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Urea (Ned Method) : CODE NO. PACK SIZE Reagent 1 Reagent 2 Reagent 3

This document provides instructions for quantitatively determining urea levels in serum or plasma using a fixed-time colorimetric assay. Urea reacts with ortho-phthalaldehyde and naphthylethylene diamine to form an orange complex, the rate of which is directly proportional to the urea concentration. The procedure involves adding patient sample and reagents to test tubes and measuring absorbance changes at 505nm over 60 seconds. By comparing absorbance changes to a urea standard, the urea level in the patient sample can be calculated and reported in mg/dL. Elevated levels may indicate renal or liver diseases while decreased levels can be seen in liver failure or pregnancy.

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Dharmesh Patel
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4K views1 page

Urea (Ned Method) : CODE NO. PACK SIZE Reagent 1 Reagent 2 Reagent 3

This document provides instructions for quantitatively determining urea levels in serum or plasma using a fixed-time colorimetric assay. Urea reacts with ortho-phthalaldehyde and naphthylethylene diamine to form an orange complex, the rate of which is directly proportional to the urea concentration. The procedure involves adding patient sample and reagents to test tubes and measuring absorbance changes at 505nm over 60 seconds. By comparing absorbance changes to a urea standard, the urea level in the patient sample can be calculated and reported in mg/dL. Elevated levels may indicate renal or liver diseases while decreased levels can be seen in liver failure or pregnancy.

Uploaded by

Dharmesh Patel
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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UREA (NED METHOD)

INTENDED USE:
The reagent kit is intended for "in vitro" Quantitative
determination of Urea in Serum and plasma.

CLINICAL SIGNIFICANCE: PROCEDURE:


Urea is the end product of the protein metabolism. It is Pipette into clean dry test tubes labeled as Standard (S) and Test (T) :
synthesized in the liver from the ammonia produced by the
catabolism of amino acids. It is transported by the blood to the Addition sequence S T
kidneys from where it is excreted. Increased levels are found in OPA Reagent 1 ml 1ml
renal diseases, urinary obstructions, shock, congestive heart Sample - 50µl
failure and burns. Decreased levels are found in liver failure and Standard 50 µl -
pregnancy. Mix Well
NED Reagent 0.5 ml 0.5 ml
PRINCIPLE:
Mix well and read the initial absorbance A1 for the standard and
Urea reacts with ortho - pthalaldehyde and Napthylethylene
Test after exactly 60 seconds . Read another absorbance A2 of
diamine to form an orange cololured complex. The rate of
the standard and Test exactly 60 seconds later at 505 nm.
formation of this complex is directly proportional to urea conc.
and it is measured by a fixed time mode at 505 nm. Calculate the change in absorbance DA for both the standard
and Test.
REACTION: For, Standard DAS = AS
2 - AS
1
+
Urea + OPA NH 4 + HO
2 Test DAT= AT
2 - AT1

NH4
+
+ NED Orange Color Complex
CALCULATION :
DAT
Urea Concentration (mg/dl) = x 50
CONTENTS: DAS
Reagent 1 : OPA Reagent NORMAL VALUE :
Reagent 2 : NED Reagent
Reagent 3 : Urea Standard, 50 mg/dl Serum/plasma : 15-50 mg/dl
Each laboratory should establish it's own normal range
MATERIALS REQUIRED BUT NOT PROVIDED:- representing its patient population.
- Clean & Dry Glassware.
- Laboratory Glass Pipettes or Micropipettes & Tips. LINEARITY :
- Colorimeter or Bio-Chemistry Analyzer.
The procedure is linear upto 200 mg/dl. If the value exceed this
SAMPLES: limit, dilute the serum with normal saline (NaCl 0.9 %) and
Serum, Heparinized/EDTA Plasma. Urea is reported to be stable repeat the assay. Multiply result by dilution factor.
0
in the serum for 5 days when store at 2-8C.
QUALITY CONTROL :
PREPARATION OF REAGENT & STABILITY : For accuracy it is necessary to run known controls with every
All reagents are in ready to use form. assay.
All reagents are stable till the expiry date mentioned on the
bottle at Room temperature. LIMITATION & PRECAUTIONS :
The Standard reagent is stable till the expiry date mention on the 1.Storage condition as mentioned on the kit should be strictly
vial at 2 - 8° C. adhered.
2. Do not freeze the reagents.
GENERAL SYSTEM PARAMETERS: 3.Before assay run bring all reagents to room temperature.
4.Use glassware free from ammonium ions, dust or debris.
Reaction type : Fixed Time (Increasing)
Wave Iength : 505 nm (490 - 520 nm)
BIBLIOGRAPHY :
Temperature : 37°C
1. Gordon, T., and M., Amer.J.Med.; 62 (1977) 707
Delay time : 60 Sec
2. Friedewald, W.T. etal., clin.chem.; 18 (1972) 499
Read time : 60 Sec.
OPA Reagent : 1.0 ml CODE NO. PACK SIZE Reagent 1 Reagent 2 Reagent 3
NED Reagent : 0.5 ml Z18 100 ml 1 x 100 ml 1 x 50 ml 3.0 ml
Sample volume : 50 µl.
Standard concentration : 50.0 mg/dl
Zero setting : Deionised water
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Light path : 1 cm IVD ISO 9001:2015 ISO 13485:2003

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