What does it mean if T3 levels are high but T4 and TSH are normal?

High T3 levels with normal T4 and TSH can indicate T3 toxicosis, a form of hyperthyroidism where the thyroid primarily overproduces T3. This condition may cause typical hyperthyroid symptoms like rapid heartbeat, nervousness, and weight loss, but without elevated T4 levels. T3 toxicosis can occur in conditions like Graves’ disease. Your healthcare provider may order further tests to confirm the cause and determine the best treatment plan, which could include anti-thyroid medications or radioactive iodine therapy.