The TSH stimulates the thyroid in part by causing a higher rate of cell growth. Too much cell growth is a bad thing if the thyroid has a goiter, nodules, calcifications or if there are any lingering thyroid cancer cells. The approach to intentionally lower the TSH is called TSH suppression and those on thyroid medication are given slightly higher doses to achieve a lower TSH. However, if the TSH levels are too low, other side effects like damage to the heart and bones might outweigh any possible benefits. Note that there is some controversy about the net benefit of TSH suppression for benign nodules. Ref caref nodule
