Open AccessArtifactual Prolongation of the Activated Partial Thromboplastin Time Associated With Hemoconcentration in Dogs
Author(s) -
O'Brien Susan R.,
Sellers Teresa S.,
Meyer Dennis J.
Publication year - 1995
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/j.1939-1676.1995.tb03291.x
Subject(s) - partial thromboplastin time , medicine , hematocrit , hemoconcentration , prothrombin time , anesthesia , anticoagulant , thromboplastin , whole blood , platelet , gastroenterology , coagulation
An inappropriate blood‐to‐anticoagulant ratio can cause an artifactual prolongation of the activated partial thromboplastin time (APTT) and prothrombin time (PT). In a drug safety study in dogs, we observed a 4‐to 5‐second increase in the APTT from baseline coincident with increased hematocrit values (56% to 65%) secondary to drug‐induced vomiting and diarrhea. The PT and platelet counts were unchanged, and there was no clinical evidence of bleeding associated with venipuncture. Although we were unable to sample the same dogs to investigate the possible effect of hemoconcentration on the prolonged APTT, the question was addressed by an in vitro study. The hematocrit value for citrated blood samples collected from healthy beagle dogs was increased by the addition of aliquots of red blood cell/plasma mixtures in vitro while maintaining a 9:1 blood‐to‐anticoagulant ratio. There was a 2‐to 4‐second prolongation of the APTT associated with hematocrit values of 55% to 61 %, but the PT was not prolonged. Adjustment of the blood‐to‐anticoagulant ratio corrected the prolongation. This study emphasizes the important relationship of the blood‐to‐anticoagulant ratio when measuring coagulation tests in hemoconcentrated samples.