Stability of human chorionic gonadotropin and its alpha subunit in human blood

The stability of human chorionic gonadotropin (hCG) and its alpha-subunit in whole blood, plasma, and serum under a variety of sample handling conditions commonly encountered in clinics, hospital wards, physician's offices, and clinical service laboratories was investigated with the use of radioreceptor assay, radioimmunoassays, as well as hormone integrity determinations. The results clearly demonstrate that hCG and its alpha-subunit are stable in unfrozen whole blood, plasma, and serum for at least 6 days and in frozen plasma and serum samples for at least 6 months. Repeated freezing and thawing of the samples during this period had no effect. Separation of plasma or serum from erythrocytes is not needed for at least 12 hours. Hemolysis in samples resulted in a 20% to 30% decrease in hCG and its alpha-subunit levels, which may be attributable to sample dilution.