Frozen/Thawed Samples Can Replace Fresh Samples for Assignment of ISI to Secondary Thromboplastin Standards for Multiple Reagent/Instrument Combinations: Data to Support Possible Revision of WHO Guidelines.
Int J Lab Hematol
; 2024 Sep 12.
Article
en En
| MEDLINE
| ID: mdl-39266008
ABSTRACT
BACKGROUND:
Calibration of thromboplastins is required for accurate calculation of the international normalised ratio (INR). Accurate INR results are required for optimal dosing of vitamin K antagonists. Decreases in vitamin K antagonist usage have made the recruitment of sample sets for international sensitivity index (ISI) calibrations more difficult. A possible solution to this would be to allow the use of frozen-thawed samples in place of fresh plasmas in the calibration of secondary standards.OBJECTIVES:
We investigated the effect of freezing and thawing samples before usage in ISI calibrations of secondary standards.METHODS:
Multiple reagent/instruments were tested to identify the degree of difference between a fresh sample ISI calibration and one performed on frozen-thawed samples. Where possible, the two ISI calibrations were performed on the same sample set. Alternatively, a separate set of samples from different patients was used.RESULTS:
The difference in ISI values was <3% for those datasets where the same samples were used, and <6% for those datasets where two sample sets were used. Additionally, other parameters required for a valid ISI calibration showed only minor differences-some calibrations showed fewer outliers in the frozen-thawed datasets. Mean normal prothrombin time for the international reference thromboplastins was <3.5% different across four different calibrations (two for rabbit thromboplastin and two for recombinant human thromboplastin).CONCLUSIONS:
This modification to the WHO guidelines would facilitate the recruitment of test plasmas in advance of calibration solving the problem of requiring availability of fresh patient samples with a range of INRs in a 5-h window. TRIAL REGISTRATION Not a part of any clinical trial.
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Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Int J Lab Hematol
Asunto de la revista:
HEMATOLOGIA
Año:
2024
Tipo del documento:
Article
País de afiliación:
Reino Unido