Additives

EDTA

Lavender or pink tube; binds calcium to prevent clotting.

Sodium citrate

Light blue tube; binds calcium and preserves clotting factors for coagulation tests.

Heparin

Green tube; prevents clotting by stopping thrombin activity; used for chemistry and STAT tests.

Sodium fluoride

Gray tube; prevents glycolysis and preserves glucose.

Potassium oxalate

Gray tube; binds calcium and prevents clotting.

Clot activator

Red or SST tube; helps blood clot faster.

Gel

SST or PST tube; separates serum or plasma from blood cells after centrifugation.

SPS

Yellow blood culture tube; helps preserve microorganisms for blood cultures.

Calcium-binding additives

EDTA, sodium citrate, and potassium oxalate bind calcium to prevent clotting.

Fluoride memory

Sodium fluoride saves glucose by stopping glycolysis.

Heparin memory

Heparin prevents clotting by stopping thrombin activity.