title: Hump-nosed pit viper (Hypnale hypnale) envenoming causes mild coagulopathy with incomplete clotting factor consumption.
abstract: BACKGROUND
  Limited information exists on the coagulopathy caused by hump-nosed pit viper (Hypnale hypnale) envenoming.
  
  
  OBJECTIVE
  This study aimed to characterise the coagulopathy in hump-nosed pit viper bites by measuring laboratory clotting times and factor studies.
  
  
  METHODS
  Cases of hump-nosed pit viper envenoming were included from a prospective cohort study of Sri Lankan snake-bite patients. Patient age, sex, snake identification, time of bite and clinical effects were recorded. Patients did not receive anti-venom because no specific anti-venom to hump-nosed vipers exists. All patients received supportive care and serial 20-min whole blood clotting tests (WBCT20). The prothrombin time (PT), international normalised ratio (INR), activated partial thromboplastin time (aPTT), coagulation factors I, II, V, VII, VIII, IX and X, von Willebrand factor (vWF) antigen and D-Dimer concentrations were measured. The median of highest or lowest test result for each patient was reported with interquartile range (IQR). Results. There were 80 hump-nosed pit viper bites, median age was 37 years (IQR: 26-51 years) and 48 were male. The WBCT20 was positive in one patient. The median highest INR was 1.9 (1.5-2.2; Range: 1.3 to > 12) and median highest aPTT was 54 s (46-72 s; Range: 35-170 s). There was low fibrinogen [median: 1.3 g/L;1, -1.8 g/L; Range: < 0.2-2.9], low factor VIII levels [median: 23%; 16-37%] and low factor V levels [median: 43%; 23-74%]. D-Dimer concentrations [median: 3.4 mg/L; 2-7.4 mg/L] were slightly elevated. Factors II, VII and X and vWF antigen concentrations were normal.
  
  
  CONCLUSIONS
  Hump-nosed pit viper bites result in a mild coagulopathy which is usually not detected by a WBCT20. It is characterised by mild elevation of INR, low fibrinogen and Factors V and VIII which may be consistent with the venom containing a thrombin-like enzyme.
authors.affiliation: School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia.
authors.forename: K
authors.initials: K
authors.lastname: Maduwage
authors.forename: F E
authors.initials: FE
authors.lastname: Scorgie
authors.forename: A
authors.initials: A
authors.lastname: Silva
authors.forename: S
authors.initials: S
authors.lastname: Shahmy
authors.forename: F
authors.initials: F
authors.lastname: Mohamed
authors.forename: C
authors.initials: C
authors.lastname: Abeysinghe
authors.forename: H
authors.initials: H
authors.lastname: Karunathilake
authors.forename: L F
authors.initials: LF
authors.lastname: Lincz
authors.forename: C A
authors.initials: CA
authors.lastname: Gnanathasan
authors.forename: G K
authors.initials: GK
authors.lastname: Isbister
mesh_terms: D000328:Adult; D000818:Animals; D015415:Biomarkers / Q000097:blood; D001777:Blood Coagulation; D001778:Blood Coagulation Disorders / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D001779:Blood Coagulation Factors / Q000378:metabolism*; D003435:Crotalid Venoms / Q000097:blood*; D015536:Down-Regulation; D005165:Factor V / Q000378:metabolism; D005169:Factor VIII / Q000378:metabolism; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011517:Prothrombin Time; D012909:Snake Bites / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D013188:Sri Lanka; D013997:Time Factors; D017819:Viperidae
chemical_list: D015415:Biomarkers; D001779:Blood Coagulation Factors; D003435:Crotalid Venoms; C078147:F8 protein, human; D005165:Factor V; D005169:Factor VIII; D005340:Fibrinogen