Question: when tsh is low and t4 is normal?
Answer: A low TSH with normal free T4 and T3 levels is consistent with subclinical hyperthyroidism. Some patients with nodular goiter and Graves' disease, particularly early in the disease course, will have predominant elevations in T3 due to increased conversion of T4 to T3 and a disproportionate increase in T3 secretion.