REPORTING GUIDE FOR THE ANALYSIS OF UREA ESTIMATION

  • DATE =?
  • TITLE = Urea Estimation by Urease-Berthelot Method
  • AIM = To Analyse a given plasma or serum sample for the estimation of Urea
  • MATERIALS =?

PRINCIPLE:

Urea is hydrolysed in the presence of water and urease to produce ammonia and carbon dioxide. The free ammonia in an alkaline pH and in the presence of indicator forms coloured complex proportional to the urea concentration in the specimen.

  • TABLE OF PROTOCOLS

Reagents and sample

 

Test Tubes

 

 

Blank

 Standard

Sample

R1 Buffer

1.0 ml

1.0 ml

1.0 ml

R2 Enzyme (Urease)

50 ml (1 drop)

 

50 ml (1 drop)

 

50 ml (1 drop)

 

Standard
 

–

10 ml

 

–

Sample

–

–

10 ml

 

 

Mix and incubate for at least 3 minutes at 37 oC or 5 minutes at 20- 25 oC.

R3 (Alk.Reagent)

200 m

200 ml

200 m

 

Mix and incubate for 5 minutes at 37 oC or 10 minutes at 20-25 oC Measure absorbance of specimen and standard against reagent blank.

  • Calculation for the concentration of the urea in the sample

Serum or Plasma urea concentration (mg/dl) = Asample/Astandard  x n

where n = 50.0 mg/dl (8.33 mmol/l)

Urine urea concentration is determined by multiplying the result by the dilution factor (50).

Urea Nitrogen: To convert the result from urea to urea nitrogen multiply the result by 0.467

  • Reference Intervals

< 65 years: 15 – 50 mg/dL (2.5-8.33 mmol/L)

> 65 years: < 70 mg/dL (<11.66 mmol/L)

 

  • COMMENT OR BRIEF DISCUSSION ABOUT RESULT. Differentiation of the cause of abnormal urea concentration = what type of azotaemia is causing the abnormal urea concentration? How to get it is well explained in the learning guide for Clinical Chemistry
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