Which tube should be used to draw a D-dimer?

The light blue tube is the appropriate choice for drawing a D-dimer. This tube typically contains sodium citrate, which acts as an anticoagulant, ensuring that the blood sample remains in a liquid state by preventing clot formation. For D-dimer testing, which is utilized to help diagnose clotting disorders such as deep vein thrombosis or pulmonary embolism, it is essential that the sample is not coagulated, as this could lead to misleading results.

Using the light blue tube ensures accurate measurement of the D-dimer levels in the plasma. The other tubes listed do not provide the right conditions for this test: the red tube may contain no additives or a clot activator, which could lead to clotting of the sample; the lavender tube generally contains EDTA, which is used for other hematological tests but not suitable for D-dimer testing; and the green tube often contains heparin, which also could interfere with D-dimer results. Therefore, the light blue tube is the standard for D-dimer testing to yield optimal, reliable results.