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5. BUN and Creat methodologies


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List the 2 main types of BUN methodologies:
1. Indirect methods
2. Direct methods
List the 3 indirect BUN methods?
1. Coupled enzymatic
2. Bertholot
3. Conductimetric
What is the direct BUN method?
Diacetyl monoxime
What is the basic principle of the indirect BUN methods?
-Urea is converted to CO2 NH4 ion;
-The ammonium ion is then measured.
What enzyme is used for "Coupled Enzymatic BUN method"?
What is ultimately measured?
-Urease enzyme
-Final measurement: NAD
What wavelength is NAD measured at?
340 nm
What is ultimately measured in the Berthelot method?
Indophenol Blue product
Why is the Berthelot method less dependible?
Ammonia in the air can cause contamination and nonspecific results.
What is the principle of the Conductimetric method for BUN?
-Ammonium carbonate is formed after urease treatment
-Conductivity increases
What is measured in the Diacetyl monoxime method for BUN?
a yellow diazine product
List 3 different methods for testing Creatinine levels:
1. Jaffe'
2. Jaffe'-Kinetic modification
3. Enzymatic
On what reaction are chemical methods for Creatinine determination based?
Creatinine + picric acid -> orange-red chromagen
What wavelength is the Jaffe method read at?
between 490 and 500 nm
What are interfering substances with the Jaffe method?
Bilirubin, other nonspecific reactants (glucose/ascorbic acid, etc)
What reagent can make the Jaffe reaction more specific?
Lloyd's reagent

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