Triiodothyronine inhibition test

After taking exogenous T3 in normal people, the T3 concentration in the blood is increased. Negative feedback can inhibit the secretion of TSH in the anterior pituitary, and the 131I rate of thyroid is significantly reduced. Diffuse goiter with hyperthyroidism, due to the presence of long-acting thyroid stimulants (LATS) and long-acting thyroid stimulant protectants in the blood, can stimulate the thyroid to cause an increase in 131I, and is not inhibited by T3. The thyroid absorbing 131 iodine function test sometimes overlaps with the values ​​of normal people and hyperthyroidism, which affects the diagnosis of the disease. The triiodothyronine inhibition test method is used for differential diagnosis of patients with high iodine intake rate. The method was to take 60-100 μg of sodium triiodothyronine orally for 3 days for a total of 6 days on the 1st, and repeat the radioactive isotope iodine test. Basic Information Specialist classification: growth and development check classification: endocrine examination Applicable gender: whether men and women apply fasting: fasting Tips: Old age, patients with cardiovascular disease, myocardial ischemia or diabetes should be carefully considered before doing this test. Normal value Normal people absorb 131 iodine rate by more than 50%. Clinical significance The 131I uptake rate in patients with diffuse goiter with hyperthyroidism and simple goiter is increased. However, the 131I uptake rate of the former was not inhibited after taking T3, and the inhibition rate was <50131i="">50%. Patients with simple goiter with a significant goiter may not be able to inhibit the 131I uptake rate by taking T360μg per day. It should be doubled to 120μg per day to be inhibited. The T3 inhibition test was not inhibited in patients with invasive exophthalmos, and the 131I uptake rate after T3 was inhibited in other eyes. T3 inhibits the release of TSH from the pituitary by a feedback mechanism, thereby reducing the thyroid 131I uptake rate. This test is mainly used for the diagnosis of atypical hyperthyroidism and T3 type hyperthyroidism. It can also be used as an indicator to judge whether it is easy to relapse after stopping treatment with anti-thyroid drugs. Precautions In the elderly, patients with cardiovascular disease, those with myocardial ischemia or diabetes should be carefully considered before doing this test. Inspection process Triiodothyronine inhibition test method: for differential diagnosis of patients with high iodine intake rate. The method was as follows: 60-100 μg of sodium triiodothyronine was orally administered on the 1st, and it was taken in 3 times for 6 days, and the radioactive isotope iodine iodine test was repeated. Not suitable for the crowd In the elderly, patients with cardiovascular disease, those with myocardial ischemia or diabetes should be carefully considered before doing this test. Adverse reactions and risks Generally not.