Thyroid Hormones

Thyroglobulin (Tg) is a 660 ku glycoprotein secreted by the thyroid follicular epithelium. It consists of two polypeptide chains, each containing 2768 amino acids. Each Tg contains about 2 molecules of thyroxine (T4) and 0.5 molecules of triiodothyronine (T3), which are stored in the follicular cavity. Lysosomal hydrolysis of Tg surface T4 and T3 releases them into the blood, while a small amount of Tg is also released into the blood. Some Tg is secreted into the blood through thyroid lymphatic vessels. Tg in the blood circulation is cleared by macrophages in the liver. Tg is the most important protein that can quantitatively reflect thyroid function. Tg is a major self-antigen of the thyroid gland, and its level has certain significance for the diagnosis of thyroid diseases. Thyroglobulin (Tg) is a tumor marker for differentiated thyroid cancer (DTC). Measuring the content of serum Tg helps to predict prognosis and monitor treatment effects.

Insulin-like growth factor-binding protein-1 (IGFBP-1) is a 25kDa protein synthesized and secreted by the fetus or human liver cells and maternal decidua in the human body. IGFBP-1 is a protein that binds insulin-like growth factor (IGF) with high affinity and can regulate the biological utilization of IGF and regulate cell proliferation and differentiation. After pregnancy, the concentration of IGFBP-1 begins to rise. It is one of the most important proteins in amniotic fluid from mid-pregnancy to just before delivery. Premature rupture of fetal membrane (PROM) refers to the rupture of fetal membranes before labor, with an incidence rate of about 10%. PROM is the most common complication during the perinatal period and can cause serious adverse consequences for pregnant women, fetuses, and newborns. It can lead to an increase in premature birth rate, perinatal mortality rate, intrauterine infection rate, and puerperal infection rate. Therefore, early detection of PROM is particularly important. Currently, clinical methods for detecting PROM include mirror examination, pH paper detection, early pregnancy β-HCG paper detection, and HCG fluorescence polarization immunoassay (FPIA) detection. However, they all have low sensitivity and are relatively cumbersome processes that are particularly susceptible to interference from urine, semen, blood, etc., and fetal membrane rupture will inevitably cause significant amniotic fluid leakage, resulting in low accuracy and sensitivity. IGFBP-1 in amniotic fluid can flow into the cervicovaginal area through the rupture site when fetal membranes rupture. The concentration of IGFBP-1 in amniotic fluid is 100-1000 times higher than that in urine and blood. Even a small amount of leakage can be detected. Therefore, IGFBP-1 can be used as a sensitive marker for detecting PROM.

Anti-Muellerian hormone (AMH), also known as Muellerian-inhibiting factor (MIF), belongs to the transforming growth factor β superfamily and is a disulfide-linked polypeptide hormone. AMH is a homodimeric glycoprotein composed of two monomers with a molecular weight of 70kDa, which are connected by disulfide bonds. The activation of AMH requires hydrolysis to release the carboxy-terminal dimer, which has the biological activity of promoting the degradation of Muellerian ducts and inhibiting the growth and differentiation of certain tumors. AMH is only secreted by gonads. In women, its serum concentration may reflect the size of the follicle pool. It is a new marker for reflecting ovarian aging and ovarian reserve function. Polycystic ovary syndrome (PCOS) is a common endocrine metabolic disorder in women of childbearing age, with an incidence rate of 5%~10% in China. It is the most common cause of anovulatory infertility. The serum AMH level can accurately reflect the number of antral follicles and can be used as a tool for diagnosing PCOS and evaluating its therapeutic effect. It can also be used as a substitute for B-ultrasound diagnosis of PCOS.

Follicle-stimulating hormone (FSH) is a glycoprotein hormone synthesized and secreted by the pituitary gland. In women, the function of FSH is to promote follicular development and maturation, and to cooperate with luteinizing hormone (LH) to promote estrogen secretion and ovulation of mature follicles, participating in the formation of normal menstruation. Its production is controlled by hypothalamic gonadotropin-releasing hormone and is also regulated by feedback from ovarian estrogen (E2). FSH belongs to the content of endocrine detection. This hormone can promote follicular development and maturation, and promote ovulation. FSH detection is of great clinical significance for the treatment of infertility. If the FSH level is high, it indicates that the ovarian function of women is poor, and there may be diseases such as ovarian dysplasia, primary amenorrhea, pituitary precocious puberty, etc. If the FSH level is lower than normal, it may be suffering from polycystic ovary syndrome and other diseases.

