Antithrombin III estimation immunological versus chromogenic substrate in bilharzial liver fibrosis

ABSTRACT

Fourty one patients with bilharzial liver fibrosis were investigated for antithrombin III [AT III] by chromogenic substrate method versus radial immuno-diffusion method. A control group of sixteen healthy young adults was also assayed for comparison. There was a significant AT III deficiency in bilharzial liver patients, mainly due to defective synthetic ability of the liver and low grade DIC. A significant positive correlation was found between results of ATIII antigen as measured by chromogenic substrate method. However the antigen values were significantly higher than the activity, possibly due to presence of abnormal nonfunctioning antigen molecules. By comparing the two methods, it was found that the technique of radial immunodiffusion method is much easier with single step, thus it is more precise with less coefficient of variation. However, the chromogenic substrate method offers many advantages. It is more sensitive than the immunodiffusion method and it takes very short time with a relative technical simplicity. Both methods are of equal high specificity and show good correlation between expected and observed results. Cost study showed that both methods were nearly equal. Although the chromogenic substrate method needs a special equipment, however the low reagent consumption reduces much the cost per assay