Indicators of thyroid function tests
Basal metabolic rate measurement: The function of thyroid hormones is indirectly understood by measuring the oxygen consumption of the body in the basal state. This method has many influencing factors and low specificity, and is now abandoned.
Thyroid iodine uptake rate of 131: Using the thyroid gland’s ability to concentrate iodine, patients are given a certain amount of radioactive iodine and the radioactivity of the thyroid region is measured at different times to understand the function of the thyroid gland by understanding its ability to absorb iodine. This method is influenced by the iodine in drugs and food and has been replaced by the sensitive and specific thyroid hormone assay, but sometimes it is still an effective method for checking thyroid function.
Thyroid hormone determination: The radioimmunoassay method has made thyroid hormone determination very easy. The ability to measure thyroid hormone levels by radioimmunoassay is now available nationwide, providing clinicians with a powerful tool for determining thyroid function. The current ultra-sensitive thyrotropin assay and free thyroid hormone assay have given us a more accurate method for determining thyroid function.
TT3: serum total triiodothyronine, a sensitive indicator for early GD, observation of efficacy during treatment and relapse after discontinuation of medication, and a specific indicator for the diagnosis of T3 hyperthyroidism. Normal value for adults: RIA method 1,8~2,9nmol/l (115~190ng/dl) ICMA method 0,7~2,1nmol (44,5~136ng/dl)
TT4: Determination of thyroid function is the most basic is a screening indicator. 65 to 156nmol/l (5 to 12ug/dl) for the RIA method 58, 1 to 154, 8nmol/l (4, 5 to 11, 9) for the ICMA method.
FT3: sensitivity and specificity are significantly higher than total T3 (TT3). Normal values in adults: RIA method 3-9 nmol/l (0,19-0,58ng/dl) ICMA method 2,1-5,4 nmol (0,14-0,35ng/dl)
FT4: sensitivity and specificity were significantly higher than total T4 (TT4). Normal values in adults: RIA method 9-25nmol/l (0, 7 to 1, 9ng/dl) ICMA method 9, 0 to 23, 9nmol (0, 7 to 1, 8ng/dl)
TSH: More rapid and significant than T3 and T4 to reflect changes in thyroid function. Normal value for adults: IRMA method (high sensitivity) 0, 4 ~ 3, 0 or 0, 6 ~ 4, 0 mu/l ICMA and TRIFMA are more sensitive than IRMA, called ultrasensitive TSH, normal range: 0, 5 ~ 5, 0 mu/l
Functional diagnosis: increased blood FT3 and FT4 (TT3, TT4) and decreased TSH (<0, 5mU/L) are consistent with hyperthyroidism; only increased FT3 or TT3 and normal FT4 and TT4 can be considered as T3 hyperthyroidism; only increased FT4 or TT4 and normal FT3 and TT3 are T4 hyperthyroidism; decreased blood TSH and normal FT3 and FT4 are consistent with subclinical type Hyperthyroidism.
Determination of thyroid autoantibodies.
Thyroid autoantibodies include thyroglobulin antibodies (TGA), thyroid microsomal antibodies (MCA), thyroid hormone antibodies, and thyroid hormone receptor antibodies. Thyroid hormone receptor antibodies are mainly used for etiological diagnosis and to determine whether hyperthyroidism is prone to recurrence after treatment, and are not routinely measured.
TGAb: If positive for a long time with a high titer, it indicates the possibility of progression to autoimmune hypothyroidism.
TMAb: Thyroid microsomal antibodies, now commonly referred to as “thyroid peroxidase antibodies – TPOA”.
Measurement of thyroglobulin (TG) and thyroid binding globulin (TBG).
Thyroglobulin is measured for the follow-up of papillary thyroid cancer and follicular thyroid cancer. Thyroid binding globulin is generally not measured in clinical practice.
Thyroid dynamic function tests.
These include the dry thyroid tablet suppression test, the T3 suppression test, and the TRH excitation test. The principle of these tests is based on the feedback relationship between the hypothalamus, pituitary, and thyroid axis, and the clinical significance of all 3 tests is the same. There is a large crossover between them, and generally only 1 of them needs to be selected. Ultrasensitive thyroid stimulating hormone assay can completely replace the above 3 tests.
