Kaolin clotting time

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Not to be confused with
Kaolin cephalin clotting time
.
Kaolin clotting time
Test ofBlood plasma[1]

Kaolin clotting time (KCT) is a

unfractionated heparin as well.[4]

The KCT on whole blood is known as the "Activated Clotting Time" (ACT) and is widely used in various instruments during surgery such as cardiac bypass to monitor heparin.[5]

History

KCT was first described by Dr. Joel Margolis in 1958.[6] Later on, it was found to be very sensitive to lupus anticoagulants but was only reliable when test plasmas were mixed with normal plasma in various proportions.[3] It became the preferred method for lupus anticoagulant testing after Dr. Wilhelm Lubbe showed it to be a good marker for recurrent fetal loss.[7]

Principle

KCT is similar to the

activated partial thromboplastin time test, except it does not use exogenous phospholipid.[2] Thus, a confirmatory test that uses excess phospholipid is needed to validate the presence of lupus anticoagulants.[2] Otherwise, diluting the test plasma in normal plasma before testing provides characteristic mixing patterns.[8]

Kaolin is the surface activator, and the test also requires small amounts of cell fragments and plasma lipids to provide the phospholipid surface required for coagulation.[2][4] Therefore, the sample quality is important for the validity of the screening test.[2]

Method

Kaolin

The test combines a test

kaolin, and after a brief pre-incubation and the addition of calcium chloride, the time to clot (in seconds) is measured.[6] Mixes of patient plasma with normal plasma are recommended for testing.[9]

Interpretation

The KCT test/control ratio of greater than or equal to 1.2 indicates that a defect is present.[4] If the test/control ratio is between 1.1 and 1.2, the test is equivocal.[4]

A good way of expressing the result using mixes is to calculate the Rosner index.[10] If A is the KCT of normal plasma, B is that of the 1:1 mix and C is that of the patient plasma, then the Rosner index is 100x(B-A)/C. Values above 15 indicate a positive result but in most cases labs set their own cutoff values.[9]

If the KCT is less than 60 seconds, this suggests that the test plasma is contaminated with platelet fragments; therefore, the test is not valid.[4]

See also

References

  1. ISBN 9781592597871
    .
  2. ^
    PMID 23546725
    .
  3. ^
    S2CID 32243774
    .
  4. ^ a b c d e "Kaolin Clotting Time [KCT]". Archived from the original on 26 November 2014. Retrieved 26 November 2014.
  5. ^ De Vries, A.J.; Lansink-Hartgring, A,O.; Fernhout, F.J.; Huet,R,C,G.; van den Heuvel, E,R. (2017) "The activated clotting time in cardiac surgery: should celite or kaolin be used?" Interact Cardiovascular and Thoracic Surgery. 24 (4): 549-554
  6. ^
    PMID 13575555
    .
  7. ^ Lubbe, W.F.; Butler, W.S.; Palmer, S.J.; Liggins, G.C. (1983). "Fetal survival after prednisone suppression of maternal lupus-anticoagulant". Lancet. June 18;(8338):1361-3
  8. ^ Exner,T (1978). "A sensitive test demonstrating lupus anticoagulant and its behavioural patterns". British Journal of Haematology. 40 (1): 143-51.
  9. ^ a b Ledford-Kraemer, L. et al (2014). "Laboratory testing for the lupus anticoagulant". CLSI; H60 1st edition.
  10. ^ Rosner, R.; Pauzner, R.; Lusky, A. (1987). "Detection and quantitative evaluation of lupus anticoagulant activity". Thrombosis and Haemostasis.57;144-7.
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