Current CLSI standards require a phlebotomist to draw which tube before a light blue topped tube?

The correct choice is to draw a red top tube before a light blue top tube due to the order of draw established by the Clinical and Laboratory Standards Institute (CLSI). This order is important to prevent cross-contamination of additives from one tube to another, which can skew test results.

Red top tubes contain no additives, making them suitable for serum tests where the separation of serum from cells is necessary. Drawing a red top tube first ensures that any potential contaminants from the serum tube do not interfere with the coagulation tests performed on the light blue top tube, which contains sodium citrate as an anticoagulant. Sodium citrate is sensitive to certain types of contamination, and any chemically reactive substances or additives from other tubes can affect coagulation results.

Alternatively, the specified tubes in the other options, such as the green top tube, yellow top tube, and tiger top tube, each contain specific additives that can alter test results if drawn before the light blue tube. Therefore, following the established order of draw is crucial for obtaining accurate laboratory results.