Quality control of the latex-fixation test.

Standardization of the latex-fixation test for the detection of rheumatoid factor may be achieved by the preparation of a standard reference serum. A number of guidelines for the quality control of precision and sensitivity of the test are suggested. In the use of dilution procedures, a 0.1 log10 or a 0.05 log10 difference between tubes is employed. The end point is defined and titer expressed in terms of a final dilution represented by the amount of antigen-antibody added. For statistical purposes all serologic data are geometrically expressed. Commercial kits may be standardized in terms of minimum detectable units and normalized for titer and unit values to enable laboratories to compare results.