What is this tsh=low supposed to mean?

May be hyperthyroid: If the TSH is below 0.1, and you are not on medication for the thyroid, then you are probably hyperthyroid (rarely a pituitary problem.) see an endocrinologist because this can lead to serious problems if not treated. If you are on medication and the TSH is low but above 0.1 and you feel good, you may have just received a slightly more potent batch of med.