Luteinizing hormone (LH), also known as luteinizing hormone, has a molecular weight of about 30,000. It is a glycoprotein gonadotropin secreted by pituitary cells and can promote cholesterol conversion into sex hormones in gonadal cells. For women, it works together with follicle-stimulating hormone (FSH) to promote follicular maturation, estrogen secretion, ovulation, and corpus luteum formation and maintenance. For men, luteinizing hormone promotes the synthesis and release of testosterone by Leydig cells.

Prolactin (PRL), also known as lactogenic hormone or lactotropin, is a protein hormone secreted by the acidophilic cells of the anterior pituitary gland. Prolactin (prolactin, PRL) is a polypeptide containing 199 amino acids and three disulfide bonds, with a molecular weight of 22,000. Its main function is to promote the development and growth of mammary glands, stimulate and maintain lactation, and stimulate the generation of follicular LH receptors. Increased prolactin levels: seen in hyperprolactinemia, pituitary tumors, breast tumors, non-functional tumors, Cushing’s syndrome, acromegaly, pituitary stalk tumors, hypothalamic tumors, granulomas, meningitis, Chiari-Fromel syndrome, renal failure, primary hypothyroidism combined with increased thyrotropin-releasing hormone (TRH), Nelson’s syndrome, adrenal insufficiency, ectopic growth of tumors (such as pituitary tumor lung metastasis), chest wall injury, surgery, trauma, herpes zoster, amenorrhea and galactorrhea syndrome. Decreased prolactin: pituitary dysfunction, Sheehan’s syndrome, isolated PRL secretion deficiency syndrome, primary infertility, polycystic ovary syndrome, dysfunctional uterine bleeding, breast cancer sub-total resection. The determination of PRL can be used as an important indicator for evaluating hypothalamic-pituitary function. It has special important value for the diagnosis of pituitary prolactinoma, hyperprolactinemia caused by various factors and hypothalamic-pituitary stalk diseases.

Estradiol (estradiol, E2) is an important estrogen secreted by mature follicles in the ovaries. It can promote and regulate the normal development of female organs and secondary sexual characteristics. It is a transdermal estrogen therapy that supplements the deficiency of 17-β-estradiol secreted by female ovaries, while avoiding side effects caused by oral administration (breast pain, weight gain, hypertension, gallstones and liver dysfunction, etc.).

Testosterone (Ts), also known as testosterone, testosteron or androsterone, is secreted by the testes of males or the ovaries of females. The adrenal glands also secrete a small amount of testosterone. Whether male or female, testosterone affects many body systems and functions, including hematopoiesis, calcium balance, bone mineralization, lipid metabolism, glucose metabolism and prostate growth. According to statistics, the amount of testosterone secreted by adult males is 20 times that secreted by adult females. Serum testosterone is the most important male hormone. It is an important hormone that promotes the development of male internal and external reproductive organs, maintains male sexual function and secondary sexual characteristics. Measuring serum testosterone is a common test for judging disorders of sex hormones.

17α-Hydroxyprogesterone (17α-OHP) is an endogenous progestogen produced by the adrenal cortex and gonads. 17α-OHP has a diurnal rhythm change consistent with cortisol. In adult women of reproductive age, 17α-OHP concentration varies with the menstrual cycle, with luteal phase higher than follicular phase. During pregnancy, the fetus, placenta and adrenal glands can produce large amounts of 17α-OHP. After 32 weeks of pregnancy, the concentration of 17α-OHP rises sharply until delivery, and 17α-OHP is also present in the umbilical cord blood of newborns. Patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency have significantly increased blood 17α-OH-P concentration, while the increase in 17α-OH-P is smaller when 11-hydroxylase is deficient. About 6% of adult hirsute women have varying degrees of 21-hydroxylase deficiency. In this type of late-onset deficiency cases, the concentration of 17P often exceeds the upper limit of follicular phase, which is 0.9 ng/mL. The determination of 17α-OH-P is also used to analyze common acne in men and women, male baldness and some unexplained infertility.

