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Query: KEGG:D03244 (Kaolin)
 239 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The laboratory assessment of the lupus anticoagulant, a factor frequently associated with venous and arterial thrombosis, recurrent miscarriages and abortions, is not straightforward, as indicated by the variety of tests proposed and the different results obtained. On account of the marked variability and heterogeneity of lupus anticoagulant among patients, no single test or reagent will identify all patients with lupus anticoagulant, and a panel of several tests has to be used. This is time consuming and increases the workload of the laboratory. The aim of this study was to assess the minimum number of tests necessary for the satisfactory identification of the patient with lupus anticoagulant. Our study confirms that lupus anticoagulant may be present in a significant number of patients with normal routine activated partial thromboplastin time, a test which therefore cannot be used as the sole criterion for identifying patients suspected of having lupus anticoagulant. In contrast all patients who had positive results in at least one test could be detected (100% sensitivity) with two combinations of tests: (1) dilute activated partial thromboplastin time and Kaolin clotting time and (2) dilute activated partial thromboplastin time and tissue thromboplastin inhibition test. Since the latter inhibition test has been reported to give a high number of false-positive or negative results, we suggest the combination of dilute activated partial thromboplastin time and Kaolin clotting time as the standard pair of tests for the screening of suspected lupus anticoagulant patients.
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PMID:An evaluation of several laboratory tests and test combinations in the detection of lupus anticoagulant. 150 2

An automated Kaolin Clotting Time (KCT) has been developed to simplify screening for the Lupus Anticoagulant (LA). The assay is performed on the ACL300 Research coagulation analyser, but may be modified for other centrifugal analysers. Automation of the KCT allows up to 17 delta KCT (delta KCT) screens (Gibson J, Starling E, Date L et al. Simplified screening procedure for detecting lupus inhibitor. J Clin Pathol 1988; 44: 226-31) or 2 full Exner curves (Exner T, Rickard KA, Kronenberg H. A sensitive test demonstrating lupus anticoagulant and its behavioural patterns. Br J Haematol 1978; 40: 143-51) to be performed in one test cycle. An automated and manual delta KCT screen was performed on 17 patients with a previously diagnosed LA, 41 hospital patients having routine coagulation studies and 37 blood donors. In addition, 11 patients on full-dose heparin and 12 patients with stable warfarin anticoagulation were tested. The correlation between the automated delta KCT and the manual delta KCT was 0.958 (p less than 0.001). A full Exner curve was performed on 5 of the patients with a LA and 1 blood donor which demonstrated that the automated KCT produced results entirely comparable with the manual method. The automated KCT is a quick, inexpensive approach to screening patients for the presence of LA.
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PMID:Automation of the Kaolin Clotting Time. 157 64

A 37 year-old female was admitted to our hospital because of hypermenorrhea, prolonged bleeding time, thrombocytopenia and the diagnosis of idiopathic thrombocytopenic purpura (ITP) was made. Though activated partial thromboplastin time (APTT) was markedly prolonged, her coagulation factors were within normal ranges. Activities of the circulating lupus anticoagulant (LAC) was suggested. Kaolin clotting time of the platelet poor plasma was used as a sensitive screening test using the mixture of normal and patient's plasma for the detect of LAC. As a result, LAC positive pattern was observed. The treatment with high-dose gammaglobulin brought out a transient increase of the platelet count, but the prolongation of APTT was not corrected. Both the platelet count and the prolongation of APTT were significantly improved after the treatment with betamethasone.
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PMID:[Idiopathic thrombocytopenic purpura complicated with circulating lupus anticoagulant]. 210 46

The prevalence of lupus anticoagulant (LAC) and its relation with reported clinical associations has been determined in 55 patients with systemic lupus erythematosus (SLE) from northern India who were studied prospectively. Kaolin clotting time was used to screen for LAC, which was detected in seven (13%) of the patients. Significant associations were found between LAC and thrombotic events, onset of disease at an early age, and disease of shorter duration. No statistically significant association could be found between LAC and recurrent abortions, pulmonary hypertension, thrombocytopenia, and neurological manifestations. It is concluded that LAC is a useful marker for a subset of patients with SLE at risk of thromboembolic events.
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PMID:Lupus anticoagulants in systemic lupus erythematosus: prevalence and clinical associations. 212 9

