Table of ContentsDefinition / general
Cite this page: Parsons J. International sensitivity index (ISI). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/coagulationISI.html. Accessed May 29th, 2020.
Definition / general
- Measure of sensitivity of particular PT reagent - determined by manufacturer
- Used to resolve interlaboratory variations in PT (Arch Pathol Lab Med 2004;128:308, J Clin Pathol 2003;56:114)
- Different PT reagents have different sensitivities to factor deficiencies
- High ISI (3.0) means insensitive reagent vs. low ISI (1.0) means sensitive reagent
- Labs should use reagents with an ISI of 1.0 to 1.5, if possible