Monitoring treatments with unfractionated heparin: CTAD must be used instead of citrate as the anticoagulant solution when using partial-draw collection tubes. Results of a multicenter evaluation.
BACKGROUND
Sampling small volumes of blood may be necessary, particularly in pediatric patients, or in case of difficult or recurrent venipunctures.


METHODS
Routine hemostasis test results evaluated in partial- and full-draw evacuated polymer tubes obtained in 4 centers were compared.


RESULTS
No relevant discrepancy (Bland-Altman) was found between test results measured in partial- and full-draw tubes obtained from untreated patients and from patients on vitamin K-antagonist or low molecular weight heparin. In patients on unfractionated heparin (UFH), significantly lower anti-FXa activity [median=0.29IU/mL (range:0.04-1.15) vs. 0.39 (0.05-1.25), n=89, p<0.0001] and shorter aPTT were measured in partial-draw tubes. This discrepancy was likely to be related to the release of higher amounts of PF4 after increased platelet activation in partial-draw tubes. As CTAD is known to counteract platelet activation, we then collected blood into partial-draw CTAD tube and full-draw citrate tube. Both in patients on UFH and in untreated patients, no relevant difference could be demonstrated for all studied parameters (Bland-Altman), including aPTT and anti-FXa activity, even if analytical comparison showed significantly higher anti-FXa activity in partial-draw CTAD than in full-draw citrated tubes with a mean bias of 0.02 IU/mL, identical throughout the measuring range.


CONCLUSIONS
These results suggest that samples collected into partial-draw citrate tubes allow accurate routine coagulation testingin all patients but those requiring UFH assessment,in which their use led to a significant underestimation ofanticoagulation. In such cases, partial-draw tubes containing CTAD could be validly used to monitor heparin therapy as well as to perform routine coagulation testing.
Université Nice Sophia-Antipolis, Faculté de Médecine, CHU Saint Roch, Service d'Hématologie Biologique, Nice, France. toulon.p@chu-nice.fr
Pierre
P
Toulon
Liên
L
Abecassis
Motalib
M
Smahi
Catherine
C
Ternisien
D000241:Adenosine; D000925:Anticoagulants / Q000008:administration & dosage* / Q000097:blood*; D001780:Blood Coagulation Tests / Q000379:methods*; D001800:Blood Specimen Collection / Q000379:methods*; D002951:Citrates; D004176:Dipyridamole; D016903:Drug Monitoring / Q000379:methods*; D006493:Heparin / Q000008:administration & dosage* / Q000097:blood*; D006801:Humans; D013806:Theophylline
D000925:Anticoagulants; D002951:Citrates; D004176:Dipyridamole; D006493:Heparin; D013806:Theophylline; D000241:Adenosine