THROMBOSIS RESEARCH 64; 33-43,199l 0049-3848/91 $3.00 + .OO Printed in the USA. Copyright (c) 1991 Pergamon Press pk. All rights reserved.
A NEW ASSAY FOR BTHROMBGGLOBULIN
P. Hjemdahl, C. Pemeby, E. Theodorsson, N. Egberg and P.T. Larsson Department of Clinical Pharmacology, Department of Clinical Chemistry and Coagulation Laboratory, Karolinska Hospital, and Department of Pharmacology, Kamlinska Institute, S-104 01 Stockholm, Sweden (Received
in revised form 11.7.1991
by Editor B. Hessel)
Measurements of B-thromboglobulin (BTG) excretion in urine may be of value for “field” studies and due to problems with sampling artifacts for BTG in plasma. Previous studies have used a radioimmunoassay designed for plasma without characterizing the “BTG” immunoreactivity in urine. We describe modifications of the assay which increase its sensitivity and a sample work-up procedure using Sephadex G-25M columns separating high molecular weight (I-IMW) components (presumably intact l3TG) from low molecular weight (LMW) immunoreactivity (i.e. DTG fragments and/or non-specific interferences). The sensitivity of the assay (with 2.5 ml sample) is cl2 pg/ml HMW BTG. Inter- and intraassay coefficients of variation were 7-104. Only 33 (range 5-75)s of BTG immunoreactivity in urine represented HMW BTG. LMW immunoreactivity may be related to salt and other non-specific influences in the sample. Recoveries of BTG were quite variable (g-1001) in unextracted urines, but high and reproducible (80+2%) in the HMW fraction. Thus, nonspecific interferences with BTG measurements in certain urines are overcome by the separation step. Using Sephadex fractionation l3TG immunoreactivities in night urines (n=15) were: uH3 pg/ml in the HMW fraction, 70&8 pg/ml in the LMW fraction, and 85flO pg/ml by direct assay. HMW BTG increased in daytime samples (to 3of5 pg/ml; p