Increase: primary hypothyroidism, Hashimoto's disease with hypothyroidism, exogenous thyroid-stimulating hormone secreting tumors (lung, breast), subacute thyroiditis in the recovery period. Ingestion of lithium metal, potassium iodide, and thyroid stimulating hormone releasing hormone can increase thyroid stimulating hormone.
Decrease: pituitary hypothyroidism, hyperthyroidism caused by non-thyroid stimulating hormone tumors, and intake of aspirin, corticosteroids and intravenous heparin.
Increase: In the early or recurring period of hyperthyroidism, TT3 can increase when TT4 is not yet elevated, so TT3 is a sensitive indicator for the diagnosis of hyperthyroidism; T3 is significantly elevated in patients with T3 hyperthyroidism, and TT4 is normal; like TT4, TT3 is also affected by TBG and increase with the increase of TBG. All diseases, drugs or foods that can increase TBG can also increase T3; it is important to test T3 to estimate whether the hyperthyroidism is recurring after treatment.
Decrease: T3 decreases in patients with hypothyroidism, but it is not as obvious as T4. In severe hypothyroidism, TT3 and TT4 both decrease, but TT3 does not necessarily decrease in mild hypothyroidism. Therefore, it is more meaningful to test T4 than T3 when diagnosing mild hypothyroidism.
Increase: more common in hyperthyroidism, TSH-secreting tumors, overuse of thyroid hormone, primary biliary cirrhosis, subthyroiditis, increased thyroid binding globulin, prealbuminosis, and can also be seen in severe infections and cardiac insufficiency, liver disease, kidney disease, etc.
Decrease: seen in hypothyroidism, idiopathic mucinous edema, thyroid hypoplasia, chronic lymphocytic thyroiditis, Hashimoto’s disease, decreased thyroid binding globulin, low T3, T4 syndrome, secondary (pituitary ) Hypothyroidism, subthyroiditis or painless thyroiditis recovery period; In addition, during the treatment of hyperthyroidism, diabetic ketoacidosis, malignant tumors, heart failure, etc. TT4 can also decrease.
Basically it is the same as TT3, but more sensitive than TT3, and the test value is not affected by TBG; in patients with subclinical hyperthyroidism, the symptoms of hyperthyroidism are not obvious, and TT3 can be in the normal range, but FT3 has mostly increased.
Basically it is the same as TT4, but more sensitive than TT4, and the test value is not affected by TBG.
Increase: chronic lymphocytic thyroiditis, Graves disease, hypothyroidism
Increase: autoimmune thyroiditis, chronic lymphocytic thyroiditis, hypothyroidism, subacute thyroiditis, thyroid cancer, etc.