High Total T4:
High Total T4 together with low TSH usually indicates hyperthyroidism, meaning the thyroid is overactive. A low TSH with high T4 suggests an overactive thyroid and should prompt further evaluation for causes such as Graves’ disease.
Low Total T4:
Low Total T4 with high TSH suggests hypothyroidism, where the thyroid is underactive. This pattern is typical of an underactive thyroid and may require treatment and ongoing monitoring.
