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This article is published under the authorization of the author, please do not reprint without permission
.
Thyroid disease is a common disease in the department of endocrinology, and if it is not diagnosed and treated in time, it can damage multiple organs and tissues throughout the body
.
In the process of diagnosis and treatment of thyroid diseases, various related laboratory tests are inseparable
.
So what are the commonly used laboratory tests for thyroid diseases? When we get an inspection report, how should we interpret the inspection results? The laboratory examination of thyroid disease is the most commonly used and most important examination in the treatment of thyroid disease, including the following: ➤Tyroid secretion indicators: TT3, TT4, FT3, FT4, calcitonin; ➤ Thyroid-stimulating hormone (TSH) and Thyroid-stimulating hormone releasing hormone (TRH) secretion indicators; ➤Biochemical and immune indicators of the thyroid: TG, TPO-Ab, TG-Ab, TR-Ab
.
Thyroid secretion indicators 1.
Thyroxine includes total triiodothyronine (TT3), total thyroid hormone (TT4), free triiodothyronine (FT3), and free thyroxine (FT4)
.
It is an important hormone secreted by the thyroid, which has many functions such as promoting nutrient metabolism, physical growth, brain development, and perfecting nerve and cardiovascular functions
.
The level of serum thyroxine index directly reflects the functional state of the thyroid
.
Clinical significance ➤Elevation: It means hyperthyroidism, which is seen in Gravse disease, early thyrotoxicosis of subthyroiditis, Hashimoto's hyperthyroidism and functional thyroid nodules, drug-induced hyperthyroidism (taking iodine-containing preparations, contraceptives, estrogen and taking thyroxine drugs Treatment of overdose, etc.
)
.
➤Reduction: seen in primary hypothyroidism and secondary hypothyroidism (after hyperthyroidism iodine 131 treatment, after thyroid surgery, pituitary hypothyroidism, drug-induced hypothyroidism, etc.
)
.
Among them, FT3 and FT4 are relatively stable and are not easily affected by other factors.
They are currently commonly used laboratory indicators for the diagnosis of hyperthyroidism and hypothyroidism
.
FT3 first increases in the early stage of hyperthyroidism or at the early stage of recurrence, which is of great significance for the diagnosis of hyperthyroidism, while FT4 also increases when hyperthyroidism, but first decreases during hypothyroidism, and is superior to FT3 in the diagnosis of hypothyroidism
.
TT4 determination can be used for the diagnosis of hyperthyroidism, primary and secondary hypothyroidism and the monitoring of TSH suppression therapy; the vast majority of TT3 in serum (99.
5%) binds to specific proteins in plasma, and only a few are in a free state (0.
5 %)
.
The change of TT3 concentration indicates abnormal thyroid function.
TT3 and TT4 often increase simultaneously in hyperthyroidism
.
But there are exceptions
.
Special circumstances ➤Only increase in TT3: including TT3 hyperthyroidism (more common in iodine-deficient areas), TT3 superior hyperthyroidism (that is, after drug treatment for hyperthyroidism, TT4 is already normal, but TT3 does not decrease or even increases.
This type of recurrence rate is high.
Surgical treatment), early hyperthyroidism or early recurrence of hyperthyroidism; ➤Only increase in TT4: including TT4 hyperthyroidism (related to eating too much iodine-containing food), a small number of elderly hyperthyroidism with only high TT4; ➤Reduction in TT4: seen in hypothyroidism
.
Therefore, TT3 and TT4 values are often measured at the same time in clinical practice
.
2.
Calcitonin (CT) is a linear polypeptide hormone containing 32 amino acids secreted by thyroid parafollicular cells (also known as C cells).
The main physiological function of calcitonin is to regulate calcium ions in the blood.
Concentration, together with parathyroid hormone (PTH) and vitamin D and other factors to maintain the balance of calcium ions in the internal environment
.
The effect of calcitonin ➤The effect on bones: It can weaken the activity of osteoclasts and increase the activity of osteoblasts, thereby weakening the process of osteolysis, enhancing the process of osteogenic, and reducing the release of calcium salts from bone tissues, while increasing calcium salt deposition , Thus the blood calcium drops
.
