Autologous radioiodinated fibrinogen, simplified.

A method for the rapid preparation of radioiodinated autologous fibrinogen has been improved. Plasma is separated from cells by a single centrifugation. Fibrinogen is isolated in two salting-out steps at a 1:4 dilution of plasma and 22.5% saturated ammonium sulfate. Iodination is accomplished with chloramine T at a chloramine T-to-fibrinogen molar ratio of 12:1. Free iodide is removed by a single dilution and salting-out step at 29% saturated ammonium sulfate. Preparation time is about 1 hr; clottable radioactivity is 90-95%. Denaturation due to storage is undetectable at 6 weeks. Advantages of this procedure are (A) a short preparation time and (B) a purified autologous radioiodinated fibrinogen preparation.