Preanalytical variables and off-site blood collection: influences on the results of the prothrombin time/international normalized ratio test and implications for monitoring of oral anticoagulant therapy.

Author(s): van Geest-Daalderop JH, Mulder AB, Boonman-de Winter LJ, Hoekstra MM, van den Besselaar AM

Publication: Clin Chem, 2005, Vol. 51, Page 561-8

PubMed ID: 15650035 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of delayed centrifugation, centrifugation conditions (room temperature or 20°C), centrifugation duration (5 min or 10 min) and storage of plasma after centrifugation on PT in plasma. The study was conducted at 4 different centers, each using different collection tubes types and analysis methods.

   Summary of Findings:

   When tubes of whole blood were stored prior to centrifugation at 4 degrees C, room temperature, or 37 degrees C in center 2 which used Venoject tubes and analyzed with Recombiplastin the PT decreased progressively with storage, except for in tubes stored at 37 degrees C where the PT increased between 3-6 h and 6-24 h. In contrast, when centrifugation was delayed at Center 1 which used Monovette or plastic Vacutainer tubes and analyzed PT using HepatoQuick, no changes were observed in PT of specimens stored at room temperature, but PT increased in specimens stored for 24 h at 4 or 37 degrees C and decreased in specimens stored for 3 h at 37 degrees C. Interestingly, when specimens were stored at room temperature with agitation prior to centrifugation, all specimens, except those from center 2 stored for 3 h, showed significant increases in PT. In specimens from center 3, which used glass Vacutainers and analyzed PT with Symplastin, storage of blood with agitation prior to centrifugation resulted in progressive decreases in PT at 2-4 degrees C, a decrease in PT after 3 h at 37 degrees C, and an increase in PT after 24 h at 37 degrees C. After centrifugation, storage of plasma for up to 24 h prior to analysis using the conditions of center 2 had no effect on PT, but using center 1's conditions, PT was decreased when centrifuged specimens were stored for 3 or 6, but not 24 h prior to analysis. There were no significant differences between the PT of specimens centrifuged at a controlled temperature of 20 degrees C and those centrifuged without temperature control, and centrifugation time also had no effects on PT.

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Plasma

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Not specified

   Platform:

   Analyte	Technology Platform
   Morphology	Hematology/ auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	0.5-1 h 3 h 6 h 24 h
   Storage	Storage temperature	4-6 degrees C Room temperature 37 degrees C
   Storage	Type of storage container	Monovette or plastic vacutainer Venoject Glass vacutainer
   Biospecimen Aliquots and Components	Blood and blood products	Plasma Whole blood
   Storage	Storage conditions	Mechanical agitation No agitation
   Hematology/ auto analyzer Specific	Technology platform	Recombiplastin HepatoQuick Symplastin
   Biospecimen Aliquots and Components	Centrifugation	Multiple temperatures compared Multiple durations compared Centrifugation delays investigated

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