GENERAL HISTOLOGY

Detailed explanation-1: -A low level of TSH and high levels of T3 and/or T4 usually means you have an overactive thyroid. Doctors may refer to these measurements as “free” T3 and T4 (FT3 and FT4). What’s considered normal varies depending on things such as your age and the exact testing technique used by the laboratory.

Detailed explanation-2: -Another example is a syndrome called central hypothyroidism. In this case, your TSH may be low, but you’re considered to have hypothyroidism because of damage to the pituitary gland. In this example, the gland is not making enough TSH to adequately stimulate the thyroid gland to produce T3 and T4.

Detailed explanation-3: -If your results show high total T3 levels or high free T3 levels, it may mean you have hyperthyroidism. Low T3 levels may mean you have hypothyroidism, a condition in which your body doesn’t make enough thyroid hormone. T3 test results are often compared with T4 and TSH test results to help diagnose thyroid disease.