Calcitonin can also inhibit the dissolution and transfer of bone salt, inhibit the decomposition of bone matrix, and increase the rate of bone turnover
.
➤Effects on the kidney: Calcitonin can inhibit the reabsorption of calcium, phosphorus, and sodium in the renal tubules, thereby increasing their excretion in urine, lowering their blood concentration, and causing hypocalcemia or hypophosphatemia, but It has little effect on potassium and chlorine
.
➤The effect on the gastrointestinal tract: It can inhibit the intestinal transport of calcium and the secretion of gastric acid, gastrin and insulin
.
Medullary Thyroid Carcinoma (MTC) originates from parafollicular cells of the thyroid, which can secrete a large amount of CT.
Therefore, CT is one of the most sensitive serological markers of MTC.
To determine the diagnosis, preoperative and postoperative evaluation and management of MTC by CT All have important meanings
.
Clinical significance ➤CT screening of patients with thyroid nodules can diagnose MTC early.
In the absence of stimulation, serum calcitonin >100 pg/ml may indicate the presence of MTC; ➤preoperative CT level and tumor malignancy Related, can help determine the scope of surgery; ➤Monitoring CT in the postoperative follow-up can be used to predict the risk of recurrence, early detection and treatment of metastatic lesions
.
TSH and TRH secretion indicators 1.
TSHTSH is produced in the pituitary gland and can promote the production of TT3, TT4, FT3, and FT4 by thyroid follicular cells
.
Clinically, thyroid hormone secretion indicators and thyroid-stimulating hormone secretion indicators are often checked together and comprehensively considered to reflect the secretion of the thyroid gland and guide the diagnosis and treatment of thyroid diseases
.
Clinical significance ➤TSH level is controlled by negative feedback of thyroxine
.
When thyroxine is high, TSH is low; when thyroxine is low, TSH is high
.
Therefore, TT3, TT4, FT3, and FT4 increase during hyperthyroidism, while TSH decreases, and the opposite is true during hypothyroidism
.
➤If only TSH increases and decreases clinically, TT3, TT4, FT3, FT4 are all normal, and it is often diagnosed as subclinical hypothyroidism or hyperthyroidism
.
➤But when serum free thyroid hormones (FT4, FT3) are higher than the normal range, but serum TSH is not inhibited, it indicates the possibility of TSH adenoma
.
2.
TRHTRH is synthesized and secreted by some nerve cells in the paraventricular nucleus of the hypothalamus
.
It is transported to the adenohypophysis through the pituitary portal system, which has the effect of promoting the secretion of TSH from the adenohypophysis, which in turn affects the secretion of thyroxine
.
Clinical significance ➤Elevated: more common in primary hypothyroidism, Sheehan's syndrome, anterior pituitary hypofunction, application of norepinephrine, dopamine, antithyroid drugs, cold response, etc.
; ➤Decreased: seen in hyperthyroidism , hypothalamic hypothyroidism
.
Thyroid biochemical and immunological indicators 1.
The normal reference value of thyroglobulin (TG) is 5-40μg/L
.
Clinical significance ➤Thyroid diseases (such as hyperthyroidism, toxic nodular goiter, subacute thyroiditis and chronic lymphocytic thyroiditis) can have elevated TG; ➤TG can judge the prognosis and monitor the treatment of thyroid cancer (DTC) The effect is of great significance: clinical follow-up of DTC patients found that the sensitivity of measuring TG content in diagnosing DTC recurrence or metastasis is 88% to 97%, and the specificity is 100%; high preoperative TG levels in thyroid cancer indicate that the tumor can produce TG.
Later TG can be used as a sensitive follow-up tumor marker
.
2.
Thyroid autoantibodies The three indicators of high-frequency examination in the Department of Endocrinology of Thyroid Autoantibodies are thyroid peroxidase antibody (TPO-Ab), thyroglobulin antibody (TG-Ab), and thyroid stimulating hormone receptor antibody (TR- Ab)
.
