid medication.

No special preparation or fasting is required for a thyroid function test. Give your sample in the morning, and take your thyroid medicine after the sample unless your doctor advises otherwise. Stop biotin supplements 48–72 hours before the test, as biotin can interfere with results. Inform your doctor about pregnancy, oral contraceptives, or steroids.

No, fasting is not required for a thyroid function test. You can eat and drink normally before giving your sample. A morning sample is preferred, and you should take your thyroid medicine after the test unless your doctor advises otherwise. Stop biotin supplements 48–72 hours beforehand, as biotin can affect results.