Prothrombin time ratio is reduced by magnesium contamination in evacuated blood collection tubes.

Author(s): van den Besselaar AM, van Dam W, Sturk A, Bertina RM

Publication: Thromb Haemost, 2001, Vol. 85, Page 647-50

PubMed ID: 11341499 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 Mg contamination on PT in blood and plasma specimens from patients on oral anticoagulants and normal controls. Plasma was dialyzed to remove citrate and endogenous ions prior to experimental addition of citrate and magnesium.

   Summary of Findings:

   At concentrations found in citrate Vacutainer tubes and stoppers, Mg significantly decreased PT in normal plasma and in plasma from patients on oral anticoagulants. However, the effect of Mg was greater in plasma from patients on oral anticoagulants and when plasma contained citrate. Because the effect of Mg was greater in patients on oral anticoagulants, increasing Mg concentration resulted in decreased PT-ratios and INR. When blood specimens were collected in freshly prepared citrate without magnesium, or in citrate with magnesium added to mimic levels in Vacutainer tubes, a 0.9-6.6% decrease in INR was found.

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Plasma

   Preservative Types

   • Frozen

   Diagnoses:

   • Not specified
   • Normal

   Platform:

   Analyte	Technology Platform
   Morphology	Hematology/ auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Preaquisition	Other drugs	None Oral anticoagulants
   Biospecimen Acquisition	Anticoagulant	Sodium citrate None
   Biospecimen Aliquots and Components	Blood and blood products	Whole blood Plasma
   Preaquisition	Biomarker level	0.2 mmol/L Mg 0.5 mmol/L Mg 1.0 mmol/L Mg 2.0 mmol/L Mg

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