Purpose of the Test
To determine the level of urea nitrogen in serum samples.
Principle
Urea in the sample is hydrolyzed by urease to produce ammonia and carbon dioxide. The ammonia produced then reacts with salicylate and hypochlorite in the presence of nitroprusside to form a colored indophenol complex. The intensity of the color formed is directly proportional to the urea concentration in the sample.
Equipments
1. Semi-autoanalyzer
2. Test tubes
3. Micropipettes
4. Spectrophotometer
5. Cuvettes
6. Urea Reagent (R1 > Enzyme reagent, R2 Color reagent)
Prepare Reagent 1 before using by adding buffer (If New Reagent)
Sample Type
Serum or plasma is acceptable for the Test
Procedure
1. in 3 clean dry tubes add reagents and sample as mentioned in the Table below
| Blank | Standard | Test | |
|---|---|---|---|
| Reagent 1 | 1000 μl | 1000 μl | 1000 μl |
| STD | – | 10 μl | – |
| Sample | – | – | 10 μl |
| Incubation | Incubate for 10 mins | Incubate for 10 mins | Incubate for 10 mins |
| Reagent 2 | 1000 μl | 1000 μl | 1000 μl |
| Incubation | Incubate for 10 mins | Incubate for 10 mins | Incubate for 10 mins |
Procedure
3. using the colorimeter or spectrophotometer read the absorbance against blank at filter wavelenght 580 nm
4. then do the calculations based on the following formula
Urea = Absorbance of test / Absorbance of standard x Conc of standard
The STD Conc is 50 mg/dl or may vary depending on the reagent brand.
Normal Range
Quality Control:
1. Run two levels of control with each batch of samples.
2. Results should fall within established confidence limits.
3. Review QC results and take corrective action if needed.
Warning :
1. Hemolysis causes falsely decreased results.
M. Sulieman
mohammad@mlsgaate.com
Check expiration of all urea test reagents. Inspect analyzer for errors before testing. Run two levels of QC. Calibrate if QC is out of range. Follow SOP carefully for urea testing.
تحقق من صلاحية جميع كواشف اختبار اليوريا. فحص المحلل للأخطاء قبل الاختبار. شغّل مستويين من التحكم النوعي. قم بالمعايرة إذا كان التحكم النوعي خارج النطاق. اتبع التعليمات بعناية لاختبار اليوريا.
