Which of the following statements describes a handling step that is not required for ammonia analysis?

• A. Place specimen in a 37°C water bath immediately.
• B. Avoid using a hemolyzed specimen.
• C. Collect blood in EDTA or heparin evacuated tubes.
• D. Advise patient not to smoke for 8 hours before blood collection.

Answer: (A)

Ammonia analysis is highly sensitive to preanalytic handling, especially temperature and cellular activity after collection. To obtain a true in vivo level, the specimen must be kept cold (on ice) and processed promptly to halt ongoing metabolism that could produce additional ammonia. Placing the sample in a 37°C water bath is not required and would promote metabolic activity after collection, potentially elevating the measured ammonia and yielding an inaccurate result. In practice, avoiding hemolyzed samples is crucial because red cell rupture releases intracellular ammonia, inflating results. Collecting blood in anticoagulant tubes such as EDTA or heparin prevents clotting and preserves plasma for accurate measurement. Advising the patient not to smoke for several hours before collection helps minimize transient factors that can alter ammonia levels.