An evaluation of turbidimetric technics for estimation of plasma fibrinogen.

Studies on precipitation and turbidimetric methods for fibrinogen determination employing Na2SO3, Na2SO4, (NH4) 2S04 and a mixture of phosphate salts are presented. Optimal reaction conditions for these technics have been verified. The amounts of plasma fibrinogen precipitated by the sulfite and phosphate methods are in closer agreement than either are with values obtained by the (NH4)2S04 and Na2SO4 precipitation technics. It has been determined that the degree of turbidity produced by salt fractionation is not a reliable index of the amount of fibrinogen present. The measurement of fibrinogen concentration of turbidity produced by the various fractionation agents does not appear to be precise enough for the quantitative measurement of this protein.