How and when to check thyroid functions in thyroid hypofunction?

In primary hypothyroidism, after the initial dose adjustment, which may require four to six months, we recommend annual clinical and biochemical assessment of thyroid function. The best biochemical parameters to watch are TSH and fT4. The frequency of monitoring the thyroid function is more in cases of hyperthyroidism. The chance of hypothyroidism after RAI or surgery is high, so close monitoring has to be done especially for the first year following therapy. Frequent monitoring is also required in pregnancy.