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Kaolin Clotting Time (KCT)
Message"Do not draw from an arm with a heparin lock or heparinized catheter
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Test Code
500128
CPT Codes
85347
Preferred Specimen
"Plasma (platelet poor), frozen
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Minimum Volume
"1 mL
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Instructions
"Freeze. Stable at room temperature for up to four hours.
Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge and carefully remove the plasma using a plastic transfer pipette, being careful not to disturb the cells. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
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Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge and carefully remove the plasma using a plastic transfer pipette, being careful not to disturb the cells. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
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Transport Container
"Blue-top (sodium citrate) tube
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Methodology
"In the kaolin clotting time (KCT) test, kaolin, a negatively-charged particulate activator, is incubated with test plasma to activate the contact factors and the intrinsic system.11 Calcium chloride is added and the mixture is timed until a clot forms. "
Limitations
"Due to the heterogeneity of LA antibodies, no single assay will identify all cases.7 The KCT is prolonged in patients with factor deficiencies of all factors except factor VII or XIII deficiency.11 Platelet-poor plasma must be used for this test as the presence of platelets causes all the clot-based tests to loose sensitivity for the presence of lupus anticoagulants. The KCT test can be affected by the presence of therapeutic plasma heparin. Specific inhibitors to coagulation factors can cause prolongation of this test.
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Reference Range
"50-130 units
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