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Activated Plasma Clotting Time as a Simple Method to Detect Lupus Anticoagulant

By A. Siegemund & H. Scheel Centre of Internal Medicine, University of Leipzig, Germany Feb 1996

In 110 patients with thrombotic events respectively patients with systemic lupus erythematodes anticardiolipin antibodies (ACA) and lupus anticoagulant (LA) were measured. For ACA detecting we used the assays from elias for IgG and IgM- antibodies. We used as sensitive methods for detecting LA in our laboratory the test kits from Dignostica Stago (Staclot LA with hexagonal array of phospholipids, PTT-LA a very sensitive PTT- method and Staclot PNP- a platelet neutralization procedure) and the PTT from Organon Teknika (Platelin Excel LS with two incubation times, 1 and 10 minutes).

The results of these tests were compared with three new ones on the German market: SpeckTin™ APCT (Spectra™ APCT in USA) Activated Plasma Clotting Time, SpeckTin™ APTT (Spectra™ APTT in USA) APTT with purified soy extract and SpeckTin-LA™ (phospholipid preparation in concentrations between 10 and 500 ug/ml); all Wak Chemie.

There were the following results:

1. An increased ratio of SpeckTin APCT/ SpeckTin APTT (>2,7) is evidence for LA
2. In 30 patients with LA we found a sensitivity: 86% for Platelin Excel LS, 91% for PTT-LA, 96% for Staclot LA resp. Staclot PNP, 91% for SpeckTin APCT
3. By titration with SpeckTin-LA we measured the activity of LA; we measured the amount of phospholipid until neutralization of LA and distinguished between high, low or moderate LA.
4. The SpeckTins are simple and specific methods for LA detection and in contrast to Stago methods adaptable on automated coagulation systems.