ASPARTATE AMINOTRANSFERASE DETERMINATION Review Questions and Answers

1.    State the principle of the test.

AST in the serum catalyzes the transfer of an amino acid group to a keto acid group to form oxaloacetate and L-glutamate. This is measured spectrophotometrically at 505-535 nanometers.

2.    Name sources of error in this method.

Hemolyzed serum will increase values 10-15 X
Turbid, lipemic and icteric serum needs serum blanking for accuracy
Altered temperatures could either increase nor decrease values
Prolonged or shortened incubation time at specified conditions could increase or decrease values respectively

3.    What is the purpose of allowing the reagents to come to room temperature.

The purpose is to allow the reagents to inactivate the reagents so that they could react properly.

4.    Differentiate AST from ALT. Cite specific differences.

CRITERIA                     AST                                                      ALT
Substrate    L-aspartate & alpha-ketoglutarate            L-alanine & alpha-ketoglutarate
Old name    SGOT                                                       SGPT
One of the end products    oxaloacetate                       Pyruvate
Amount in inside serum    10-15 times                        5-8 times
Major clinical significance    heart                                Liver
       

5.    What is the component of the SGOT substrate?

L- aspartate and alpha-ketoglutarate