Folic acid, also known as vitamin B9, is a water-soluble vitamin with the molecular formula C19H19N7O6. It is named after its abundance in green leaves and is also called pteroylglutamic acid. There are several forms of folic acid in nature, and its precursor compound is composed of three components: pyrimidine, para-aminobenzoic acid and glutamic acid. Folic acid plays an important role in cell division and growth, protein synthesis and other substance synthesis. Lack of folic acid in the human body can cause megaloblastic anemia, fetal neural tube defects, physical weakness, irritability, psoriasis eczema and other skin lesions. These are the clinical significance of measuring folic acid. Green leafy vegetables, animal organs and other foods contain more folic acid, but folic acid is easily oxidized after high-temperature cooking, so the amount of folic acid ingested from food is also limited. Excessive folic acid in the body can cause Alzheimer’s disease in the elderly and increase the risk of breast cancer.

Corticosterone is an organic compound with the molecular formula C21H30O4. It belongs to the class of 21-carbon steroid hormones and is produced by the adrenal cortex. The normal content in the human body is 3.75~66.4 nmol/L. When its content increases, it may indicate the risk of aldosterone tumors, Cushing’s syndrome, adrenal cortex tumors and other risks.

Cortisol is a hormone produced by the adrenal cortex. It is called a stress hormone because the body needs cortisol to maintain normal physiological functions under stress, so it is also called a stress hormone. When cortisol levels rise, patients may experience abnormal blood pressure, moon face, Cushing’s syndrome. When cortisol levels are low, hormone levels, blood pressure levels and body temperature levels may decrease. Therefore, adrenal cortex hormones need to maintain normal levels.

Insulin-like growth factor, also known as insulin-like growth factor IGF, is structurally similar to insulin. Now known insulin-like growth factors include IGF-1 and IGF-2, IGF-1 is a low molecular polypeptide. Many tissues such as the kidney and brain can synthesize and secrete IGF-1, but it is mainly synthesized by the liver in the normal body. IGF-1, known as the growth hormone mediator, is a hormone naturally produced under the stimulation of growth hormone in the human body. When the pituitary gland secretes growth hormone into the blood circulation, growth hormone can promote the synthesis and secretion of IGF-1 in the liver within a few minutes. Most of the effects of growth hormone on the body occur through IGF-1. Therefore, the determination of IGF-1 can help to evaluate pituitary function.

Growth hormone is a peptide hormone secreted by adenohypophysial cells.Increased symptoms: pituitary GH tumor (acromegaly and gigantism), ectopic GH secretion syndrome, GH insensitivity dwarfism, malnutrition, renal failure, prolonged fasting, stress, hypoglycemia strenuous activity, etc. Reduced symptoms: pituitary dwarfism, panhypopituitarism, adrenal hypercorticosis, etc. it is necessary to get effective treatment in time when there is an anomaly,.

PTH measurement can help judge parathyroid function. 1. Elevation: (1) Plasma PTH was significantly higher than normal, and the increase of serum calcium concentration could not inhibit the secretion of parathyroid hormone, which may be primary hyperparathyroidism; (2)Ectopic hyperparathyroidism: Hormones may be secreted by other ectopic tumors outside the parathyroid gland. For example, PTH is increased in renal and bronchial cancer, but it is not affected by blood calcium concentration; (3) The plasma PTH level is normal or slightly high, if the patient has low blood calcium and high blood phosphorus at the same time, it can be considered as pseudoparathyroidism;(4)Third stage hyperparathyroidism: After long-term secondary hyperparathyroidism, spontaneous hyperparathyroidism may occur. 2. Decrease: ① idiopathic hypoparathyroidism and hypomagnesic hypoparathyroidism, which due to decreased secretion of PTH caused by hypocalcemia; ② It inhibits PTH secretion when being non-hyperthyroid hypercalcemia such as malignant tumors, sarcoidosis, vitamin D poisoning, hyperthyroidism and other hypercalcemia.