salivary urea nitrogen

Urea, creatinine and uric acid in the plasma can enter the saliva through salivary gland cells, and the concentration in the saliva is related to the concentration in the plasma. Urea is hydrolyzed to NH4+ and CO2 by urease, and NH4+, NADH and α-ketoglutarate form CO2, glutamic acid and NAD+ under the action of glutamate dehydrogenase. Since NADH is oxidized to NAD+, the absorbance at 340 nm decreases, and its absorbance decrease is proportional to the urea concentration. Basic Information Specialist classification: oral examination classification: body fluid examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Reduced urea production and excess urea excretion. Normal value: Saliva urea nitrogen: 4.1-7.3mmol/L Above normal: Urea excretion disorder, excessive urea production, and gastrointestinal bleeding. negative: Positive: Reminder: The reagent cup, sample cup and reaction cup should be free of ammonia, clean, and free of acid and alkali pollution. It should be calibrated every time and tested with quality control serum. Normal value 4.1 to 7.3 mmol/L (11.4 to 20.4 mg/dl). Clinical significance 1. Raise (1) Urea excretion disorder 1 renal insufficiency (decreased glomerular function). 2 dehydration, edema, obstructive urinary tract disease. 3 diuretics. (2) Excessive urea production 1 high protein diet. 2 tissue necrosis (alienation hyperthyroidism) hunger strike, fever, infectious disease, diabetes, cancer, hyperthyroidism, surgery, the use of steroids. (3) Gastrointestinal bleeding. 2, lower (1) Reduced urea production 1 liver dysfunction (cirrhosis, severe hepatitis, poisoning). 2 low protein diet. 3 late pregnancy, infants and young children. 4 anabolic steroids, growth hormone. (2) Excessive urea excretion 1 more urine. 2 diabetes insipidus. Low results may be diseases: high gastrointestinal bleeding results may be diseases: liver cirrhosis, diabetes insipidus, kidney damage of hyperthyroidism, dehydration considerations 1. The most common problem with this method is the failure of the reagent or the contamination of the reaction system. The most unstable of the reagents are NADH and glutamate dehydrogenase. In the analysis process, attention should be paid to the following aspects: if plasma is used, fluorochemical compounds or NH4+ anticoagulants cannot be used. The former can inhibit urease activity, while the latter can participate in the reaction. 2. The absorbance of the reagent blank should be greater than 1.2A, otherwise the NADH is oxidized. For the same reagents and instruments, the F value should be relatively constant under the condition that the analysis conditions are constant, otherwise the reagent will be invalid. 3. Do not vibrate the reconstituted reagent to avoid deactivation of the enzyme. The reagent must be reconstituted with no ammonia. The reagent cup, sample cup and reaction cup should be free of ammonia, clean, and free of acid and alkali pollution. It should be calibrated each time and tested with quality control serum. Inspection process 1. Principle: Urea is hydrolyzed to NH4+ and CO2 by urease, and NH4+, NADH and α-ketoglutarate form CO2, glutamic acid and NAD+ under the action of glutamate dehydrogenase. Since NADH is oxidized to NAD+, the absorbance at 340 nm decreases, and its absorbance decrease is proportional to the urea concentration. 2. Reagents: At present, the kits produced by various manufacturers are not identical. A 0.1 mol/L (pH 7.5 ± 0.1) phosphate buffer solution was used for the buffer. Α-ketoglutaric acid 5mmol/L, NADH 3.5mmol/L, urease 15000U/L, glutamate dehydrogenase 2000U/L, ADP2mmol/L. 3. Specific operation: The reagent sample ratio is 70:1, 37 ° C, 340 nm, the lag time is 30 s, and the reading time is 30 s. The specific analysis conditions can be determined according to the specifications of the kit and the instrument, preferably every time. Not suitable for the crowd Those who do not have appropriate symptoms should not be tested. Adverse reactions and risks no.

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