Thyroid diseases are prevalent, you must understand these test indicators!

Author: Liu Xiangyi, Professor of Beijing Tongren Hospital, Capital Medical University

Reviewer: Wu Xueyan, Chief Physician, Peking Union Medical College Hospital

As an important endocrine gland, the functional status of the thyroid gland directly affects the body's metabolic rate and overall health. In recent years, thyroid disease has become one of the more common endocrine diseases in clinical practice. Therefore, understanding the detection indicators of thyroid function and its clinical significance is of great significance for the early diagnosis and effective treatment of the disease.

Thyroid serological examination mainly includes three categories of indicators: thyroid-related hormones, autoantibodies and tumor markers. Thyroid-related hormones include total triiodothyronine (T3), total thyroxine (T4), free T3, free T4 and thyroid stimulating hormone (TSH). Among them, free T3 and free T4 are directly in the form of physiological effects, while TSH is secreted by the pituitary gland to regulate the synthesis and release of thyroid hormones. Changes in these indicators can accurately reflect the functional status of the thyroid gland and are the basis for evaluating thyroid function.

In addition to thyroid hormone levels, the detection of autoantibodies is equally important. Commonly used thyroid autoantibodies in clinical practice include anti-thyroglobulin antibodies (TgAb), anti-thyroid peroxidase antibodies (TPOAb), and thyroid stimulating hormone receptor antibodies (TRAb). The presence of these antibodies often indicates the possibility of autoimmune thyroid diseases, such as Hashimoto's disease or Graves' disease. By detecting these antibodies, doctors can better understand the patient's condition and provide a basis for formulating a reasonable treatment plan.

It should be emphasized that although the increase in thyroid autoantibodies indicates that the thyroid may have suffered an autoimmune attack, there is currently no particularly good drug that can turn the antibodies negative. Therefore, during the treatment process, the focus should be on regulating thyroid function. If antibodies are elevated and accompanied by abnormal changes in thyroid function, active treatment is required to ensure normal levels of thyroid function. At the same time, for patients with elevated antibodies but normal thyroid function, regular review and monitoring are also required to promptly detect and deal with potential risks.

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For patients suspected of having thyroid tumors, in addition to the above tests, tumor markers such as thyroglobulin (Tg), anti-thyroglobulin antibodies (TgAb), carcinoembryonic antigen (CEA) and calcitonin (CT) are also required. Thyroglobulin is a protein unique to thyroid cells, and abnormally elevated levels of it may indicate the risk of thyroid cancer. Carcinoembryonic antigen and calcitonin are mainly used to exclude or assist in the diagnosis of certain specific types of cancer, such as medullary carcinoma. It is worth noting that because the interaction between anti-thyroglobulin antibodies and thyroglobulin may cause detection interference and incorrect results, in actual operations, both are usually tested at the same time to reduce the possibility of misdiagnosis.

From the perspective of clinical application, laboratory tests occupy an irreplaceable position in the diagnosis of thyroid diseases. Compared with traditional imaging methods, such as ultrasound or CT, laboratory tests can reveal changes in thyroid function earlier, which helps to achieve early detection and intervention of the disease. In addition, thyroid function tests are also an important screening method for those unexplained symptoms caused by various reasons, such as palpitations, weight loss or weight gain. Especially for pregnant women, maintaining a good thyroid function is not only related to their own health, but also one of the key factors to ensure the normal development of the fetus.

According to different clinical needs, thyroid function test items can be divided into "three items", "five items" and "eight items". The so-called "three items" refer to free T3, free T4 and TSH. These three items are the most basic and sensitive thyroid function indicators and are suitable for preliminary screening. The "five items" add the detection of total T3 and total T4 on this basis, which can more comprehensively evaluate the overall level of thyroid hormones. The "eight items" cover all the above-mentioned thyroid hormone and autoantibody indicators, which are suitable for in-depth analysis of complex cases. Choosing an appropriate testing package can not only meet the personalized needs of different groups of people, but also effectively save medical resources and improve the efficiency of diagnosis and treatment.

Hyperthyroidism and hypothyroidism are two common thyroid diseases, and the changes in their typical indicators also have certain regularities. Patients with hyperthyroidism usually show symptoms such as irritability, increased metabolic rate, palpitations, hunger and weight loss. At this time, thyroid hormone indicators such as free T3, free T4, total T3, and total T4 usually increase, while TSH decreases. On the contrary, patients with hypothyroidism show symptoms such as decreased metabolic level, loss of appetite, and weight gain. At this time, thyroid hormone indicators such as free T3, free T4, total T3, and total T4 usually decrease, while TSH increases.

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It should be noted that in some cases, the test results of free T3, free T4, total T3, and total T4 may also follow the above rules, which may be due to central changes or drug effects. At this time, a comprehensive judgment needs to be made based on the patient's clinical manifestations and other test results.