What does it mean if free T4 is high but TSH is normal?

If free T4 is high but TSH is normal, it may indicate thyroid hormone resistance, a condition where the body's tissues are resistant to the effects of thyroid hormones. It could also be an early indicator of hyperthyroidism where TSH hasn’t yet responded to the elevated T4 levels. Certain medications or health conditions, such as estrogen therapy or pituitary dysfunction, can also cause this discrepancy. Further evaluation by your healthcare provider, including additional hormone tests or imaging studies, is necessary to determine the cause and appropriate treatment.