Prothrombin activation in eastern tiger snake bite.
OBJECTIVE
To perform ex vivo studies in eastern tiger snake envenomation which define the haemostatic events associated with prothrombin activation.


METHODS
Serial studies were performed on plasma from six individuals with evidence of eastern tiger snake envenomation. These analyses were particularly directed to fibrinogen levels, F1 + 2, TAT and evidence of fibrinolysis.


RESULTS
There was a substantial rise in F1 + 2 and thrombin-antithrombin (TAT) complexes in all cases, even with minimal evenomation. In some cases the molar ratio of F1 + 2 and TAT was reduced from the relationship normally seen in vitro and ex vivo in clinical thrombosis. There was a dramatic fall in factor V and VIII levels which occurred 4-6 hours before the decline in prothrombin and AT3. This related in time to a fall in alpha2AP and plasminogen. Protein C levels also declined dramatically but many hours after presentation.


CONCLUSIONS
F1 + 2 and TAT are sensitive markers of tiger snake evenomation. In some patients with massive prothrombin activation, the common mechanism for TAT clearance may be altered or overwhelmed. Conversely, the renal clearance of the smaller F1 + 2 may be enhanced. In the absence of thrombocytopaenia, which is a very sensitive marker of DIC, the fall in labile factors with tiger snake envenomation is significantly contributed to by proteolytic digestion of clotting factors.
Parkin
John Desmond
JD
Division of Laboratory Medicine, Austin and Repatriation Medical Centre, Melbourne, Victoria, Australia. des.parkin@armc.org.au
Ibrahim
Kamal
K
Dauer
Raymond John
RJ
Braitberg
George
G
D000293:Adolescent; D000328:Adult; D000818:Animals; D000990:Antithrombin III / Q000032:analysis; D000997:Antivenins / Q000627:therapeutic use; D001780:Blood Coagulation Tests; D002648:Child; D004546:Elapid Venoms / Q000009:adverse effects* / Q000276:immunology; D017815:Elapidae; D005340:Fibrinogen / Q000032:analysis; D005342:Fibrinolysis / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D010447:Peptide Hydrolases / Q000032:analysis; D011516:Prothrombin / Q000096:biosynthesis*; D012909:Snake Bites / Q000097:blood* / Q000188:drug therapy
D000997:Antivenins; D004546:Elapid Venoms; C046193:antithrombin III-protease complex; D000990:Antithrombin III; D011516:Prothrombin; D005340:Fibrinogen; D010447:Peptide Hydrolases