The T3 Total blood test will measure the complete amount of T3 found in the patient's blood, including the triiodothyroxine bound to carrier proteins as well as triiodothyroxine that circulates unbound. In a normal range blood test, the T4 number will be higher than the T3. However, if the person suffers from hyperthyroidism, the T3 is likely to be higher.
A T3 blood test is rarely performed alone and will almost always be performed in conjunction with other thyroid hormone tests. Your physician will likely order the T4 blood test and a TSH blood test as well with the T3. If the TSH and T4 come back out of the normal range, it indicates that the person has hypothyroidism or hyperthyroidism.