Potassium perchlorate excretion test.
To find out whether there is an impairment of iodine organicization in the thyroid gland. It has diagnostic significance for congenital thyroid peroxidase disorders and is of secondary significance for the diagnosis of chronic thyroiditis.
Ultrasound examination of thyroid gland
(1) It can be used as a measurement of the size and volume of the thyroid gland.
(2) To identify whether the thyroid nodule is substantial or cystic, and to determine the location, size and depth of the mass. If the ultrasound shows that the mass contains fluid and the cyst wall is thin and smooth, the possibility of malignancy is low and can be treated with ultrasound-guided aspiration of the cystic fluid.
(3) Isolated nodules or multiple nodules can be detected and the size of the nodules can be measured.
(4) To assist in the identification of benign and malignant thyroid tumors, the presence or absence of calcification and the blood flow of the mass can be observed as a reference for the diagnosis of benign and malignant tumors, and those with dense calcification and abundant blood flow have the possibility of malignancy. For postoperative thyroid cancer patients, recurrent or metastatic lesions that cannot be retrieved can be detected.
Thyroid isotope scan
Also known as radionuclide imaging of the thyroid, it is most commonly used to identify the nature, number and size of thyroid nodules. It works by setting up the thyroid gland to take up a certain contrast agent (such as radioactive iodine or 99M Tc) and then using a gamma scanner camera to photograph the distribution of the contrast agent in the gland. For example, a nodule with dense contrast is called a “hot nodule”, which often indicates a benign high-functioning adenoma. In this order, there are “warm nodules”, “cool nodules” and “cold nodules”, and thyroid cancer is mostly “cold nodules”. The majority of thyroid cancers are “cold nodules”. In addition, thyroid scans can help physicians diagnose subacute thyroiditis or look for metastases of thyroid cancer.
CT thyroid examination
(1) It helps to diagnose thyroid adenoma.
(2) It can help to diagnose thyroid cancer and detect enlarged lymph nodes in the deep neck due to metastasis of thyroid cancer. Advanced thyroid cancer can metastasize to the cranial, pulmonary and skeletal systems, which can be easily detected by CT examination, thus providing valuable information for clinical treatment and prognosis assessment.
(3) Multiple endocrine neoplasm (MEN) type IIA, also known as Sipple syndrome, includes medullary thyroid carcinoma, pheochromocytoma and parathyroid adenoma or hyperplasia. Type IIB includes, in addition to medullary thyroid carcinoma and pheochromocytoma, multiple mucosal fibromas. For MEN IIA and IIB, CT examination can not only further confirm the clinical diagnosis, but also show the location, number and size of multiple endocrine tumors, which can provide valuable information for clinical treatment.
(4) CT examination can help detect multiple nodules in the thyroid gland. CT examination can be used to make a clear diagnosis of multinodular goiter in the neck extending into the thorax, and can differentiate it from other mediastinal tumors.
(5) Most cases of Graves’ disease are accompanied by hyperthyroidism, goiter and proptosis. In a few cases, there is no clinical manifestation of hyperthyroidism, but only proptosis, which is called ophthalmic Graves’ disease. In this case, CT examinations can not only differentiate the disease from other causes of proptosis, but can also lead to further clinical investigations, such as TSH excitation tests, which may reveal abnormalities.
Thyroid aspiration cytology
Thyroid aspiration is often used when certain thyroid disorders are difficult to detect despite multiple tests. It usually includes a puncture biopsy and a puncture cytology. In this method, a small needle is inserted into the lesion of the thyroid gland and a small number of cells are extracted, which are examined microscopically to understand the nature of the cells and make a diagnosis. This test is of great importance in the differential diagnosis of Hashimoto’s thyroiditis, subacute thyroiditis, and benign and malignant thyroid tumors. However, thyroid puncture can sometimes result in false positives or false negatives, because the accuracy of the diagnosis is closely related to the location of the sample.