Impact of different preanalytical conditions on results of lupus anticoagulant tests

Abstract

Introduction:The currently recommended preanalytical conditions for lupus anticoagulant (LA) analysis require analyzing samples in fresh or freshly frozen platelet-poor plasma. The aim of this study was to evaluate whether alternative and less cumbersome preanalytical procedures for LA testing give significantly different results compared to recommended conditions. Materials and Methods: Citrated blood samples were drawn from 29 study participants, 15 with negative and 14 with positive LA results. The samples were processed according to the ISTH guideline for LA testing and compared to several alternative preanalytical conditions. Measurements were performed using the dilute Russell's viper venom time (DRVVT) and silica clotting time (SCT), both screen and confirm, on a STA-R Evolution analyzer. Stability criteria were based upon biological variation.Results: All DRVVT tests (normalized screen, confirm, and screen/confirm ratio) met the stability criteria for all the preanalytical conditions. The SCT tests (normalized screen, confirm, and screen/confirm ratio) met the stability criteria only when treated according to the ISTH guideline, except for SCT normalized screen/confirm ratio which also met the stability criteria for double-centrifuged aliquoted plasma stored in room temperature for 24 hours and then analyzed "fresh" or after being frozen. One warfarin-treated patient was reclassified from positive to negative for DRVVT after the preanalytical modifications, while 2 of 29 participants became falsely positive for 2 of 8 conditions for SCT. Conclusions:The DRVVT assays met the criteria for stability for all preanalytical conditions tested, while the SCT assays should be interpreted with caution if the preanalytical guidelines from ISTH are not followed. K E Y W O R D S dilute Russell's viper venom time, lupus anticoagulant, preanalytical conditions, silica clotting time, stability

Platelet Counts Analysis of Platelet-Poor Plasma (PPP) Produced by Several Centrifugation Techniques

“…The lowest platelet count (<3×10 3 /µL) was obtained from the 1,500 g centrifugation technique for 15 minutes twice. This result was similar to a previous study conducted by Kristoffersen and Sicard which showed that the number of platelets of PPP produced by doing 1,500 g of centrifugation for 15 minutes twice and 3,260 g of centrifugation in 10 minutes was <10,000/ µL [6,11] . This study was the first study to examine the centrifugation of 3,000 g for 15 minutes.…”

“…The preparation of PPP recommended by the Clinical and Laboratory Standart Institute (CLSI) is to use a tube with sodium citrate anticoagulant and centrifugation processes at a speed of 1,500 g for at least 15 minutes [5] . Different results were obtained in a study conducted by Kristoffersen which stated that the number of platelets after a single 1,500 g centrifugation results in a platelet count <22,000/µL [6] . Magnette et al recommend a repeat of centrifugation to ensure platelet residue is less than 10,000/µL.…”

“…The remaining platelet in plasma has been known to affect phospholipid-dependent coagulation tests such as those on Lupus Anticoagulant (LA) [7] . This repeating centrifugation process must be prepared for all coagulation parameters if there is a possibility that the measurement is not carried out immediately after centrifugation, or if the sample will be frozen [6][7][8][9][10] .…”

Testing for Lupus Anticoagulants

“…21 It is common to freeze plasmas for batched analysis at a later date which exacerbates this problem because the freeze/thaw process ruptures platelet membranes, resulting in excess PL in the plasma samples and risking further LA quenching. 22 Ultracentrifugation might seem a straightforward alternative but is discouraged as it can generate platelet microparticles capable of quenching LA. 6,7,23 Filtering plasma through 0.22-µm cellulose acetate filters will remove all platelets but is also discouraged because of microparticle generation, and additionally, it can induce loss of von Willebrand factor (VWF) and some coagulation factors.…”

The Effect of Storage and Time of Blood Specimen Examination of Plasma Prothrombin Time and Activated Partial Thromboplastin Time Stabilities

“…In most cases, laboratories can safely use manufacturer's or published study information to determine the stability of the specimen, but in some conditions the stability of the specimen is not available yet [3,4,5,6] . Because of this reason, research related to recommendations of storage and examination time on the stability of PPT and aPTT blood specimens in the testing of coagulation physiology in Dr. Soetomo Hospital laboratory is very important, considering that the results of an accurate, fast, and precise testing is closely related to the financing and quality of blood testing services at Dr. Soetomo Hospital, Surabaya, Indonesia.…”