Comparison of a modified microagglutination technique for HBsAg with the standard technique and a new RIA system.

A further modification of the standard RPHA technique (Hepatest, Wellcome Reagents) for the detection of HBsAg is described. This modification does not require a centrifugation step which is required by the other modifications that have been described previously and consequently takes a little longer to perform. It does, however, retain the advantages of increased sensitivity and decreased costs which are also features of the other modifications. A series of 939 routine clinical specimens were used to evaluate the method described and to evaluate a new RIA kit for the detection of HBsAg (Hepatube, Wellcome Reagents). Of 53 specimens found to be positive for HBsAg by RIA, 50 (94% were detected by the modified Hepatest RPHA as opposed to 47 (89%) by the standard technique.