Laboratory

GOT-AST: programming in a semi-auto biochemistry analyzer

GOT-AST

Glutamate Oxaloacetate Transaminase (aspartate aminotransferase) is an enzyme that is mostly present in the liver cells, kidney, skeletal system, and heart muscles. An increase in the value of GOT-AST in the blood mainly indicates that there is damage to those major organs. Similarly, a lower level of GOT-AST can be due to pregnancy, diabetic ketoacidosis, etc.

Everything that I state below will be based on a semi-auto biochemistry analyzer and can differ from one manufacturer to another.

Principle reaction

AST enzyme converts the 2-oxoglutarate, and L-aspartate to L-glutamate and oxaloacetate. The oxaloacetate reacts with NADH in the presence of malate dehydrogenase (MDH) to form NAD. The rate of degradation of NADH to NAD causes a decrease in the absorbance of the light. This is proportional to the activity of the GOT-AST enzyme.

Stability

Normally, you can store both the reagents (R1 and R2) at 2-80C  till the expiration date. But, once you open the bottle, the lifespan will reduce to about 28 days (at 2-80C ) for R1 and 90 days for R2. Also,  for a working solution, the lifespan will be about  14 days.

Handling

  • Wear an apron and surgical gloves before carrying out the measurement.
  • Look for the expiry date of the reagents during purchase and measurement time. Suppliers tend to give you reagent kits with a low expiry interval.
  • Bring the reagents and samples to room temperature before you can carry out any measurement.
  • Always store reagents in the refrigerator when not in use.

Sample preparation

To prepare the working solution, mix R1 and R2 reagents in a ratio of 5:1. After that, add 100 μl of sample to 1000 μl of the prepared working solution. Finally, feed the solution into a semi-auto biochemistry analyzer and get the result.

If the activity of the GOT-AST enzyme is very high (out of range), you need to dilute it with 0.9% NaCl or distilled water in a ratio of 1: y. Then when you get the final result, multiply the value with a dilution factor (1+y).

You will get a decreasing curve in the biochemistry analyzer.

Programming for GOT-AST in a semi-auto biochemistry analyzer (IFCC method)

GOT-AST, semi-auto biochemistry analyzer

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