Anticoagulants
Whole blood or plasma sample investigations need use of anticoagulants while
collecting sample. Some common anticoagulants are:
(a) Ethylenediaminetetraacetic acid: This anticoagulant is used at a concentra-
tion of 2 mg/dl of blood volume. It removes calcium ions by chelation and
block coagulation. It is used mainly for hematological studies.
(b) Heparin: Heparin inhibits conversion of prothrombin to thrombin. Heparin
is present naturally in blood and hence acts as ideal anticoagulant. It
increases the activity of antithrombin. For every ml of blood sample,
0.2 ml of heparin may be used.
(c) Sodiumfluoride: This anticoagulant is considered when glucose estimations
are carried out in blood samples. Sodiumfluoride inhibits glycolysis by
inhibiting activity of enolase enzyme and hence preserves blood glucose
levels. It is generally combined with potassium oxalate because of its poor
anticoagulant action.
(d) Sodium or potassium oxalate: Sodium, potassium, and even lithium
oxalates precipitate calcium ions and inhibit blood coagulation. Potassium
oxalate is more water soluble and is used at concentration of 5–10 mg/5 ml
of blood.2.1 Blood Collection 7