Assessment of the influence of citrate concentration on the International Normalized Ratio (INR) determined with twelve reagent-instrument combinations.

Author(s): Chantarangkul V, Tripodi A, Clerici M, Negri B, Mannucci PM

Publication: Thromb Haemost, 1998, Vol. 80, Page 258-62

PubMed ID: 9716149 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 trisodium citrate concentration and instrument/reagent combination on PT in plasma specimens from normal volunteers and patients on oral anticoagulant therapy.

   Summary of Findings:

   Mean PTs were longer for specimens collected in tubes containing 129 mM citrate compared to those collected in tubes containing 105 mM citrate, regardless of instrument, thromboplastin reagent, or whether the specimen was from a healthy volunteer or a patient on oral anticoagulant therapy, although the range of percentage differences was larger for patients on oral anticoagulant therapy than healthy volunteers. There were significant differences in the PT ratios (patient PT/mean PT of 20 normal volunteers) between the two citrate concentrations for the following instrument/reagent combinations: manual/Innovin, manual/PT HS, ACL 300R/ Recombiplastin, ACL 300R/Innovin, ACL 300R/PT HS, Koagulab/Neoplastin plus, Koagulab/Innovin, and Koagulab/PT HS. The other instrument/reagent combinations did not result in significant differences in PT ratios between the two citrate concentrations. For the BCT/441 reagent used only with the manual tilt tube technique, the ISI was not significantly influenced by citrate concentration, however, for the other 4 reagents, ISI values were greater when calibration was done using specimens collected in 105 mM citrate rather than 129 mM citrate, and the largest differences were observed for Innovin and PT HS, regardless of technique/instrument. Using the inappropriate ISI value to calculate INR values (i.e. ISI-105 to calculate INR-129) rather than the appropriate ISI led to significantly different INR values, which were clinically significant for specimens with an INR of 4.5 for all instrument/reagent combinations tested. Further, the effects of citrate concentration were even more pronounced if the ISI generated with the manual technique was used to determine INR values using the 4 instruments.

   Biospecimens

   • Bodily Fluid - Plasma
   • Bodily Fluid - Blood

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Normal
   • Not specified

   Platform:

   Analyte	Technology Platform
   Morphology	Hematology/ auto analyzer
   Morphology	Macroscopic observation

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Preaquisition	Other drugs	None Oral anticoagulant therapy
   Hematology/ auto analyzer Specific	Technology platform	Manual tilt tube technique ACL 300R Koagulab Chromo
   Hematology/ auto analyzer Specific	Reaction solution	Recombiplastin Neoplastin plus Innovin PT HS
   Macroscopic observation Specific	Reaction solution	BCT/441 Recombiplastin Neoplastin plus Innovin PT HS
   Biospecimen Acquisition	Anticoagulant	Sodium citrate Multiple concentrations evaluated

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