BLOOD COLLECTION TUBES

Cap Color	Additive	Specimen Type	Common Laboratory Tests
Purple / Lavender	EDTA (K2 or K3)	Whole Blood / Plasma	CBC, HbA1c, ESR, Blood Film, Blood Typing
Light Blue	Sodium Citrate (3.2%)	Plasma	Coagulation Studies (PT, APTT, INR, D-Dimer)
Red	None or Clot Activator	Serum	Drug Levels, Serum Chemistry, Serology, Viral Studies
Gold / Tiger	Clot Activator + Gel (SST)	Serum	Chemistry Panels, Thyroid, Lipid Profile, Liver Function
Green	Lithium / Sodium Heparin	Plasma	Electrolytes, STAT Chemistries, Ammonia, ABGs
Gray	Sodium Fluoride + Oxalate	Plasma	Glucose (Fasting/GTT), Lactate, Blood Alcohol
Pink	EDTA (Spray-coated)	Whole Blood	Blood Bank, Cross-matching, Antibody Screen
Royal Blue	None or EDTA / Heparin	Serum or Plasma	Trace Elements (Lead, Zinc, Copper), Toxicology
Yellow	ACD or SPS	Whole Blood	DNA Testing (ACD), Blood Cultures (SPS)

Anticoagulant Tubes (Plasma/Whole Blood): These contain chemicals like EDTA, Heparin, or Citrate that prevent the blood from clotting. After centrifugation, the liquid portion is called plasma, which still contains all clotting factors.
Serum Separator Tubes (SST): These tubes (Gold/Red) contain a clot activator to speed up the natural clotting process. Gold tubes also contain a thixotropic gel that moves between the cells and serum during centrifugation, creating a physical barrier that prevents contamination of the serum.
Glycolytic Inhibitor Tubes: The Gray tube is unique because it contains Sodium Fluoride, which stops red blood cells from consuming the glucose in the sample. This ensures that the glucose reading is accurate even if the sample isn’t tested immediately.

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