Which tube must be placed on ice and used for lactic acid testing?

Which tube must be placed on ice and used for lactic acid testing?

• A. Gray Tube — Na Fluoride/K Oxalate
• B. Lavender Tube — EDTA
• C. Green Tube — Heparin
• D. Red Tube — No additive

Answer: (A)

For accurate lactic acid measurement, stopping glycolysis and keeping the sample cold immediately after collection is essential. The gray top tube contains sodium fluoride, a glycolysis inhibitor, and potassium oxalate, an anticoagulant. Placing the sample on ice further slows cellular metabolism, helping preserve the lactate level as it was in the body at the moment of collection. This combination is why the gray tube is the best choice: fluoride blocks the enzymatic steps of glycolysis, preventing artificial increases in lactate after draw, while the oxalate keeps the blood from clotting so plasma can be measured. Cooling on ice minimizes metabolic activity during transport and processing. Other tubes lack a glycolysis inhibitor and/or appropriate anticoagulant, so lactate levels would continue to change after collection, leading to inaccurate results.

For accurate lactic acid measurement, stopping glycolysis and keeping the sample cold immediately after collection is essential. The gray top tube contains sodium fluoride, a glycolysis inhibitor, and potassium oxalate, an anticoagulant. Placing the sample on ice further slows cellular metabolism, helping preserve the lactate level as it was in the body at the moment of collection.

This combination is why the gray tube is the best choice: fluoride blocks the enzymatic steps of glycolysis, preventing artificial increases in lactate after draw, while the oxalate keeps the blood from clotting so plasma can be measured. Cooling on ice minimizes metabolic activity during transport and processing.

Other tubes lack a glycolysis inhibitor and/or appropriate anticoagulant, so lactate levels would continue to change after collection, leading to inaccurate results.