Diagnostic reliability of simultaneous measurements of beta human chorionic gonadotropin and pregnancy-specific beta-1-glycoprotein in serum of patients with trophoblastic disease.

Serum levels for beta-human chorionic gonadotropin (beta-hCG) and pregnancy-specific beta 1-glycoprotein (SP1) in patients with trophoblastic disease were measured by radioimmunoassay and enzyme-linked immunosorbent assay. The beta-hCG:SP1 ratios were below 1.0 in all 22 cases of complete hydatidiform mole and in 8 of 9 cases of partial hydatidiform mole. Two (10.5%) of 19 cases of invasive mole involving metastasis had ratios that rose above 1.0 during chemotherapy. Ratios ranged from 1.6 to 29 in 11 of 15 cases of choriocarcinoma before chemotherapy. The remaining 4 cases, diagnosed within 3 months of antecedent pregnancy, had ratios below 0.99. Thus, the difference between choriocarcinoma and nonchoriocarcinoma beta-hCG:SP1 ratios may be due to trophoblastic differentiation based on the developmental stage and with trophoblast age, or due to the mass and potential activity of trophoblastic cells.