Establishing a normal reference range for thromboelastography in North Indian healthy volunteers.
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Date
2014-01
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Abstract
Background: Thromboelastography (TEG) is relatively recent assay to analyze the
coagulation state of a blood sample, providing a continuous visualization of physical
changes occurring during blood coagulation. There is a paucity of published
literature on assessment of coagulation status using TEG in Indian population.
Aim: The primary aim of the following study is to establish normal reference values
for TEG in North Indian healthy volunteers and secondary aim is to compare them
with conventional plasma-based routine coagulation tests and the manufacturers
reference range. Materials and Methods: A total of 200 healthy volunteers
comprised of 100 males and 100 females of age groups between 20 and 50 years,
were enrolled over a period of 1 year, i.e., 2011-2012. Thromboelastometry (TEM)
was performed on TEM-A automated thromboelastometer (Framar Biomedica,
Rome, Italy), using whole blood non-additive (360 μl). TEG parameters analyzed
were r-time, k-time, α-angle, maximal amplitude (MA). Prothrombin time (PT),
activated partial thromboplastin time (aPTT) and platelet count was performed for
all volunteers. The 95% reference range was calculated as (mean-1.96 standard
deviation [SD]) to (mean + 1.96 SD). Results: Our reference values for 95% of 200
volunteers were r-time: 1.8-14.2 min, k-time: 0.7-7.3 min, α-angle: 27.3-72.3° and
MA: 32.1-87.9 mm. Maximum clot strength was higher in women compared with
men, however statistically insignifi cant. Overall 14.5% (29/200) of the volunteers
had at least one abnormal parameter while 74% (149/200) had deranged TEG
values using the manufacturer’s reference range. Statistically signifi cant variation
was seen in r-time for 84.8% (P < 0.001), for k-time, in 87.1% (P < 0.001), for
α-angle in 83.7% (P < 0.001) and for MA in 84% (P < 0.001), between the
manufacturer and our reference range. Conclusion: The effi cacy of classical
coagulation test has been well-established; on the contrary TEG is a fairly recent
assay and its utility for patient management remains to be demonstrated. We
observed TEG to be oversensitive in determining coagulopathy where there is no
clinical presentation. The manufacturer’s reference values may not be appropriate
for different ethnicity. TEG may give an overall representation of hemostasis;
however, it cannot replace the conventional coagulation tests. We recommend the
determination of normal TEG values by each laboratory for their target population.
Description
Keywords
Normal range, thromboelastography, volunteers
Citation
Subramanian Arulselvi, Albert Venencia, Saxena Renu, Agrawal Deepak, Pandey Ravindra Mohan. Establishing a normal reference range for thromboelastography in North Indian healthy volunteers. Indian Journal of Pathology & Microbiology. 2014 Jan-Mar 57 (1): 43-50.