The Creative Approach to Bioscience
Urea/BUN - LS SYMBOLS IN PRODUCT LABELLING
(Modified Urease-Berthlot Method) EC REP Authorised Representative Use by/Expiration Date
IVD For in-vitro diagnostic use CAUTION. Consult instructions
LOT Batch Code/Lot number for use
REF: 321 001 90 Test REF: 321 002 180 Test
REF Catalogue Number Manufactured by
R1 Buffer 1 x 90 ml R1 Buffer 2 x 90 ml Consult instructions for use (Xi) - Irritant
R2 Urease 1 x 1.5 ml R2 Urease 2 x 1.5 ml o
C
R3 Alkaline reagent 1 x 20 ml R3 Alkaline reagent 1 x 40 ml
o
C Temperature Limitation
Intended Use Deterioration
Spectrum Diagnostics colorimetric urea reagent is intended for the Do not use the reagent if it is turbid. Failure to recover control values
in-vitro quantitative, diagnostic determination of urea in human serum within the assigned range may be an indication of reagent
on both automated and manual systems. deterioration.
Background Specimen Collection and Preservation
Urea is the major end product of protein nitrogen metabolism. It is Serum
synthesized by the urea cycle in the liver and excreted through the No special preparation of the patient is required. Use nonhaemolyzed
kidneys. The circulating levels of urea depend upon protein intake, serum or plasma only.The only acceptable anticoagulants are heprin,
protein catabolism and kidney function. Elevated urea levels can EDTA and fluoride. Do not use ammonium heparin plasma.
occur due to renal impairment or in some diseases such as diabetes, Stability: 7 days at 15 –25oC ; 7 days at 2 – 8 oC;
infection, congestive heart failure and during different liver diseases. 1 year at -20 oC
Determination of blood urea nitrogen is the most widely used screening Urine
test for renal function together with serum creatinine. Urine samples are prediluted 1 : 50 with ammonium free water prior
to assay.
Method Stability: 2 days at 15 –25 oC ; 7 days at 2 – 8 oC;
1 month at -20 oC
Urease-colorimetric method.
System Parameters
Assay Principle Wavelength 578 nm (578-623 nm)
Optical path 1 cm
The reaction involved in the assay system is as follows: Assay type End-point
Urea is hydrolyzed in the presence of water and urease to produce Direction increase
ammonia and carbon dioxide. temperature 15-25 oC or 37 oC
Zero adjustment Against Reagent blank
Urea + H2O Urease 2NH3 + CO2 Reagent Blank Limits Low 0.02 AU
High 0.2 AU
The free ammonia in an alkaline pH and in the presence of indicator Sensitivity 0.6 md/dL (0.1 mmol/l)
forms coloured complex proportional to the urea concentration in Linearity 200 mg/dL (33.3 mmol/l)
the specimen.
Procedure
Reagents
Standard urea (ST) Aqueous primary standard
50 mg/dL 8.33 mmol/l Blank Standard Specimen
Reagent 1 (R1 Buffer) Working solution 1.0 ml 1.0 ml 1.0 ml
Phosphate buffer pH 8.0 100 mmol/l
Sodium salicylate 80 mmol/l
Sodium nitroprusside 6.0 mmol/l Standard ----- 10 µl -----
EDTA 30.0 mmol/l Sample ----- ----- 10 µl
Reagent 2 (R2 Enzyme)
Urease >350000 U/l Mix and incubate for at least 3 minutes at 37 oC or 5 minutes at
20-25 oC .
Reagent 3 (R3 Alkaline Reagent)
Sodium hydroxide 400 mmol/l
Sodium hypochlorite 20.0 mmol/l R3(Alk) 200 µl 200 µl 200 µl
Irritant (xi) R36/38: Irritating to eyes and skin. S26: In case of contact
with eyes, rinse immediately with plenty of water and seek medical Mix and incubate for 5 minutes at 37 oC or 10 minutes at 20-25 oC
advice. S37/39: Wear suitable gloves and eye/face protection. Measure absorbance of specimen (Aspecimen) and standard (Astandard)
against reagent blank .
For further information, refer to the Urea/BUN reagent material safety
data sheet.
