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Analytical Control
Systems, Inc Analytical Control Systems, Inc. |
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317-841-0458
317-841-3186
Analytical Control Systems, Inc.
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The Lupus Anticoagulant SpeckTin-LA™ Lupus Anticoagulant Titration Set ACS’s SpeckTin-LA™ reagent set can quantitatively detect the lupus anticoagulant. There is a standard amount of phospholipid necessary to satisfy an individual’s clotting reaction. For normal plasma, this is 32 - 50 micrograms per milliliter1, 2. When the lupus anticoagulant is present, it must be neutralized before there will be sufficient phospholipid available for the clotting reaction. SpeckTin-LA™ Lupus Anticoagulant Titration Set provides an accurate measurement of abnormal phospholipid requirements independent of other problems of the coagulation system. The SpeckTin-LA™ Lupus Anticoagulant Titration set contains a series of reagents with different phospholipid levels, 0 µg./ml., 10 µg./ml., 50 µg./ml., 200 µg./ml. and 500 µg./ml. and one vial of Lupus Anticoagulant Control*. Each reagent is run using a standard APTT protocol using the patient’s platelet depleted plasma (platelet poor plasma passed through a 0.22 micron filter). The phospholipid (µg./ml.) is plotted versus the clotting time in seconds and the endpoint, the point at which no further decrease in clotting time is observed by the additional concentrations of phospholipid, is determined. If finer distinctions between the set reagents are needed, the reagents may be mixed in different proportions with the extra 0 µg./ml. reagent to create different concentrations. Endpoints over 50 µg./ml. indicate the presence of the Lupus Anticoagulant. This unique testing program, where the concentration of phospholipid not the clotting time is the determining factor, allows the laboratorian to determine the difference between other abnormalities and the Lupus Anticoagulant. Coumadin therapy, heparin therapy, factor deficiencies, for example, do not effect the endpoint determination. Although the plasma of patients who have other abnormalities in addition to the Lupus Anticoagulant may never return to a normal time to clot formation, the endpoint that determines the phospholipid required to support clotting will still be over 50 µg./ml. if the Lupus Anticoagulant is present and between 32 - 50 if the Lupus Anticoagulant is not present.
Table 4. ACS’s Spectra™ APCT shows good sensitivity to the lupus anticoagulant, factor VIII deficiency, Coumadin therapy and heparin therapy. It is important to note, however, that the SpeckTin-LA™ procedure was only abnormal in the presence of the Lupus Anticoagulant.
Figure 2. The differences in the endpoints between plasma with normal phospholipid requirements and abnormal requirements is illustrated in figure 2. Normal platelet depleted plasma produces a curve with an endpoint between 32-50 µg./ml. and normal clotting times. Figure 3. Plasma from patients who are on heparin therapy, Coumadin therapy or factor VIII deficient plasma do not produce abnormal endpoints although it is possible for the clotting time to remain abnormally long (greater than 40 seconds with an APTT reagent). References:
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