Total Triiodothyronine (TT3)

3,5,3, triiodothyronine abbreviation (T3). Most of the T3 in serum is derived from the deiodination of peripheral tissues, accounting for about 1/2 to 1/3 of the daily T4 yield. About 10% to 38% of T3 is directly secreted from the thyroid gland. The daily yield of T3 is about 30 μg, the total amount of T3 extrathyroid cells is 40 μg, and the serum concentration has a half-life of 1 day. Most of the serum (99.5%) binds to the binding protein, 90% of which binds to TBG, the rest binds to albumin, and the amount of binding to TBPA is minimal. The biological activity of T3 is 5 to 10 times that of T4. Although the concentration of T3 in serum is 1/50 to 1/80 of T4, T3 accounts for about 65% of total thyroid metabolism. T4 is converted to T3 after entering the target cell to exert biological effects, so T3 is considered to be a more important thyroxine. Basic Information Specialist classification: growth and development check classification: endocrine examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Hypothyroidism (hypothyroidism). Normal value: Adult: 1.2-3.2nmol/L 1-5 years old: 1.54-4.00nmol/L 6-10 years old: 1.39-3.7nmol/L Newborn: 0.98-4.26nmol/L Above normal: 1TT3 is the most sensitive indicator for the diagnosis of hyperthyroidism (hyperthyroidism). TT3 can be 4 times higher than normal when hyperthyroidism. 2 At the same time, TT3 is a specific indicator for the diagnosis of T3 type hyperthyroidism. negative: Positive: Tips: Before the inspection, you must stop eating foods rich in iodine, such as kelp, seaweed, sea fish and shrimp, etc., depending on the amount of food, stop eating for 2-4 weeks. Normal value The serum TT3 value is related to age. The level of TT3 is higher than that of normal adults after birth. After age 5, it gradually decreases with age. The elderly TT3 is often lower than normal. Therefore, clinically, TT3 values ​​of different ages should be established to avoid misdiagnosis of normal infants and young children as hyperthyroidism, and the elderly are misdiagnosed as hypothyroidism. Adults are 1.54 to 3.08 nmol/L (100 to 200 ng/dl). Cord blood is 0.23 to 1.16 nmol/L (15 to 75 ng/dl). The newborn is 0.49~3.33nmol/L (32~216ng/dl). 1 to 5 years old, 1.62 to 4.1 nmol/L (105 to 269 ng/dl). 5 years old to 10 years old 1.45 ~ 3.71nmol / L (94 ~ 241ng / dl). 10 to 15 years old 1.28 to 3.28 nmol/L (83 to 213 ng/dl). The normal value of serum TT3 was different in each laboratory. Clinical significance 1, TT3 increased in: 1TT3 is the most sensitive indicator for the diagnosis of hyperthyroidism (hyperthyroidism). TT3 can be 4 times higher than normal when hyperthyroidism. 2 At the same time, TT3 is a specific indicator for the diagnosis of T3 type hyperthyroidism. 2, TT3 reduction is common in: hypothyroidism (hypothyroidism). 3, low T3 syndrome, although there is a reduction in T3, but no hypothyroidism, can be seen in pernicious anemia, acute myocardial infarction, cirrhosis, uremia and other serious illnesses and chronic wasting diseases. The result is low, the disease may be high: the result of hypothyroidism is high. Possible diseases: pregnancy with hyperthyroidism, thyroid-related eye disease, toxic diffuse goiter First, before the inspection, you must stop eating foods rich in iodine, such as kelp, seaweed, sea fish and shrimp, etc., depending on the amount of food, stop eating for 2 to 4 weeks. Second, the following drugs should be stopped before the examination, according to the dosage and time, stop taking 2 to 8 weeks. 1. Iodine-containing drugs, such as iodide, compound iodine solution, and iodine-containing tablets. 2, drugs that affect thyroid function, such as thyroid tablets, anti-thyroid drugs. 3. Some Chinese herbal medicines, such as seaweed, kelp, fritillary, burdock, and wood pass. Third, the patient should be fasted on the day of the examination. Inspection process Determination method 2 ml of venous blood, no anticoagulation, separation of serum for measurement. Not suitable for the crowd People with reduced hematopoietic function such as leukemia, various anemia, myelodysplastic syndrome, or people with thrombocytopenia should pay attention to blood draw, and should not take more or more blood. Adverse reactions and risks 1. After the blood is drawn, do not press the needle hole to avoid subcutaneous hematoma. If there is a small piece of bruise in the blood, it is slightly tender, please don't panic, you can do hot compress after 24 hours to promote the absorption of blood. The general small amount of congestion will gradually absorb in 3 to 5 days and the color will become lighter and return to normal. 2, after the blood draw symptoms of dizziness such as: dizziness, vertigo, fatigue, etc. should immediately lie flat, drink a small amount of sugar water, and then undergo a physical examination after the symptoms are relieved.