Urea Examination Procedure              

1.Purpose of examination: ● Urea estimation from serum or plasma by Urease Method.

2.Responsibility and Authority:

• Calibration: Technician
• Quality Control: Technician
• Routine operation: Technician
• Overall Monitoring: Quality Manager

3.Sample Details:

• Type of Sample: Serum,Plasma
• Type of container and additives: Plain without any additives
• Patient Preparation: As per Primary Sample Collection Manual sample_collection_manual
• Stability: At Room temperature 18°–28°C (64°–82°F) stability ≤ 24 hours
• Handling and transport: As per Primary Sample collection manual
• Storage: 24 hours at 2-8° C

4.Required Equipment:

• Centrifuge, Auto-Pipette, Disposable Tips, Disposable sample cups, FullyAuto Chemistry Analyzer

5.Required reagents:

• R1. β-NADH 1.915 g/L
• R2.α-ketoglutaric acid 13.149 g/L

GLDH 60.000 KU/L urease 10.000 KU/L

6.Reagent Handling

• Remove any air bubbles present in the reagents with a new applicator stick, or allow the reagents to settle at the appropriate storage temperature to allow the bubbles to dissipate. To minimize volume depletion, do not use a transfer pipette to remove bubbles.

7.Reagent Storage and stability

Unopened reagent stable at 2-8°C until expiration date. The onboard System temperature reagent is stable for 25 days. Instability or deterioration should be suspected if there are precipitates, visible signs of leakage or contamination, turbidity, or if calibration or controls do not meet the appropriate criteria.

8.Calibration Procedure: Consolidated Chemistry Calibrators(CONCC) Frequency:

• Reagent lot change
• QC out of range
• After service or maintenance
• Replacement in any parts of Instrument

Procedure:

1. Start the equipment.WDI abbotte fully.docx
2. Calibrators are ready to use.
3. Put calibrator 15-20 minutes at room temperature
4. Prior to use, mix the contents by inverting the vial. Do not shake the vial to prevent foam formation.
5. Take a 150 µl calibrator solution to separate aliquot.
6. Go to the calibration and give the calibration order.
7. Verify calibration with at least two levels of controls
8. If control results fall outside acceptable ranges,root cause analysis or recalibration may be necessary.

9.Quality control Procedure:

• Name: Biorad Level 1 & 2
• Frequency: As per Quality Control Procedure

Procedure for Reconstitution of IQC

• Reconstitution of QC material with 5 ml Distilled water by using calibrated fixed volume pipette.
• Leave to stand for 30 min in the dark place.
• Swirl gently several times during the reconstitution period to ensure that the contents are completely dissolved.
• Prior to use, mix the contents by inverting the vial. Do not shake the vial as the information of foam should be avoided. Ensure that no lyophilized material remains un-reconstituted.
• Prepare aliquots of 150 µl from the reconstituted QC material.
• Store these aliquots at -15° C to -20° C.
• Prior to use, make sure that aliquots should be at room temperature for at least 15 min.

Procedure to run IQC

• Press Control order
• Select Assay /Panel, to be run.
• Select the control/s and its level/s
• Give Carrier Number and Position number
• Press F3 / Add order
• Put respected carrier in RSH rack
• Check IQC results, in case outliers call residents.

10.Principle of the procedure used for examinations: Urea in the sample is hydrolyzed by urease to ammonia and carbon dioxide. The second reaction, catalyzed by glutamate dehydrogenase (GLDH), converts ammonia and α-ketoglutarate to glutamate and water with the concurrent oxidation of reduced nicotinamide adenine dinucleotide (NADH) to nicotinamide adenine dinucleotide (NAD). Two moles of NADH are oxidized for each mole of urea present. The initial rate of decrease in absorbance at 340 nm is proportional to the urea concentration in the sample.

Sample Preparation:

• Required SampleVolume: 150 µl of the sample
• Temperature: 37°

Take 150-200µl of the sample from Primary tube to the secondary aliquot. Write the sample ID on the aliquot.

Procedure to run Patient sample

1. Press Patient order
2. Select Assay /Panel, to be run.
3. Give Carrier Number and Position number
4. Press F3 / Add order
5. Put respected carrier in RSH rack

11.Performance Characteristics:

• Linearity: 3 to 128 mg/dL

This assay is linear across the analytical measuring interval of 3 to 128 mg/dL for serum. Automated Dilution Protocol: When using the Automated Dilution Protocol, the system performs a dilution of the specimen and automatically corrects the concentration by multiplying the result by the appropriate dilution factor. Manual Dilution Procedure: Dilute the specimen with saline (0.85% to 0.90% NaCl). Enter the dilution factor in the Patient or Control order screen

• The limit of detection (LOD): 3 mg/dl
• The limit of quantification(LOQ): 3 mg/dL
• Unit: mg/dl

Normal and critical ranges:

12.Laboratory Clinical interpretation:

• Increases in urea nitrogen may be due to increased production or decreased excretion. Urea nitrogen is useful in assessing renal function, especially with serum creatinine.
• Urea nitrogen clearance and urea nitrogen/creatinine ratio in serum are useful clinically to assess glomerular filtration rate (GFR) and volume depletion. Urea nitrogen is used before, during and after dialysis treatment to quantify an individual’s urea clearance during a single dialysis.

13.Interference and cross reaction: The Following analytes were tested up to the levels indicated at Direct Bilirubin concentrations of 0.14mg/dl and 5.03 mg/dl, and found not to interfere:

1. No interference from Bilirubin up to 30 mg/dL
2. No interference from Hemoglobin up to 1,000 mg/dL
3. No interference from Intralipid up to 750 mg/dL

13.Potential source of variation:

Turn around time (TAT):

• Routine: 6.0 hours
• Urgent: 2.0 hours

Recording of observation:

• Software backup
• Machine raw data

14.Storage & Disposal of waste: Follow storage & discard procedure

15.Environmental & Safety control:

• Follow the universal work precautions.
• Do not use component beyond the expiration date.
• Do not mix materials from different kit lot numbers

16.Caution:

R1 contains Methylisothiazolone and sodium azide may cause allergic reaction. Contact with acid librate toxic gas.

17.Precautions: Wear protective gloves / protective clothing / eye protection Do not breathe mist / vapors / spray Contaminated work clothing should not be allowed out of workplace Wash hands thoroughly after handling Keep only in original container

18.Response IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water / shower.

R2 contains hydroxymethyl aminomethane and sodium azide may cause allergic reaction. Contact with acid librate toxic gas.

19References:

1. Talke H, Schubert GE.Kliniscat
2. Teitz NW editer clinical gide for laboratory tests (3rd edi)
3. US department of labor,Occupational safety and health administration.
4. Burtis CA,Ashwood ER,editors,Tietz Textbook of clinical chemistry.