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Kaolin clotting time

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Not to be confused with Kaolin cephalin clotting time. Medical diagnostic method
Kaolin clotting time
Test ofBlood plasma

Kaolin clotting time (KCT) is a sensitive test to detect lupus anticoagulants. There is evidence that suggests it is the most sensitive test for detecting lupus anticoagulants. It can also detect factor VIII inhibitors but is sensitive to unfractionated heparin as well.

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.

History

KCT was first described by Dr. Joel Margolis in 1958. 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. It became the preferred method for lupus anticoagulant testing after Dr. Wilhelm Lubbe showed it to be a good marker for recurrent fetal loss.

Principle

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

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. Therefore, the sample quality is important for the validity of the screening test.

Method

Kaolin

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

Interpretation

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

A good way of expressing the result using mixes is to calculate the Rosner index. 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.

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.

See also

References

  1. Gronowski, Ann M. (2004). Handbook of Clinical Laboratory Testing During Pregnancy. Springer Science & Business Media. p. 308. ISBN 9781592597871.
  2. ^ Radhakrishnan, Kottayam (2013). "Kaolin Clotting Time". Haemostasis. Methods in Molecular Biology. Vol. 992. pp. 335–339. doi:10.1007/978-1-62703-339-8_25. ISBN 978-1-62703-338-1. PMID 23546725.
  3. ^ Exner, T; Triplett, D. A.; Taberner, D. A.; Howard, M. A.; Harris, E. N. (1990). "Comparison of test methods for the lupus anticoagulant: International survey on lupus anticoagulants-I (ISLA-1)". Thrombosis and Haemostasis. 64 (3): 478–84. doi:10.1055/s-0038-1647340. PMID 2128977. S2CID 32243774.
  4. ^ "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. ^ Margolis, J (1958). "The kaolin clotting time; a rapid one-stage method for diagnosis of coagulation defects". Journal of Clinical Pathology. 11 (5): 406–9. doi:10.1136/jcp.11.5.406. PMC 479806. 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. ^ 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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