In a blood test what is tsh?
Score: 4.6/5 (69 votes) The test, called a thyroid function test, looks at levels of thyroid-stimulating hormone (TSH) and thyroxine (T4) in the blood. Doctors may refer to this as "free" T4 (FT4). A high level of TSH and a low level of T4 in the blood could mean you have an underactive thyroid.What...