Prothrombin time in liver failure: Time, ratio, activity percentage, or international normalized ratio

SummaryThe prothrombin time (PT), obtained from a fresh normal plasma pool (FPP), is the basis both for the establishment of the 100% activity (normal plasma) and for the ratio calculation used in the International Normalized Ratio (INR) according to the recommendations of the ICSH/ICTH (6). Today the PT of lyophilized normal plasma pools are successfully used as reference for the assessment of samples in proficiency studies. However, a lack of comparability is to be recognized. Therefore the Committee of Hematology of the German Association of Diagnostics’ and Diagnostic Instruments’ Manufacturers (VDGH) decided to produce a candidate reference plasma (VDGH Reference Plasma) which was calibrated against fresh normal plasma pools in an international study.The basic calibration was performed by using the same certified BCR thromboplastin (BCT/099) by all participants. The endpoint was determined manually and by using the coagulometer Schnitger-Gross. In additional testings each participant used his own routine thromboplastins and methods. Calculating the ratio [PT VDGH Reference Plasma (sec)/PT fresh normal plasma pool (sec)] the VDGH Reference Plasma showed a deviation from the average fresh normal plasma pool of 1.05 both with the BCT/099 and with all thromboplastins. There were obtained some statistical differences between “plain” and “combined’’ (added factor V and fibrinogen) thromboplastins. No statistical difference was found between the different endpoint measurement methods (manual, mechanical, optical).In spite of these statistical deviations the VDGH Reference Plasma can be used for the standardization of the PT-normal (100%) value with different ratios for plain (1.06) and combined (1.02) thromboplastins. The manufacturers will use this VDGH Reference Plasma for the calibration of their commercially available calibration plasmas, which allows the user of such a material to calculate a calibrated 100% PT value.

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The effect of vitamin K on prothrombin time in critically ill patients: an observational registry study

Journal of Intensive Care ◽

10.1186/s40560-020-00517-5 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Sofia Dahlberg ◽

Ulf Schött ◽

Thomas Kander

Keyword(s):

Propensity Score ◽

Prothrombin Time ◽

Critically Ill ◽

Vitamin K ◽

Critically Ill Patients ◽

International Normalized Ratio ◽

University Hospital ◽

Red Blood Cell Transfusion ◽

Registry Study ◽

Exclusion Criteria

Abstract Background Previous studies have indicated that vitamin K deficiency is common in non-bleeding critically ill patients with slightly prolonged prothrombin time-international normalized ratio (PT-INR). It has never been investigated thoroughly whether the administration of vitamin K to these patients could affect their PT-INR. Therefore, the aim of this registry study was to evaluate changes in PT-INR in response to vitamin K in critically ill patients with PT-INR in the range of 1.3–1.9. Methods Patients admitted to a mixed 9-bed general intensive care unit at a University Hospital, between 2013 and 2019 (n = 4541) with a PT-INR between 1.3 and 1.9 at any time during the stay were identified. Patients who received vitamin K with appropriate sampling times for PT-INR and without exclusion criteria were matched with propensity score to patients from the same cohort who did not receive vitamin K (controls). PT-INR was measured at admission, within 12 h before vitamin K administration and 12–36 h following vitamin K administration. Exclusion criteria included pre-existing liver cirrhosis, any plasma or platelet transfusion, or > 1 unit red blood cell transfusion between PT-INR samplings. Results Propensity score matching resulted in two groups of patients with 129 patients in each group. PT-INR decreased in both groups (1.4 [1.3–1.4] in the vitamin K group and 1.4 [1.3–1.6] in the controls, p < 0.001 and p = 0.004, respectively). The decrease in PT-INR was slightly more pronounced in patients who received vitamin K (delta PT-INR − 0.10 [− 0.30 to − 0.10] in the vitamin K group and − 0.10 [− 0.20 to 0.10] in the controls, p = 0.01). Conclusion In critically ill patients with a PT-INR of 1.3–1.9, the administration of vitamin K resulted in a slightly larger decrease of PT-INR 12–36 h after administration compared to controls. Future studies should focus on identifying which patient populations may benefit most from vitamin K administration as well as whether vitamin K could be a better alternative than plasma or prothrombin complex concentrate to improve PT-INR before non-emergent invasive procedures.

