When a blood ammonia determination is performed, the blood specimen must be treated in a manner that will ensure that

When a blood ammonia determination is performed, the blood specimen must be treated in a manner that will ensure that

• A. The deamination process continues in vitro
• B. Glutamine formation in vitro is avoided
• C. The transamination process continues in vitro
• D. Ammonia formation in vitro is avoided

Answer: (D)

The main idea is that ammonia can be produced in the blood sample after it’s drawn, as cells continue their metabolic processes. If ammonia forms in vitro, the result will be higher than the patient’s true level. To get an accurate measurement, the specimen must be treated to stop these reactions and prevent new ammonia from appearing. In practice, that means cooling the sample immediately and processing it quickly so cellular metabolism is quenched. By preventing ammonia formation in vitro, the measured value more accurately reflects the patient’s in vivo level.

The main idea is that ammonia can be produced in the blood sample after it’s drawn, as cells continue their metabolic processes. If ammonia forms in vitro, the result will be higher than the patient’s true level. To get an accurate measurement, the specimen must be treated to stop these reactions and prevent new ammonia from appearing.

In practice, that means cooling the sample immediately and processing it quickly so cellular metabolism is quenched. By preventing ammonia formation in vitro, the measured value more accurately reflects the patient’s in vivo level.