What is Anticoagulants? Explanation and Preparation

Whole blood is nec­es­sary for most hemolyt­ic inves­ti­ga­tions the sam­ple must there­fore be mixed with an anti­co­ag­u­lant to pre­vent coag­u­la­tion. Anti­co­ag­u­lants are defined ad sub­stances which pre­vent blood clotting/coagulation allow sep­a­ra­tion of the blood into cel­lu­lar and liq­uid (plas­ma) com­po­nents. Gen­er­al­ly plas­ma con­tains coag­u­la­tion factors. 

• Save

The com­mon hema­to­log­i­cal anti­co­ag­u­lant is list­ed below:

Double oxalate

0.5 anti­co­ag­u­lant for 5ml of blood 

Chem­i­cal Action : This anti­co­ag­u­lant removes the free cal­ci­um ion from solu­tion through the addi­tion of ammo­ni­um and potas­si­um oxalate. Cal­ci­um is pre­cip­i­tat­ed as insol­u­ble cal­ci­um oxalate.

Prepa­ra­tion:

1. 1–2 gram ammo­ni­um oxalate and 0.8 gm potas­si­um oxalate are dis­solved in 100ml of dis­tilled water.
2. 0.5 ml of this solu­tion is added to each of a series of tubes and evap­o­rat­ed to dry­ness at 37°C high­er tem­per­a­ture decom­pose the exalted.

Use :- Blood tak­en into this anti­co­ag­u­lant is unsuit­able for mor­pho­log­i­cal exam­i­na­tion, the red cells com­merce to cre­nate and the white exhib­it bizarre nuclear patterns.

Ethylene Diamine Tetra Acetic Acid (EDTA)

Eth­yl­ene Di amine Tetra acetic acid (Edta ) can be found in three salt forms:

• Tri potas­si­um EDTA
• Di sodi­um EDTA
• Di Lithi­um EDTA

Also, Edta can be crys­talline or liq­uid . liq­uid EDTA tubes require spe­cif­ic fil­ing vol­ume to avoid dilu­tion effect. So, blood : Anti­co­ag­u­lant ratio must be main­tained (This is applic­a­ble to all anti­co­ag­u­lants ). EDTA is also known as versene or sequences. EDTA acts by chelat­ing ion­ized cal­ci­um . Gen­er­al­ly tri potas­si­um EDTA is bet­ter than di sodi­um EDTA and di — Lithi­um EDTA.

Always be sure to mix blood with anti­co­ag­u­lant in an man­ner that guar­an­tee prop­er com­plete mix­ing. By gen­tle repeat­ed inver­sion since this may cause hemol­y­sis and dis­in­te­gra­tion of cells and the final effect will be erro­neous low result for cel­lu­lar com­po­nents of blood EDTA is the most com­mon­ly used anti­co­ag­u­lant in the hema­tol­ogy lab­o­ra­to­ry and is the anti­co­ag­u­lant of choice for the CBC.

Heparin

Heparin is an acid Mucopolysac­cha­ride it acts by com­plex­ing with antithrom­bin to pre­vent blood clot­ting (antithrom­bin is one of the natural/physiological inhibitors of blood coag­u­la­tion). It is not suit­able for blood films stain­ing since it gives too blue col­oration to the back­ground when films are stained with row­man­wosky stains also heparin May cause leuko­cyte and platelets, clump­ing this is why heparin is not suit­able for rou­tine hematology.

Sodium Citrate

Sodi­um cit­rate has been used as an anti­co­ag­u­lant to sta­bi­lize blood and blood prod­ucts for over 100 years, pre­sum­ably by seques­ter­ing Ca(++) ions in vit­ro. Anti­co­ag­u­la­tion of blood with­out chela­tion can be achieved by inhi­bi­tion of the con­tact path­way by corn trypsin inhibitor (CTI).

Sodium Fluoride

This anti­co­ag­u­lant is used for prepar­ing blood spec­i­mens for the deter­mi­na­tion of glu­cose and urea in plas­ma by non enzy­mat­ic meth­ods. Flu­o­ride inhibits gly­colyt­ic enzymes and there­by pre­vents loss of glu­cose dur­ing trans­porta­tion or delay in spec­i­men han­dling as flu­o­ride is not a strong anti­co­ag­u­lant it is mixed with oxalate.