Precautions and Warnings
Do not ingest or inhalate. In case of contact with eyes or skin; rinse
immediately with plenty of soap and water. In case of severe injuries;
seek medical advice immediately.
Reagent Preparation , Storage and Stability
To prepare the working solution add the content of one vial of
urease (R2) to one bottle of buffer reagent (R1).
Stability : 2 months at 2-8 oC.
Calculation Anticoagulants
Aspecimen Ammonium heparin should not be used.
Serum urea concentration (mg/dl) = xn
Astandard Others
where n = 50.0 mg/dl (8.33 mmol/l) Ammonium ions should be avoided since it may cause erroneously
elevated results. Color development in the Berthlot reaction is
Urine urea concentration is determined by multiplying the result by suppressed by amines, thiols, steroids and ascorbic acid.
the dilution factor (50).
Expected Values
Urea Nitrogen: To convert the result from urea to urea nitrogen
multiply the result by 0.467. Urea(Serum)
Quality Control Adults <65 years : 15 – 50 mg/dL (2.5-8.33 mmol/L)
Adults >65 years : < 70 mg/dL (<11.66 mmol/L)
Normal & abnormal control serum of known concentrations should
be analyzed with each run. BUN(Serum)
Performance Characteristics Adults <65 years : 7 – 23.5 mg/dL
Precision Adults >65 years : 7 – 32.9 mg/dL
Within run (Repeatiblity) Children : 5 – 18 mg/dL
Level 1 Level 2 Urine (24) hours
n 20 20 Urea : 20 – 35 g/24hrs (330-580 mmol/24hrs)
BUN : 9.3 – 16.4 g/24hrs
Mean (mg/dL) 60 144
SD 1.87 2.1 Spectrum Diagnostics does not interpret the results of a clinical
laboratory procedure; interpretation of the results is considered
CV% 3.12 1.46 the responsibility of qualified medical personnel. All indications
of clinical significance are supported by literature references.
Run to run (Reproducibility)
Analytical Range
Level 1 Level 2
n 20 20 0.6 – 200 mg/dL (0.1 - 33.3 mmol/L).
Mean (mg/dL) 62 146 Waste Disposal
SD 1.92 2.5
This product is made to be used in professional laboratories.
CV% 3.25 1.65 Please consult local regulations for a correct waste disposal.
S56: dispose of this material and its container at hazardous or
special waste collection point.
Methods Comparison S57: use appropriate container to avoid environmental contamination.
S61: avoid release in environment. refer to special instructions/safety
A comparison between Spectrum Diagnostics Urea/BUN reagent data sheets.
and a commercial reagent of the same methodology was performed
on 20 human sera. A correlation of 0.97 was obtained.
References
Sensitivity 1. Batton, C. J & crouch, S.R : Anal. Chem., 1977,49:464-469.
2. Shephard MD, Mezzachi RD : Clin Biochem Revs, 4:61-7, 1983.
When run as recommended, the minimum detection limit of the assay 3. Tietz NW, ED. Clinical guide to Laboratory tests. 2ND ED.
is 0.6 mg/dL. Philadelphia: WB Saunders; 1990:566.
4. Tiffany to, jansen JM, Burtis CA,Overton JB, Scott CD. Enzymatic
Linearity Kinetic Rate and end Point analyses of Substrate, By USE of A
Gemsaec fast analyzer. Clin Chem.
The reaction is linear up to a urea concentration of (200 mg/dl)
33.3 mmol/L. Specimens showing higher concentrations should
be diluted 1+2 with physiological saline and repeat the assay (result•3).
ORDERING INFORMATION
Interfering Substances
Serum, plasma CATALOG NO. QUANTITY
Haemolysis 321 001 1 x 90 ml
Erythrocyte contamination doesn’t elevate results. 321 002 2 x 90 ml
Icterus
No significant interference.
Lipemia
Lipemic specimens interfere with the method of Berthlot.
Egyptian Company for Biotechnology (S.A.E)
Obour city industrial area. block 20008 piece 19 A. Cairo. Egypt.
Tel: +202 4665 1848 - Fax: +202 4665 1847
www.spectrum-diagnostics.com
E-mail:info@spectrum-diagnostics.com
MDSS GmbH
EC REP Schiffgraben 41
30175 Hannover, Germany
IFUFCC47 Rev.(1), 12/9/2007