Six lyophilized plasma samples were sent to 20 "expert" laboratories for assessment of lupus anticoagulant (LA). Four samples contained pooled LA of graded potency mixed with aged normal plasma. One contained LA plus cephalin phospholipid and one contained a nonspecific venom anticoagulant. Sixteen methods were used overall with some participants using up to 8 methods. Results were scored in regard to the known potencies of LA in the samples and other known induced defects. Activated partial thromboplastin time (APTT) tests used by most participants for preliminary screening were relatively sensitive, but non-specific. Platelet or phospholipid neutralization procedures (PNP) appeared to be sensitive and specific but showed a non-linear response to increased LA content. Kaolin clotting time (KCT) tests showed the most sensitive response to increased LA content but the weaker LA were not scored as abnormal by most laboratories as the samples may have contained platelet fragments. Other commonly used tests such as the tissue thromboplastin inhibition (TTI) test and the dilute Russell's viper venom test (DRVVT) were carried out somewhat inconsistently. The variability in performance of tests in different laboratories indicates that standardization of methodology is urgently required. Generally it seemed that most clotting tests were "bypassed" by the addition of phospholipid to a known LA-positive sample in apparently direct proportion to their sensitivity. Sample preparation, especially prevention of contamination with activated platelets is a vital preliminary part in the assay of LA.
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PMID:Comparison of test methods for the lupus anticoagulant: international survey on lupus anticoagulants-I (ISLA-1). 212 77

Antiphospholipid antibodies (APAs) may be identified in the laboratory by using either coagulation studies or solid-phase immunologic assays (ELISA; RIA). These methodologies do not necessarily evaluate the same antibody; consequently, it is appropriate to screen a patient's plasma by utilizing both assays. APAs have been associated with a variety of obstetrical complications including recurrent spontaneous abortion, intrauterine fetal death, early onset preeclampsia, deep vein thrombosis, and postpartum serositis syndrome. The Kaolin Clotting Time appears to be the most sensitive coagulation test for identifying the lupus anticoagulant. However, preliminary studies would suggest the presence of anticardiolipin antibodies as detected by solid-phase assays are more sensitive and predictive of the clinical course. Although there are no prospective trials to analyze treatment of patients with APA, preliminary data suggest the use of prednisone in combination with aspirin significantly improves the probability of delivery of a viable infant. In addition, heparin, intravenous gammaglobulin, and exchange plasmaphoresis have all been tried with varying degrees of success in individual patients in small series.
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PMID:Antiphospholipid antibodies and reproduction. 251 82

Traditionally, factor XI has been determined in the clinical laboratory by a modified activated partial thromboplastin time assay (aPTT) with factor XI-deficient plasma as the substrate. Coagulant assays, however, have high coefficients of variation. We previously developed a chromogenic assay for factor XI that required equipment not normally found in a clinical laboratory. We now present a modification of that assay, which is performed in 96-well microplates and can be done in any clinical laboratory or physician's office. Plasma is subjected to a brief acidification to inactivate most of the plasma protease inhibitors. Soybean trypsin inhibitor is included to stabilize the factor XIa that is generated. Kaolin is used as the contact activating surface, and the chromogenic substrate, S-2366, is used to measure the factor XIa that is formed. Results of the assay, performed in three groups of subjects, correlate well with results of the coagulant assay as performed in our laboratory and clearly differentiate between total factor XI deficiency and the deficiency of any of the other contact proteins. Unlike coagulation assays, the chromogenic assay is not influenced by the presence of heparin. Furthermore, it is not affected by lupus anticoagulants, which are antibodies directed against acidic phospholipids. Two plasma samples from patients with acquired factor XI inhibitors showed dissociation between coagulant and amidolytic activity, suggesting that the antibodies were not primarily directed toward the active site of factor XIa, which is responsible for its amidolytic activity. In contrast, patients with severe congenital deficiency of factor XI showed no activity by either assay.
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PMID:A simple and accurate microplate assay for the determination of factor XI in plasma. 337 14

