Periodic Table Name

Na

Sodium; found in sodium citrate, sodium fluoride, and sodium heparin.

K

Potassium; found in potassium oxalate.

Li

Lithium; found in lithium heparin.

NH4

Ammonium; found in ammonium heparin. NH4 is an ion, not an element symbol.

Cl

Chloride; commonly measured as an electrolyte.

CO2

Carbon dioxide; measured in chemistry panels and ABG testing.

Fe

Iron; tested with iron studies such as Fe and TIBC.

Ca

Calcium; EDTA and sodium citrate prevent clotting by binding calcium.

Hgb

Hemoglobin; oxygen-carrying protein in red blood cells. Not a periodic-table symbol.

O2

Oxygen; measured in arterial blood gas testing.

Na citrate

Sodium citrate; anticoagulant found in light blue tubes.

Na fluoride

Sodium fluoride; preservative found in gray tubes.

K oxalate

Potassium oxalate; anticoagulant found in gray tubes.

Li heparin

Lithium heparin; anticoagulant found in green tubes.

Na heparin

Sodium heparin; anticoagulant found in green tubes.

NH4 heparin

Ammonium heparin; anticoagulant found in some green tubes.

Light blue tube chemical

Sodium citrate.

Gray tube chemicals

Sodium fluoride and potassium oxalate.

Green tube chemicals

Lithium heparin, sodium heparin, or ammonium heparin.

Tube Chemical Memory

Na citrate = light blue; Na fluoride + K oxalate = gray; Li, Na, or NH4 heparin = green.