Which specimen needs to be chilled?

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Multiple Choice

Which specimen needs to be chilled?

Ammonia must be chilled because it is highly labile in a blood specimen. After blood is drawn, cellular enzymes continue to metabolize compounds that can alter ammonia levels, so keeping the sample on ice slows this metabolism and preserves the in vivo concentration. If the sample warms or sits at room temperature, ammonia can increase, leading to falsely elevated results. Bilirubin is primarily protected from light because it is photolabile, so keeping it out of direct light is the key handling step rather than chilling. Cold agglutinin testing requires maintaining warmth to prevent red blood cells from clumping; cooling would promote agglutination and skew results. Serum protein can be stable under typical handling conditions and does not require immediate chilling for the test in question, so chilling isn’t specifically needed to preserve it.

Ammonia must be chilled because it is highly labile in a blood specimen. After blood is drawn, cellular enzymes continue to metabolize compounds that can alter ammonia levels, so keeping the sample on ice slows this metabolism and preserves the in vivo concentration. If the sample warms or sits at room temperature, ammonia can increase, leading to falsely elevated results.

Bilirubin is primarily protected from light because it is photolabile, so keeping it out of direct light is the key handling step rather than chilling. Cold agglutinin testing requires maintaining warmth to prevent red blood cells from clumping; cooling would promote agglutination and skew results. Serum protein can be stable under typical handling conditions and does not require immediate chilling for the test in question, so chilling isn’t specifically needed to preserve it.

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