The claim that EDTA in a green-top tube can cause a falsely low reading for electrolyte testing is true.

The claim that EDTA in a green-top tube can cause a falsely low reading for electrolyte testing is true.

• A. True
• B. False
• C. Not sure
• D. It depends

Answer: (B)

The main idea is that the anticoagulant in the tube used for electrolyte testing determines whether EDTA-related interference can occur. Green-top tubes contain heparin, not EDTA, so there is no EDTA in that tube to chelate calcium or otherwise skew results. EDTA’s chelating action would mainly affect calcium- and magnesium-related measurements, and can cause falsely low values if EDTA were present. Since the green-top tube does not contain EDTA, the claim that EDTA in a green-top tube causes a falsely low electrolyte reading is not true. For electrolyte testing, green-top tubes are appropriate because heparin preserves plasma without chelating calcium. If EDTA contamination did occur (using the wrong tube), it could alter some electrolyte results, particularly calcium and magnesium, but that scenario is due to contamination, not a property of the green-top tube itself.

The main idea is that the anticoagulant in the tube used for electrolyte testing determines whether EDTA-related interference can occur. Green-top tubes contain heparin, not EDTA, so there is no EDTA in that tube to chelate calcium or otherwise skew results. EDTA’s chelating action would mainly affect calcium- and magnesium-related measurements, and can cause falsely low values if EDTA were present. Since the green-top tube does not contain EDTA, the claim that EDTA in a green-top tube causes a falsely low electrolyte reading is not true. For electrolyte testing, green-top tubes are appropriate because heparin preserves plasma without chelating calcium. If EDTA contamination did occur (using the wrong tube), it could alter some electrolyte results, particularly calcium and magnesium, but that scenario is due to contamination, not a property of the green-top tube itself.