(1) The two antibodies, TPO-Ab and TG-Ab, are antibodies against the contents of thyroid cells, both of which are the hallmark antibodies of autoimmune thyroiditis, which may damage thyroid cells.
The increase in their levels indicates that the thyroid tissue is immune Active state of sexual inflammation
.
TPO-Ab and TG-Ab have basically the same clinical significance, but TPO-Ab is superior to TG-Ab in both sensitivity and specificity, and is the first choice for diagnosing thyroid autoimmune diseases (especially Hashimoto's thyroiditis) Indicators
.
In contrast, the specificity of TG-Ab is poor, and only an increase in TG-Ab is of little significance for diagnosis
.
In order to increase the positive detection rate, a combination of two kinds of antibodies is usually tested in clinic
.
Clinical significance ➤Etiological diagnosis: TPO-Ab and TG-Ab significantly increased is the main basis for the diagnosis of Hashimoto's thyroiditis
.
In addition, it can also be used for the differential diagnosis of autoimmune thyroid disease (AITD) and non-AITD, for example, primary hypothyroidism and secondary hypothyroidism.
The former is positive for TPO-Ab and TG-Ab, while the latter is Was negative
.
Patients with Graves disease hyperthyroidism may also have elevated TPO-Ab and TG-Ab, but the degree is mild or TPO-Ab is elevated and TG-Ab is normal
.
➤Prognostic judgment: It is generally believed that the increase of TP-OAb and TG-Ab indicates that the patient has an increased risk of hypothyroidism in the future
.
If pregnant women continue to be positive for TPO-Ab and TG-Ab, it indicates a higher risk of "postpartum thyroiditis" and "infant hypothyroidism", but it is not absolute
.
➤TG-Ab can also be used as a monitoring indicator for differentiated thyroid cancer (TDC): Under normal circumstances, the level of TG-Ab in patients with differentiated thyroid cancer will gradually decrease after radical resection and become negative within 1 to 4 years.
If TG -Ab level rises again, which often indicates tumor recurrence
.
Clinically, TG-Ab often integrates TSH and TG for risk and prognosis assessment and treatment response monitoring for thyroid cancer before and after surgery
.
(2) TR-Ab is an antibody against TSH receptor on the surface of thyroid cells, including two subtypes: thyroid stimulating antibody (TS-Ab) and thyroid inhibitory antibody (TB-Ab)
.
The former is related to the onset of autoimmune hyperthyroidism (Graves' disease), while the latter is related to the onset of autoimmune hypothyroidism (such as Hashimoto's thyroiditis)
.
At present, most hospitals only test TR-Ab, and cannot detect the two subtypes separately
.
TR-Ab tested clinically can be regarded as TS-Ab
.
Clinical significance ➤Diagnosing the cause of hyperthyroidism: The positive rate of TR-Ab in patients with Graves disease can reach more than 95%, while other causes of hyperthyroidism (such as subacute thyroiditis) are generally negative.
Therefore, TR-Ab is often used for Graves disease and other thyroid diseasesidentification
.
➤Guide the medication and judge the prognosis: TR-Ab is an important reference index for determining whether patients with Graves disease can stop the drug
.
A positive TR-Ab indicates that the body is in an immune active state, and a negative indicates that the body is in an immune remission state
.
After treatment for patients with Graves disease, if the thyroid function returns to normal, if the TR-Ab also turns negative, the possibility of recurrence after stopping the drug is small; if the TR-Ab continues to be positive after drug treatment, the possibility of recurring after stopping the drug is more likely Big
.
➤Help to predict neonatal hyperthyroidism: TR-Ab can pass through the placenta, stimulate the fetal thyroid gland, and cause transient hyperthyroidism in neonates (incidence rate 1 to 2%)
.
Therefore, testing TR-Ab for pregnant women with Graves disease can help predict neonatal hyperthyroidism and guide neonates whether it is necessary to take active screening or treatment measures
.
➤Contribute to the diagnosis of Graves ophthalmopathy with normal thyroid function: There are some patients with exophthalmia in clinical practice.
Although the thyroid function is normal, TR-Ab is strongly positive.
This condition can also be diagnosed as Graves ophthalmopathy
.
