Which anticoagulant is found in a light blue-topped blood collection tube?

The correct answer is sodium citrate, which is the anticoagulant present in light blue-topped blood collection tubes. Sodium citrate functions by binding calcium ions in the blood, which are crucial for the coagulation process. This anticoagulant is primarily used for coagulation studies, such as PT (prothrombin time) and aPTT (activated partial thromboplastin time), due to its ability to preserve the functional properties of the clotting factors during testing.

In contrast, other anticoagulants serve different purposes: EDTA is used in lavender-topped tubes and works by chelating calcium for hematology tests, sodium heparin is found in green-topped tubes and is used primarily for plasma chemistry tests, and calcium oxalate, typically in gray-topped tubes, is used for glucose testing. Understanding the specific function and application of each anticoagulant is crucial for proper blood collection and subsequent analysis in laboratory settings.