Elevated T3 and T4 levels and decreased TSH levels are most commonly due to primary hyperthyroidism and thyrotoxicosis, but normal pregnancy needs to be excluded. t3, T4 and TSH are indicators of thyroid function when blood is drawn. t3 and T4 are secreted by the pituitary gland and have the effect of accelerating the synthesis and release of thyroxine. t3 and T4 are secreted by the thyroid gland, namely triiodothyronine T3 and T4 are secreted by the thyroid gland, namely triiodothyronine and tetraiodothyronine, which are hormones synthesized by the thyroid gland. When the level of T3 and T4 in the body is elevated, it will negatively inhibit the secretion of TSH by the pituitary gland, causing the level of TSH to decrease, while TSH has the effect of promoting the synthesis and release of T3 and T4, which are mutually related as negative feedback inhibition. 1. Primary hyperthyroidism: When primary hyperthyroidism occurs, the thyroid gland’s own synthesized thyroxine is abnormally high, and there will be an increase in T3 and T4 levels and a decrease in TSH. T3 and T4 levels increase and TSH decreases. Symptoms of hyperthyroidism may occur, such as palpitations, hand tremors, fear of heat, excessive sweating, irritability, irritability, excessive eating, easy hunger, loose stools, etc. In addition to blood tests for thyroid function, thyroid hormone receptor antibodies can also be checked, which is a meaningful indicator to assist in determining hyperthyroidism, and ultrasound of the thyroid gland can be done, which will indicate enlarged thyroid gland and abundant blood flow. In addition, nuclear imaging of the thyroid gland can also be done, which can confirm the diagnosis of hyperthyroidism if it indicates diffuse enlargement of the thyroid gland and increased technetium uptake. 2. Thyrotoxicosis: If the test reveals normal thyroid hormone receptor antibodies, but the thyroid ultrasound reveals damage to the thyroid gland, no significant increase in blood flow and reduced iodine uptake rate of the thyroid gland, the damage may be caused by inflammation of the thyroid gland, resulting in thyrotoxicosis. If the thyroid hormone stored in the thyroid gland leaks out, there will be high T3 and T4 and low TSH. 3. Normal pregnancy: There is a condition that is not a disease state. In early pregnancy when the early pregnancy reaction is very obvious, there may be high T3 and T4 levels and low TSH levels on the test index due to changes in human chorionic gonadotropin and estrogen and progesterone. In the middle and later stages of pregnancy, the synthesis of thyroid binding globulin increases, and there may be a mild increase in T3 and T4 levels and a mild decrease in TSH. Both of these states are not true hyperthyroidism and are associated with changes in hormone levels during pregnancy. If you are diagnosed with hyperthyroidism, you should first take rest and stop smoking and drinking, avoid iodine-rich foods such as kelp and shrimp, and take oral medications such as methimazole under medical supervision. If long-term medication is ineffective and there are symptoms such as thyroid nodules and pressure, surgery should be performed.