External quality control of determinations of tumour-associated antigens

Within the frame of the quality-control scheme of the German Society for Clinical Chemistry, an external quality-control survey for tumour-associated antigens was performed in November 1981. One hundred and twenty-one laboratories received two samples each of lyophilized human serum which was spiked with the analytes carcino-embryonic antigen (CEA), alpha-fetoprotein (AFP), and human chorionic gonadotropin (HCG). When giving the analytical values for HCG the participants could differentiate, depending on the antibodies used, between HCG, #betta#-HCG and HCG+#betta#-HCG. Seventy-five laboratories of the Federal Republic of Germany and 19 from other European countries sent their results for evaluation. The considerable interlaboratory imprecision of the analytical results cannot only be reduced to mistakes of the analysts. To a greater extent the varying analytical prerequisites of the different kits also had an effect. Furthermore, it must be assumed that many analysts have insufficient information about the reagents used. (author)