Which specimens require chilling?

• A. Ammonia
• B. Lactic Acid
• C. ABG
• D. All of the Above

Answer: (D)

Chilling slows metabolic activity and chemical reactions in the sample, helping preserve the exact levels present at collection. Ammonia is highly sensitive to changes after draw; cellular processes can alter NH3/NH4+ balance and even allow some loss to the environment, so placing the specimen on ice keeps the measurement accurate. Lactic acid rises if glycolysis continues in the sample at room temperature, so cooling halts that production and preserves the true lactate level. Arterial blood gas samples are especially time-sensitive because pH and gas tensions can drift as cells continue to metabolize or as gases diffuse; keeping the specimen cold slows these changes and helps maintain the original values until analysis. Because each of these specimen types benefits from reduced metabolic activity after collection, all of them require chilling.