Effect of magnesium on fibrin formation from lower molecular weight (LMW) fibrinogen

Fibrinogen circulating in human blood is comprised of high molecular weight (HMW) and lower molecular weight (LMW) fractions. As previously documented by means of SDS-polyacrylamide gel electrophoresis (PAGE), LMW fraction was significantly increased in patients with cardiovascular disease and with diabetes mellitus (DM). We have recently observed that the values of fibrinogen measured by thrombin clotting time (the method of Clauss) were consistently lower in EDTA plasma than those obtained with citrated plasma. However, supplementation of EDTA plasma with magnesium (Mg) ions gave comparable results. In this study we documented by SDS-PAGE that fibrin formed with thrombin alone in EDTA plasma originated from HMW fibrinogen, whereas that formed after addition of Mg was derived from LMW fibrinogen. Thus, measurement of thrombin clotting time in EDTA plasma with and without Mg may serve as a quick method for the determination of HMW and LMW fibrinogens in human blood. Preliminary result obtained with this new method revealed that LMW fibrinogen was significantly increased in DM patients. We have therefore concluded that measurement of this fraction of fibrinogen may prove to be of clinical diagnostic significance.