Influence of circulating D-dimer levels on assays of fibrinogen

The influence of circulating D-dimer levels on two different assays for fibrinogen was studied in 31 normal female subjects, 18 late pregnant subjects, 8 male subjects with acute myocardial infarction (AMI) and 9 subjects with unstable angina (UA). Both functional and chemical methods for fibrinogen showed significant correlation (r = 0.8171; P < 0.001). However, values for fibrinogen were significantly lower using the functional method in normal females, AMI and UA patients with mean (SD) ratios of 0.88 (0.11), 0.78 (0.17) and 0.84 (0.09) respectively as compared to the chemical assay method. In late pregnancy this was not observed with a mean ratio of 1.09 (0.22) obtained between the two methods. The D-dimer level in normal subjects was mean 194 (95.3) ng/ml whilst in late pregnancy, in AMI and UA, the levels were significantly elevated at 1093 (1034), 382 (216) and 1056 (708) ng/ml respectively. Significant correlation between fibrinogen and D-dimer levels was observed only in AMI and UA patients but not in late pregnancy. In 3 patients with AMI undergoing thrombolysis, no functional fibrinogen was detectable for the first 12 h following intravenous streptokinase (SK) despite the presence of chemically detectable fibrinogen with values of 13% to 30% of pre-treatment levels and evidenced by lytic states evaluated by thromboelastography (TEG). Grossly elevated D-dimer levels of between 25 x 10(3) and over 100 x 10(3) ng/ml were present during this time. Functional fibrinogen was detectable by 24 h following SK therapy but its level in relation to fibrinogen detected chemically remained depressed.(ABSTRACT TRUNCATED AT 250 WORDS)