thyrotropin releasing hormone

Thyrotropin-releasing hormone (TRH) is a tripeptide secreted by the hypothalamus. Its physiological function is to release TSH stored in the anterior pituitary cells through a series of pathways, and increase the content of TSH and T3 and T4 in the blood. . Determination of plasma TRH while measuring TSH, T3, T4, so that you can understand the cause of thyroid disease, the lesion occurs in the thyroid or the pituitary or hypothalamus. TRH has been successfully synthesized and applied to the clinic. Basic Information Specialist classification: growth and development examination classification: blood examination Applicable gender: whether men and women apply fasting: not fasting Reminder: Due to the high technical requirements of TRH measurement, TRH stimulation test is often used in clinical practice, and TSH is replaced by TSH. Normal value (19.8 ± 3.1) pg / ml. Clinical significance (1) Increased TRH in primary hypothyroidism and increased TSH. In severe cases, the plasma TRH reached 3200 pg/ml. (2) Secondary hypothyroidism can be caused by pituitary and hypothalamic lesions. Pituitary hypothyroidism, such as the clinically common Shear syndrome, can also be elevated with elevated TRH. Hypothalamic hypothyroidism has a reduced plasma TRH secretion and a low function of the entire hypothalamic-pituitary-thyroid axis system. (3) TRH is normal or decreased when hyperthyroidism is hyperthyroidism, and may also be elevated. (4) In the early stage of subacute thyroiditis, the blood TRH is normal, and the late stage is elevated when the hypothyroidism is low. (5) Congenital individual TRH deficiency is clinically rare. (6) There are many changes in hormones in hypothalamic dysfunction, and sometimes there are changes similar to hypothalamic nails. High results may be diseases: hyperthyroidism, hypersecretion, resting lymphocytic thyroiditis, toxic diffuse goiter Due to the high technical requirements of TRH measurement, TRH stimulation test was used in clinical practice, and TSH was replaced by TSH. Inspection process The method is divided into three steps, namely antigen-antibody reaction, B and F separation, and radioactivity determination. (1) Reaction of antigen with antibody: The specimen (non-labeled antigen), labeled antigen and antiserum are sequentially dosed into a small test tube, and allowed to stand at room temperature (15 to 30 ° C) for 24 hours to fully compete for binding. (2) Separation of B and F: There are various separation techniques, and the precipitation method is commonly used. 1 second antibody precipitation method: also known as diabody method, after the test antigen specifically reacts with the first antibody, the corresponding second antibody is added, so that the formed antigen-first antibody-second antibody complex is co-precipitated. The labeled antigen B is separated from the free antigen F by centrifugation. This method is a specific precipitation, complete separation, low non-specific binding. However, the amount of the second antibody is large and the cost is high. In addition, the serum concentration and the presence or absence of anticoagulants can affect the results to some extent. 2 Polyethylene glycol (PEG) precipitation method: the protein is in an isoelectric point state, and the hydration layer is destroyed to cause protein precipitation. The advantage of this method is that PEG is convenient to prepare, inexpensive, and rapid to separate. The disadvantage is that there are many non-specific precipitates and the separation is incomplete. 3Second antibody-polyethylene glycol precipitation method: This method not only has the advantage of rapid precipitation of PEG method, but also maintains the effect of specific precipitation of second antibody, reduces the amount of second antibody, and reduces the concentration of PEG, so that non-specific precipitation Reduced material. 4 Activated carbon adsorption method: the free part of small molecules is adsorbed by the surface activity of activated carbon. For example, a layer of dextran is coated on the surface of the activated carbon to make a mesh having a certain pore diameter on the surface, thereby allowing small molecules of free antigen or hapten to escape and being adsorbed, while the macromolecular complex is excluded. After the antigen and the antibody are reacted, the dextran-activated carbon is added and allowed to stand for 5 to 10 minutes, so that the free antigen is adsorbed on the activated carbon particles, and the particles are precipitated by centrifugation, and the supernatant contains the labeled antigen. (3) Determination of radioactivity: After separation of B and F, the radioactivity can be measured. There are two types of measuring instruments: a liquid scintillation counter (measuring beta rays) and a crystal scintillation counter (measuring gamma rays). The unit of counting is the number of electrical pulses output by the detector in units of cpm (number of pulses/min). A standard curve is required for each measurement, and the different concentrations of the standard antigen are plotted on the abscissa, and the corresponding radioactivity measured is plotted on the ordinate. The radioactivity may be optionally B or F, and the calculated values ​​B/B+F, B/F or B/B0 may also be used. Specimens should be determined in duplicate, the average value is taken, and the corresponding antigen concentration is detected on the standard curve. Not suitable for the crowd No taboos. Adverse reactions and risks No complications.