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TA Warr, BJ Warn-Cramer, LV Rao and SI Rapaport
Department of Medicine, University of California, San Diego, La Jolla.
An assay was standardized to measure extrinsic pathway inhibitor (EPI)
activity in human plasma. Variables that could potentially influence its
measurement were systematically examined. The coefficient of variation of
the assay was 6.3% for the same sample assayed on different days. The
linear regression line for a plot of observed v expected values of mixtures
of plasmas with different EPI levels was Y = 1.01X - 2.7%. Single samples
from 21 healthy adults under 60 years of age varied between 74% and 159% of
a pooled reference plasma. The plasma level of a given individual (eight
subjects) did not vary on repeat sampling over weeks to months. EPI
activity was significantly lower in plasma from umbilical cord blood (64.3%
+/- 12.7%, n = 16) than in plasma from adults. Mean EPI activity in adults
greater than or equal to 60 years of age was slightly but significantly
higher (112% +/- 16.8%, n = 23) than in adults less than 60 years of age
(97.2% +/- 19.0%, n = 21). EPI levels in the third trimester of pregnancy
were slightly higher than in nonpregnant women. Plasma EPI levels fell
slightly after surgical procedures that caused fibrinogen levels to rise,
which suggests that EPI is not an acute phase reactant. Administration of
1-desamino-8-d-arginine vasopressin (DDAVP) did not alter plasma EPI
levels. In two patients subjected to plasmapheresis and volume replacement
with albumin and isotonic saline, plasma EPI levels returned to one-half of
the levels before pheresis within about one day.
This article has been cited by other articles:
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| Copyright © 1989 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
