High Total T3 

High T3 levels with low TSH suggest hyperthyroidism, A low TSH with high T3 or T4 usually indicates an overactive thyroid. This pattern may be seen in conditions such as Graves’ disease or thyroiditis, where excess thyroid hormone is produced. 

Low Total T3 

A low T3 level with high TSH may support a diagnosis of hypothyroidism, although T3 is not routinely used in assessing underactive thyroid, with T4 and TSH being the primary markers. Low T3 may also occur in nonthyroidal illness