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International Angiology 1998 June;17(2):69-79


lingua: Inglese

Clinical evaluation of new global clotting assay for monitoring of LMWH treatment: Pilot study

Makris P. E., Pithara El.

From the A’ Prop, Med Clinic AHEPA University Hospital, Thessaloniki, Makedonia-Greece


Until now, there has been no reli­able meth­od for the mon­i­tor­ing low molecular weight heparin (LMWH) ther­a­py. Based on our obser­va­tions of the coag­u­lant activ­ity of pseu­do­ser­um ­obtained after clot­ting of recal­ci­fied plas­ma from ­patients who were treat­ed with LMWH, we were led to devel­op a new glo­bal clot­ting assay for the mon­i­tor­ing of this treat­ment.
Methods descrip­tion. After per­form­ing Howell time on PPP, sam­ples were incu­bat­ed for 30 min in 37°C and they were then cen­tri­fuged for 10 min 0.2 ml of this pseu­doserum is added to 0.2 ml of citrat­ed nor­mal plas­ma. Pseudoserum trig­gered coag­u­la­tion of nor­mal plas­ma and the time of new clot for­ma­tion is ­expressed in sec­onds. This assay was ­called ATHU-test (AHEPA Thromb Haem Unit). We test­ed 21 nor­mal sub­jects a in order to ­define the nor­mal mean value and the range of the meth­od. b) We also ­checked the repro­du­cibil­ity of the meth­od by repeat­ing the ATHU-test 17 times on the same nor­mal plas­ma. c) We per­formed in vitro experi­ments to study its reli­abil­ity and we added increas­ing con­cen­trations using given doses of enox­ap­a­rine (4, 8, 12, 16 mg/ml) or frax­ip­a­rine (1.5, 3.0, 4.5, 6 u aXa/ml) which was added in vitro to nor­mal plas­ma con­firm­ing the pro­por­tion­al lin­e­ar regres­sion ­between dura­tion of our test and the ­amount of LMWH. Finally d) we ­checked on the ther­a­py ­response and the LMWH lev­els in blood for throm­bo­phi­liacs.
Results. a) NP, n=21, X=138.6±41.1, range 75-225 sec which means that val­ues >X±3S=261.9 are dis­tinc­tive­ly path­o­log­i­cal. b) The repro­du­cibil­ity of the meth­od is accept­able, CV=9%. c) It is con­firmed that in vitro addi­tion of pre­cau­tion­ary doses of LMWH (1.5 u aXa/ml) ­exceeds the coag­u­la­tion time of ATHU-test up to 300 sec and it fol­lows a dis­tinc­tive­ly pro­por­tion­al rela­tion­ship. d) The mon­i­tor­ing of 20 throm­bo­phi­liacs for 2 ­months ­proved that: i) All their test times were ­between 4-15 min. The more we ­approach the value of 15 min the more dan­ger there is of hae­mor­rhage while, on the con­trary, the more val­ues ­approach 4 min the more the dan­ger of rethrom­bo­sis increases. We ­present the ATHU-test, a sim­ple test which has been used for 6 ­months now by our Unit, in order to con­trol the LMWH ther­a­py for ­patients with throm­boem­bol­ic dis­eas­es. The ATHU-­test’s repro­du­cibil­ity and its small range of nor­mal val­ues, the dis­tinct rela­tion­ship ­between ther­a­peu­tic doses and ther­a­peu­tic clini­cal ­results, as well as the in vitro proof of the lin­e­ar regres­sion ­between the coag­u­la­tion time and the con­tain­ing ­amount of LMWH, are like­ly to esta­blish a new meth­od of ­choice for the mon­i­tor­ing of LMWH ther­a­py.

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