Which analytes' values can be affected by delay in processing serum or plasma samples?

• A. Glucose, Calcium, Bicarbonate
• B. Ammonia, Lactic acid, K, Mg, LD, Glucose
• C. Sodium, Chloride, Iron
• D. Creatinine, Uric Acid, Hemoglobin

Answer: (B)

The correct answer highlights analytes that are particularly sensitive to delays in processing serum or plasma samples. In the case of ammonia, lactic acid, potassium, magnesium, lactate dehydrogenase (LD), and glucose, delays can lead to significant alterations in their concentrations due to various biochemical processes that take place post-collection.

Ammonia can increase due to cellular metabolism after the sample is drawn, as cells continue to metabolize and produce ammonia until the sample is processed. Similarly, lactic acid levels can rise due to anaerobic metabolism, especially if the sample is not placed on ice or processed promptly, leading to false elevations that can misrepresent a patient's metabolic state.

Potassium and magnesium are also known to be affected by delays; potassium can leak out of cells, causing pseudohyperkalemia, while magnesium levels can be altered by cellular activity. Glucose concentrations are highly susceptible as well; delays may result in glycolysis, where glucose is consumed by cellular activity, leading to falsely low glucose levels if not processed in a timely manner.

Overall, the analytes listed in the chosen answer are characterized by their vulnerability to changes due to metabolic processes occurring after blood collection, making them critical for timely analysis.