MAKING ADSORBED PLASMA
Dr. Mehmood-ul-Hasan
Adsorbed plasma is used for mixing studies in coagulation disorders testing laboratory.
PRINCIPLE:
Barium sulphate adsorbs (cf. absorb) clotting factors II, VII, IX, and X. When Prothrombin time (PT) or Activated Partial thromboplastin time (APTT) is performed on test plasma deficient of any of factor II, VII, IX, X , these tests show prolonged results. When these tests are repeated after mixing Adsorbed plasma with this test plasma, PT and APTT are still prolonged i.e. not corrected, because adsorbed plasma has not any ability to correct the deficiency. If the test plasma is deficient in factors other than factor II, VII, IX, and X, on mixing with adsorbed plasma, it will replenish those factors from adsorbed plasma, thus the tests will be said to be corrected.
REQUIREMENTS:
Barium sulphate
Weighing machine
Test tubes
Glass rod
Cuvets
Micropipette
Filter paper
Water bath
Prothrombin reagent
Normal Blood samples in trisodium citrate tubes
Centrifuge
Refrigerator
PROCEDURE:
1. Blood samples are taken from 10 healthy donors in trisodium citrate tubes.
2. Platelet poor plasma is made by centrifuging each sample @4000 rpm/min for 15 min.
3. Prothrombin time is noted. Normal samples are separated.
4. Samples with normal values are poured in a test tube, thus making a pool. Volume is noted in mL.
5. Barium sulphate is weighed @100mg/mL pool plasma.
6. Barium sulphate is mixed frequently in the pool plasma by a glass rod in a water bath at 37C.
7. After 15 min, a slow spin @1000 rpm/min is given to the pool plasma for 3 min. Barium sulphate settles down.
8. Prothrombin time is performed on the supernatant.
9. If it is 60 - 80 sec, the process is complete. Store the adsorbed plasma at -30C in labelled cuvets.
10. If it is < 60sec, add more Barium sulphate e.g. 10 mg, and start from step 6.
11. If it is more than 80 sec, add more pool plasma (already separated aliquots), and start from step 6.
12. Ensure writing Prothrombin time and date of manifacturing on the cuvet or the container having cuvets.
PRECAUTIONS:
1. Barium sulphate should not be expired for date.
2. Glassware must be clean.
3. Temperature of the water bath should be at 37 C.