.
Thyroid disease is a common disease in the department of endocrinology, and if it is not diagnosed and treated in time, it can damage multiple organs and tissues throughout the body
.
In the process of diagnosis and treatment of thyroid diseases, various related laboratory tests are inseparable
.
So what are the commonly used laboratory tests for thyroid diseases? When we get an inspection report, how should we interpret the inspection results? The laboratory examination of thyroid disease is the most commonly used and most important examination in the treatment of thyroid disease, including the following: ➤Tyroid secretion indicators: TT3, TT4, FT3, FT4, calcitonin; ➤ Thyroid-stimulating hormone (TSH) and Thyroid-stimulating hormone releasing hormone (TRH) secretion indicators; ➤Biochemical and immune indicators of the thyroid: TG, TPO-Ab, TG-Ab, TR-Ab
.
Thyroid secretion indicators 1.
Thyroxine includes total triiodothyronine (TT3), total thyroid hormone (TT4), free triiodothyronine (FT3), and free thyroxine (FT4)
.
It is an important hormone secreted by the thyroid, which has many functions such as promoting nutrient metabolism, physical growth, brain development, and perfecting nerve and cardiovascular functions
.
The level of serum thyroxine index directly reflects the functional state of the thyroid
.
Clinical significance ➤Elevation: It means hyperthyroidism, which is seen in Gravse disease, early thyrotoxicosis of subthyroiditis, Hashimoto's hyperthyroidism and functional thyroid nodules, drug-induced hyperthyroidism (taking iodine-containing preparations, contraceptives, estrogen and taking thyroxine drugs Treatment of overdose, etc.
)
.
➤Reduction: seen in primary hypothyroidism and secondary hypothyroidism (after hyperthyroidism iodine 131 treatment, after thyroid surgery, pituitary hypothyroidism, drug-induced hypothyroidism, etc.
)
.
Among them, FT3 and FT4 are relatively stable and are not easily affected by other factors.
They are currently commonly used laboratory indicators for the diagnosis of hyperthyroidism and hypothyroidism
.
FT3 first increases in the early stage of hyperthyroidism or at the early stage of recurrence, which is of great significance for the diagnosis of hyperthyroidism, while FT4 also increases when hyperthyroidism, but first decreases during hypothyroidism, and is superior to FT3 in the diagnosis of hypothyroidism
.
TT4 determination can be used for the diagnosis of hyperthyroidism, primary and secondary hypothyroidism and the monitoring of TSH suppression therapy; the vast majority of TT3 in serum (99.
5%) binds to specific proteins in plasma, and only a few are in a free state (0.
5 %)
.
The change of TT3 concentration indicates abnormal thyroid function.
TT3 and TT4 often increase simultaneously in hyperthyroidism
.
But there are exceptions
.
Special circumstances ➤Only increase in TT3: including TT3 hyperthyroidism (more common in iodine-deficient areas), TT3 superior hyperthyroidism (that is, after drug treatment for hyperthyroidism, TT4 is already normal, but TT3 does not decrease or even increases.
This type of recurrence rate is high.
Surgical treatment), early hyperthyroidism or early recurrence of hyperthyroidism; ➤Only increase in TT4: including TT4 hyperthyroidism (related to eating too much iodine-containing food), a small number of elderly hyperthyroidism with only high TT4; ➤Reduction in TT4: seen in hypothyroidism
.
Therefore, TT3 and TT4 values are often measured at the same time in clinical practice
.
2.
Calcitonin (CT) is a linear polypeptide hormone containing 32 amino acids secreted by thyroid parafollicular cells (also known as C cells).
The main physiological function of calcitonin is to regulate calcium ions in the blood.
Concentration, together with parathyroid hormone (PTH) and vitamin D and other factors to maintain the balance of calcium ions in the internal environment
.
The effect of calcitonin ➤The effect on bones: It can weaken the activity of osteoclasts and increase the activity of osteoblasts, thereby weakening the process of osteolysis, enhancing the process of osteogenic, and reducing the release of calcium salts from bone tissues, while increasing calcium salt deposition , Thus the blood calcium drops
.
