Medicine:Kaolin clotting time
| Kaolin clotting time | |
|---|---|
| Medical diagnostics | |
| Test of | Blood plasma[1] |
Kaolin clotting time (KCT) is a sensitive test to detect lupus anticoagulants.[2] There is evidence that suggests it is the most sensitive test for detecting lupus anticoagulants.[3] It can also detect factor VIII inhibitors but is sensitive to 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
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.[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
- Dilute Russell's viper venom time
- Partial thromboplastin time
- Activated clotting time
References
- ↑ Gronowski, Ann M. (2004) (in en). Handbook of Clinical Laboratory Testing During Pregnancy. Springer Science & Business Media. p. 308. ISBN 9781592597871. https://books.google.com/books?id=Dt_OBgAAQBAJ&pg=PA308.
- ↑ 2.0 2.1 2.2 2.3 2.4 Radhakrishnan, Kottayam (2013). "Kaolin Clotting Time". Haemostasis. Methods in Molecular Biology. 992. pp. 335–339. doi:10.1007/978-1-62703-339-8_25. ISBN 978-1-62703-338-1.
- ↑ 3.0 3.1 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.
- ↑ 4.0 4.1 4.2 4.3 4.4 "Kaolin Clotting Time [KCT"]. http://www.practical-haemostasis.com/Thrombophilia%20Tests/APS/kct.html/. Retrieved 26 November 2014.
- ↑ 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
- ↑ 6.0 6.1 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. PMID 13575555.
- ↑ 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
- ↑ Exner,T (1978). "A sensitive test demonstrating lupus anticoagulant and its behavioural patterns". British Journal of Haematology. 40 (1): 143-51.
- ↑ 9.0 9.1 Ledford-Kraemer, L. et al (2014). "Laboratory testing for the lupus anticoagulant". CLSI; H60 1st edition.
- ↑ 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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