Why is it important to fill the light blue top tube to the correct volume?

Filling the light blue top tube to the correct volume is crucial because it contains sodium citrate, which is an anticoagulant that requires a specific blood-to-additive ratio to ensure accurate coagulation results. When the tube is not filled to the appropriate volume, the ratio of blood to sodium citrate can be skewed, leading to inadequate anticoagulation or incorrect test results. This can ultimately affect the diagnosis and management of conditions related to blood clotting.

Maintaining the correct volume is essential for tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), where precision in measurements directly impacts clinical decisions. The sodium citrate interacts with the calcium in the blood, and any deviation from the proper volume can alter the function of these tests, making it vital for phlebotomists to ensure that the light blue top tubes are filled accurately.