The detection of lupus anticoagulant is important in laboratory evaluation of patients with thrombotic tendencies. The aim of this workshop was to assess the effectiveness of Australian laboratories in detecting these antibodies and assess the tests used. Fourteen laboratories took part in the exercise, held as a Workshop of the National Meeting of Australian Medical Laboratory Scientists in 1990. Seven unknown plasmas were distributed for testing prior to the meeting. While 100% correctly identified 3 strong inhibitors and a moderate strength inhibitor, the detection rate for specific individual tests varied from 38-100%. The detection rate for 2 weak inhibitors varied from 0-50%. Of the most commonly performed tests the least sensitive was the dilute Russell's viper venom time and the most sensitive was the tissue thromboplastin inhibition test, however, the degree of sensitivity seemed dependent on the source of thromboplastin. In some laboratories the Kaolin clotting time, with variations, was more sensitive. All participants correctly identified a factor VIII inhibitor as not of the lupus type. The false positive detection rate was 0%. All but one of the participating laboratories used 2 or more phospholipid dependent tests for the analysis of lupus anticoagulant (LA) which is in keeping with current international guidelines.
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PMID:Detection of lupus anticoagulant--an Australian perspective. 816 99

The sera of 69 Chinese patients with systemic lupus erythematosus were tested for the presence of lupus anticoagulant (LA) by a panel of laboratory tests: Kaolin clotting time (KCT), dilute Russell viper venom time (DRVVT) and platelet neutralization procedure (PNP). The prevalence of LA varied among the 3 tests (10-19%), and was 10% when LA was considered present if either KCT or DRVVT and the PNP were positive. Concordance was fair between KCT and PNP, but was poor for DRVVT with either of the other 2 tests. Only 2 of our lupus patients had a history of thrombo-embolic disease, and neither were serologically positive for LA. The incidence of thrombo-embolic diseases and that of LA were both too low in this group of Chinese lupus patients for their association to be evaluated.
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PMID:Evaluation of laboratory tests for lupus anticoagulant in a group of Chinese lupus patients. 816 23

We describe the design of a quantitative test for lupus anticoagulants (LA), based on the Activated Partial Thromboplastin Time (APTT) and the Russell Viper Venom Time (RVVT). In this assay system, test plasmas mixed 1:1 with a pooled normal plasma (NP) are tested at a low as well as a high cephalin concentration, using an ACL 3000 automated clot timer. The ratio of these two clotting times, divided by the corresponding ratio for the NP, was defined as the Lupus Ratio (LR) and calculated by means of a computer program. The frequency distribution of the LR in a reference population of 150 healthy individuals was determined, and the 97.5 percentile was defined as the upper reference limit and allocated the value one Lupus Anticoagulant Unit (LA-U). Using dilutions of one strong LA positive plasma, standard curves for LA-U determination were constructed for the APTT as well as the RVVT based test, and fitted with a log-logit computer model. The sensitivity of the tests was comparable to that of the Kaolin Clotting Time (KCT). Plasma samples from warfarin treated patients were uniformly negative, while most heparin-containing plasmas were positive in both tests. Plasmas deficient in Factors V, VIII and IX were negative, whereas one Factor VIII-inhibitor containing plasma was positive in the APTT and negative in the RVVT. The present work shows that it is possible to adapt the APPT as well as the RVVT for LA quantification. With an automated clot timer and computer based calculation of results, the assays are simple and reproducible and have a high sensitivity and specificity.
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PMID:A quantitative, semi-automated and computer-assisted test for lupus anticoagulant. 844 53


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