Abstract
In clinical field, estimation of fibrinogen is important examination for the diagnosis of promyelitic leukemia, hemophilia and hypofibrinogenemia etc.
There are several methods for this assay: 1) turbidimetry, 2) viscosimetry, 3) using formed fibrin clot, a) weighing method, b) colornnetry by biuret reagent3 c) by phenol reagent, d) and by tyrosine reaction, e) ultraviolet absorption method (UV method).
In this present paper author tried to establish ultramicro method of fibrinogen determination using 0.02-0.05ml plasma by ammonium sulfate turbidimetry which is the most simple one among the foregoing methods. These results were compared with those obtaind by specific UV method.
Method
Ammonium sulfate turbidimetry In original method, the precipitant is added to 0.5ml of blood plasma and thus formed turbidity was examined by turbidimetry. In the ultramicro method, all the process was carried out on a scale of 1/10 original method.
UV method
To 1.0ml of plasma, thrombin was added in the presence of buffer solution, thus formed fibrin clot was washed with saline solution and then dissolved in urea solution. This absorbancy was read at 280mu.
Conclusion
The author tried to establish an ultramicro method of ammonia sulfate turbidimetry, and the result was compared with that of UV method which seemed specific. The results are: 1) turbidity is not influenced by the temperature, 2) turbidity should be measured 3 to 6 minutes after an addition of specimen reagent, 3) the result was same by the ultramicro method so far as the proportion of plasma and reagent was not changed, 4) the determinations were compared with UV method in seven clinical cases, and it was found that the latter was 20% less than the former.
Considering from these results, fibrinogen turbidimetry mentioned in the above has some problems in specificity and reproducibility, compared with UV method. However, in a laboratory which is not equipped with ultraviolet adsorption spectrophotometer, fibrinogen assay is available using this method and in addition to this it can be carried out on a ultramicro scale.