Calcitonin can also inhibit the dissolution and transfer of bone salt, inhibit the decomposition of bone matrix, and increase the rate of bone turnover
.
➤Effects on the kidney: Calcitonin can inhibit the reabsorption of calcium, phosphorus, and sodium in the renal tubules, thereby increasing their excretion in urine, lowering their blood concentration, and causing hypocalcemia or hypophosphatemia, but It has little effect on potassium and chlorine
.
➤The effect on the gastrointestinal tract: It can inhibit the intestinal transport of calcium and the secretion of gastric acid, gastrin and insulin
.
Medullary Thyroid Carcinoma (MTC) originates from parafollicular cells of the thyroid, which can secrete a large amount of CT.
Therefore, CT is one of the most sensitive serological markers of MTC.
To determine the diagnosis, preoperative and postoperative evaluation and management of MTC by CT All have important meanings
.
Clinical significance ➤CT screening of patients with thyroid nodules can diagnose MTC early.
In the absence of stimulation, serum calcitonin >100 pg/ml may indicate the presence of MTC; ➤preoperative CT level and tumor malignancy Related, can help determine the scope of surgery; ➤Monitoring CT in the postoperative follow-up can be used to predict the risk of recurrence, early detection and treatment of metastatic lesions
.
TSH and TRH secretion indicators 1.
TSHTSH is produced in the pituitary gland and can promote the production of TT3, TT4, FT3, and FT4 by thyroid follicular cells
.
Clinically, thyroid hormone secretion indicators and thyroid-stimulating hormone secretion indicators are often checked together and comprehensively considered to reflect the secretion of the thyroid gland and guide the diagnosis and treatment of thyroid diseases
.
Clinical significance ➤TSH level is controlled by negative feedback of thyroxine
.
When thyroxine is high, TSH is low; when thyroxine is low, TSH is high
.
Therefore, TT3, TT4, FT3, and FT4 increase during hyperthyroidism, while TSH decreases, and the opposite is true during hypothyroidism
.
➤If only TSH increases and decreases clinically, TT3, TT4, FT3, FT4 are all normal, and it is often diagnosed as subclinical hypothyroidism or hyperthyroidism
.
➤But when serum free thyroid hormones (FT4, FT3) are higher than the normal range, but serum TSH is not inhibited, it indicates the possibility of TSH adenoma
.
2.
TRHTRH is synthesized and secreted by some nerve cells in the paraventricular nucleus of the hypothalamus
.
It is transported to the adenohypophysis through the pituitary portal system, which has the effect of promoting the secretion of TSH from the adenohypophysis, which in turn affects the secretion of thyroxine
.
Clinical significance ➤Elevated: more common in primary hypothyroidism, Sheehan's syndrome, anterior pituitary hypofunction, application of norepinephrine, dopamine, antithyroid drugs, cold response, etc.
; ➤Decreased: seen in hyperthyroidism , hypothalamic hypothyroidism
.
Thyroid biochemical and immunological indicators 1.
The normal reference value of thyroglobulin (TG) is 5-40μg/L
.
Clinical significance ➤Thyroid diseases (such as hyperthyroidism, toxic nodular goiter, subacute thyroiditis and chronic lymphocytic thyroiditis) can have elevated TG; ➤TG can judge the prognosis and monitor the treatment of thyroid cancer (DTC) The effect is of great significance: clinical follow-up of DTC patients found that the sensitivity of measuring TG content in diagnosing DTC recurrence or metastasis is 88% to 97%, and the specificity is 100%; high preoperative TG levels in thyroid cancer indicate that the tumor can produce TG.
Later TG can be used as a sensitive follow-up tumor marker
.
2.
Thyroid autoantibodies The three indicators of high-frequency examination in the Department of Endocrinology of Thyroid Autoantibodies are thyroid peroxidase antibody (TPO-Ab), thyroglobulin antibody (TG-Ab), and thyroid stimulating hormone receptor antibody (TR- Ab)
.
