Anti-glomerular basement membrane antibody assay (AGBM)

The anti-glomerular basement membrane antibody is a network structure composed of a transparent layer inside and outside the glomerular capillaries and an intermediate dense layer, and is mainly composed of glycoprotein. The most common method for detecting GBM antibodies is the IIF method (indirect immunofluorescence) in which kidney tissue is used as an antigen. The fluorescence is characterized by typical petal-like, or speckled, granular staining at the glomerular basement membrane. False positive results can occur with the IIF method. An ELISA and radioimmunoassay using collagenase-digested crude GBM as an antigen is also available, and its sensitivity and specificity depend on the purity of the antigen. Clinically, it is commonly detected by indirect immunofluorescence. The principle of indirect immunofluorescence experiments is to label fluorescein on the corresponding antibody and directly react with the corresponding antigen. In the first step, an unknown unlabeled antibody (sample to be tested) is added to a known antigen sample, and incubated at 37 ° C for 30 min in a wet box to sufficiently bind the antigen antibody, followed by washing to remove unbound antibody. In the second step, a fluorescently labeled anti-globulin antibody or an anti-IgG, IgM antibody is added. If an antigen-antibody reaction occurs in the first step, the labeled anti-globulin antibody will further bind to the antigen-bound antibody, thereby identifying an unknown antibody. Basic Information Specialist classification: growth and development check classification: immunological examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: normal. Positive: Anti-GBM antibody-positive patients accounted for 5% of autoimmune nephritis, 80% of patients with glomerulonephritis and hemoptysis syndrome, and 20% of patients with menstrual glomerulonephritis A positive detection rate of 70% can also be detected in proliferative nephritis. Tips: After 8 pm on the day before the medical examination, you should start fasting for 12 hours, so as not to affect the test results. Normal value Indirect immunofluorescence, indirect hemagglutination was negative (or serum titer <4). Clinical significance Positive: Anti-GBM antibody-positive patients accounted for 5% of autoimmune nephritis, 80% of patients with glomerulonephritis and hemoptysis syndrome, and 20% of patients with menstrual glomerulonephritis A positive detection rate of 70% can also be detected in proliferative nephritis. Precautions First, the precautions before blood draw: 1, do not eat too greasy, high-protein food the day before the blood, to avoid heavy drinking. The alcohol content in the blood directly affects the test results. 2. After 8 pm on the day before the medical examination, you should start fasting for 12 hours to avoid affecting the test results. 3, should relax when taking blood, to avoid the contraction of blood vessels caused by fear, increase the difficulty of blood collection. Second, after blood draw should pay attention to: 1. After blood is drawn, local compression is required at the pinhole for 3-5 minutes to stop bleeding. Note: Do not rub, so as not to cause subcutaneous hematoma. 2, the pressing time should be sufficient. There is a difference in clotting time for each person, and some people need a little longer to clotting. Therefore, when the surface of the skin appears to be bleeding, the compression is stopped immediately, and the blood may be infiltrated into the skin due to incomplete hemostasis. Therefore, the compression time is longer to completely stop bleeding. If there is a tendency to bleed, the compression time should be extended. 3, after the blood draw symptoms of fainting such as: dizziness, vertigo, fatigue, etc. should immediately lie down, drink a small amount of syrup, and then undergo a physical examination after the symptoms are relieved. 4. If there is localized congestion, use a warm towel after 24 hours to promote absorption. 3. Please inform the doctor about the recent medication and special physiological changes before the test. Inspection process Same as indirect immunofluorescence. Not suitable for the crowd There are no taboos. Adverse reactions and risks There are no related complications and hazards.