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Response to Comment on “Expectation for Prediction Models for Prothrombin Time International Normalized Ratio Under Warfarinization for Safety Use in the Era of Precision Medicine”

Annals of Pharmacotherapy ◽

10.1177/10600280211018786 ◽

2021 ◽

pp. 106002802110187

Author(s):

Tatsuya Yagi

Keyword(s):

Prothrombin Time ◽

Precision Medicine ◽

Prediction Models ◽

International Normalized Ratio

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A modified international normalized ratio as an effective way of prothrombin time standardization in hepatology

Hepatology ◽

10.1002/hep.21680 ◽

2007 ◽

Vol 46 (2) ◽

pp. 528-534 ◽

Cited By ~ 94

Author(s):

Laurent Bellest ◽

Valérie Eschwège ◽

Raoul Poupon ◽

Olivier Chazouillères ◽

Annie Robert

Keyword(s):

Prothrombin Time ◽

International Normalized Ratio

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Outpatient Use of a Portable International Normalized Ratio/Prothrombin Time Monitor

Southern Medical Journal ◽

10.1097/00007611-199402000-00012 ◽

1994 ◽

Vol 87 (2) ◽

pp. 206-210 ◽

Cited By ~ 10

Author(s):

RICHARD H. WHITE ◽

DANIEL M. BECKER ◽

MICHAEL G. GUNTHER-MAHER

Keyword(s):

Prothrombin Time ◽

International Normalized Ratio

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Predictive Value of Age-Bilirubin-International Normalized Ratio-Creatinine Score in Short-Term Survival of Acute-on-Chronic Hepatitis B Liver Failure

Cellular Physiology and Biochemistry ◽

10.1159/000495904 ◽

2018 ◽

Vol 51 (5) ◽

pp. 2484-2495 ◽

Cited By ~ 2

Author(s):

Liang Chen ◽

Jun Zheng ◽

Jianye Cai ◽

Yusheng Jie ◽

Yingcai Zhang ◽

...

Keyword(s):

Risk Factors ◽

Chronic Hepatitis ◽

Hepatitis B ◽

Liver Failure ◽

International Normalized Ratio ◽

Meld Score ◽

Short Term ◽

Term Survival ◽

Training Cohort ◽

Short Term Survival

Background/Aims: The age-bilirubin-international normalized ratio-creatinine (ABIC) score, which is a predictive model commonly used for alcoholic hepatitis, has not yet been studied in acute-on-chronic hepatitis B liver failure (HBV-ACLF). We aimed to investigate the predictive value of the ABIC score in patients with HBV-ACLF. Methods: This retrospective study involved 398 patients diagnosed with HBV-ACLF, who were divided into a training cohort of 305 patients and a validation cohort of 93 patients. Univariate and multivariate Cox regression models were used to determine risk factors for mortality. Area under the receiver operating characteristic curve (AUC) was calculated to estimate and compare the predictive values of different prognostic scores. Results: The ABIC score was significantly higher in the death group of the training cohort than in its survival group. Independent risk factors for mortality identified by multivariate Cox analysis included blood urea nitrogen, ABIC score, and Chronic Liver Failure Consortium Organ Failure (CLIF-C OF) score. For predicting 1- and 3-month mortality, AUC was higher for the ABIC score than for the Model for End-stage Liver Diseases (MELD) score (0.732 vs. 0.653, P < 0.05, 0.695 vs. 0.619, P < 0.05, respectively), CLIF-C OF score (0.693, P=0.353, 0.656, P=0.341, respectively), and Child-Pugh score (0.675, P=0.189, 0.656, P=0.300, Respectively). Patients with ABIC score > 9.44 had reduced 1- and 3-month survival rates. Conclusion: ABIC score is superior to MELD score in predicting short-term survival in HBV-ACLF patients. ABIC score > 9.44 predicts high short-term mortality risk in HBV-ACLF patients.

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