(1) The two antibodies, TPO-Ab and TG-Ab, are antibodies against the contents of thyroid cells, both of which are the hallmark antibodies of autoimmune thyroiditis, which may damage thyroid cells.
The increase in their levels indicates that the thyroid tissue is immune Active state of sexual inflammation
.
TPO-Ab and TG-Ab have basically the same clinical significance, but TPO-Ab is superior to TG-Ab in both sensitivity and specificity, and is the first choice for diagnosing thyroid autoimmune diseases (especially Hashimoto's thyroiditis) Indicators
.
In contrast, the specificity of TG-Ab is poor, and only an increase in TG-Ab is of little significance for diagnosis
.
In order to increase the positive detection rate, a combination of two kinds of antibodies is usually tested in clinic
.
Clinical significance ➤Etiological diagnosis: TPO-Ab and TG-Ab significantly increased is the main basis for the diagnosis of Hashimoto's thyroiditis
.
In addition, it can also be used for the differential diagnosis of autoimmune thyroid disease (AITD) and non-AITD, for example, primary hypothyroidism and secondary hypothyroidism.
The former is positive for TPO-Ab and TG-Ab, while the latter is Was negative
.
Patients with Graves disease hyperthyroidism may also have elevated TPO-Ab and TG-Ab, but the degree is mild or TPO-Ab is elevated and TG-Ab is normal
.
➤Prognostic judgment: It is generally believed that the increase of TP-OAb and TG-Ab indicates that the patient has an increased risk of hypothyroidism in the future
.
If pregnant women continue to be positive for TPO-Ab and TG-Ab, it indicates a higher risk of "postpartum thyroiditis" and "infant hypothyroidism", but it is not absolute
.
➤TG-Ab can also be used as a monitoring indicator for differentiated thyroid cancer (TDC): Under normal circumstances, the level of TG-Ab in patients with differentiated thyroid cancer will gradually decrease after radical resection and become negative within 1 to 4 years.
If TG -Ab level rises again, which often indicates tumor recurrence
.
Clinically, TG-Ab often integrates TSH and TG for risk and prognosis assessment and treatment response monitoring for thyroid cancer before and after surgery
.
(2) TR-Ab is an antibody against TSH receptor on the surface of thyroid cells, including two subtypes: thyroid stimulating antibody (TS-Ab) and thyroid inhibitory antibody (TB-Ab)
.
The former is related to the onset of autoimmune hyperthyroidism (Graves' disease), while the latter is related to the onset of autoimmune hypothyroidism (such as Hashimoto's thyroiditis)
.
At present, most hospitals only test TR-Ab, and cannot detect the two subtypes separately
.
TR-Ab tested clinically can be regarded as TS-Ab
.
Clinical significance ➤Diagnosing the cause of hyperthyroidism: The positive rate of TR-Ab in patients with Graves disease can reach more than 95%, while other causes of hyperthyroidism (such as subacute thyroiditis) are generally negative.
Therefore, TR-Ab is often used for Graves disease and other thyroid diseasesidentification
.
➤Guide the medication and judge the prognosis: TR-Ab is an important reference index for determining whether patients with Graves disease can stop the drug
.
A positive TR-Ab indicates that the body is in an immune active state, and a negative indicates that the body is in an immune remission state
.
After treatment for patients with Graves disease, if the thyroid function returns to normal, if the TR-Ab also turns negative, the possibility of recurrence after stopping the drug is small; if the TR-Ab continues to be positive after drug treatment, the possibility of recurring after stopping the drug is more likely Big
.
➤Help to predict neonatal hyperthyroidism: TR-Ab can pass through the placenta, stimulate the fetal thyroid gland, and cause transient hyperthyroidism in neonates (incidence rate 1 to 2%)
.
Therefore, testing TR-Ab for pregnant women with Graves disease can help predict neonatal hyperthyroidism and guide neonates whether it is necessary to take active screening or treatment measures
.
➤Contribute to the diagnosis of Graves ophthalmopathy with normal thyroid function: There are some patients with exophthalmia in clinical practice.
Although the thyroid function is normal, TR-Ab is strongly positive.
This condition can also be diagnosed as Graves ophthalmopathy
.
