What is the purpose of potassium oxalate in blood collection tubes?

Potassium oxalate serves as an anticoagulant in blood collection tubes. Its primary function is to prevent blood from clotting by chelating calcium ions in the sample. Calcium is essential for the coagulation process, and by binding to it, potassium oxalate effectively inhibits the formation of clots, thus allowing for a liquid sample to be obtained for further testing.

This property is particularly important in situations where accurate results for various tests, such as blood glucose or certain metabolic panels, are needed. The ability to keep the blood in a liquid state ensures that the components remain evenly distributed, facilitating a more accurate assessment of analytes within the sample.

While the other options might seem plausible in different contexts—like preserving glucose levels, which typically requires a different preservative such as sodium fluoride, or preventing hemolysis, which can be influenced by factors such as collection technique and handling—the primary role of potassium oxalate is specifically as an anticoagulant in blood collection tubes.