The International and "NIH" units for thrombin--how do they compare?
The current International Standard (IS) for alpha-thrombin was established in 1991. It was related in unitage with the 1st IS for Thrombin established in 1975 and contains 100 IU of thrombin activity. The National Institute of Health (NIH) standard (Lot J) is in common use for the calibration of commercial thrombin reagents and this study reports on a comparison of the thrombin units defined by these 2 standards. This study has indicated that one "NIH" unit is equivalent to 1.1 to 1.3 IU of thrombin, depending on the influence of PEG in the assay. A unitage ratio figure of 1.15 was recommended following analysis of data obtained in the presence and absence of PEG in the comparative assays. This was confirmed by amidolytic assay data.
Gaffney
P J
PJ
National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, UK.
Edgell
T A
TA
D001780:Blood Coagulation Tests; D006801:Humans; D009316:National Institutes of Health (U.S.); D011092:Polyethylene Glycols; D012015:Reference Standards; D013917:Thrombin / Q000592:standards*; D014481:United States; D014944:World Health Organization
D011092:Polyethylene Glycols; D013917:Thrombin