blood ammonia

Ammonia in the human body is produced by deamination of amino acids during protein metabolism, decomposition of glutamine by the kidneys, and action of bacteria in the intestines. Most of the ammonia synthesizes urea in the liver through the ornithine cycle. A part is used for the amination of keto acid, which synthesizes glutamine, and forms an ammonium salt in the kidney to be discharged from the urine. Blood ammonia plays an important role in the diagnosis and treatment of hepatic coma and hepatic encephalopathy. Urine ammonia determination is one of the indicators for assessing the imbalance of acid-base balance in the body. The methods for determination of blood ammonia include ion exchange resin method, direct method, electrode method and enzyme. The method, in which the enzymatic method is widely used, is widely used. Basic Information Specialist classification: Digestive examination classification: liver function test Applicable gender: whether men and women apply fasting: fasting Tips: The blood ammonia content is very small, to prevent the environment and the effects of ammonia in the various utensils used. Normal value The normal range is 18 to 72 μmol L. Clinical significance 1, increased in liver coma, severe hepatitis, liver cancer, shock, uremia, organophosphate poisoning, congenital hyperammonemia and transient hyperammonemia in infants. 2, reduced in low protein diet, anemia and so on. High results may be diseases: persistent vegetative state, hepatic encephalopathy precautions (1) Final concentration of each reagent component: phosphate 540 mmol/L, α-ketoglutaric acid 10 mmol/L, NAD-PH 120 μmol/L, ADP 0.5 mmol/L, GLDH 16 U/ml. (2) Enzymatic determination of plasma ammonia has the advantages of being specific, simple, and rapid, and can be applied to an automatic analyzer. Adenosine diphosphate (ADP) stabilizes GLDH and enhances the rate of reaction. NADPH as a coenzyme can shorten the reaction time compared with NADH, but the former is more expensive. (3) LDH, AST, etc. in plasma can also use NAD(P)H to produce endogenous consumption, which directly affects the results of plasma ammonia determination. The starter α-ketoglutaric acid is heated at 37 ° C for 10 min before NAD ( P) H endogenous consumption reaction time. (4) The accuracy of plasma ammonia determination depends to a large extent on whether the specimen collection meets the requirements. Anticoagulation with EDTA·Na2, venous blood collection and anticoagulant were mixed well, immediately placed in ice water, plasma was separated as soon as possible, and stored at 2 to 4 °C for storage, and analyzed within 2 to 3 hours; -20 °C for 24 hours, significant hemolysis Can not be used, because the concentration of ammonia in red blood cells is 2.8 times that of plasma. (5) The linear range is 0-150 μmol/L, and only 100 μmol/L standard application solution can be used in daily work. (6) If the measured value is out of the linear range, the plasma may be diluted with demineralized water and then reconstituted. (7) The blood ammonia content is very small, and it is necessary to prevent the influence of ammonia in the environment and various utensils used. (8) There is a plasma ammonia enzyme assay kit in China, please follow the instructions. For example, the kit of Zhongsheng Company uses triethanolamine buffer and NADPH as coenzyme. The endogenous consumption reaction of NADPH needs to be reacted for 20 min at room temperature. Inspection process Immediately after venous blood collection, the test is performed. The spectrophotometer used in the detection method is required to have a 37 ° C constant temperature colorimetric system and a wavelength of 340 nm. If an automatic analyzer is used, it can be designed according to the reaction conditions of this method, and the amount of sample and reagent is reduced proportionally. The operation was carried out in sequence, and mixed. When reading A10s at 10s, read A70s at 70s, and find △A of each tube, that is, △A=A10s-A70s. Not suitable for the crowd Generally no taboos. Adverse reactions and risks 1. Infection: Pay attention to aseptic operation when collecting blood, avoid contamination of water and other parts at the blood collection site to avoid local infection. 2, bleeding: after the blood is given a full compression time, especially coagulopathy, bleeding tendency, to avoid local subcutaneous oozing, bruising and swelling.