Detecting and monitoring trophoblastic disease. New perspectives on measuring human chorionic gonadotropin levels.

The human chorionic gonadotropin (hCG) molecules in trophoblastic disease serum and urine samples are more heterogeneous, or degraded, than those in pregnancy samples. HCG immunoassays, particularly some of the new multiantibody sandwich tests, are designed primarily for pregnancy application and do not necessarily detect the degraded molecules found in trophoblastic disease samples. This leads to erroneous results and possibly false diagnoses. Care is needed in choosing the hCG test for monitoring trophoblastic disease.