Ectopic production of human chorionic gonadotropin (hCG) by neoplasms: the value of measurements of immunoreactive hCG in the urine as a screening procedure

Abstract

Immunoreactive human Chorionic Gonadotropin (hCG) was measured in serum and urine extracts from patients with malignant disease using a radioimmunoassay that detects efficiently hCG and its betasubunit. Of the 70 patients examined, 12 (17.1%) were positive for hCG in serum and 31 44.3%) in urine. Eleven patients who were positive in serum were also positive in urine; 20 patients (28.6%) were positive only in urine. Sephadex G-100 chromatography of urine from two serum-negative and urine-positive patients showed that the hCG immunoreactive material in the urine of these patients was mostly a molecular species smaller than hCG and hCG-beta. The nature of this molecule(s) is unknown and is called here metabolite(s) "X" of hCG-beta. The urine of 2 patients who where positive for hCG in both serum and urine contained considerable amount of metabolite(s) "X" as well as the native hCG-beta subunit, which was present also in the serum of these 2 patients. The metabolite(s) "X" was also shown by chromatography in the urine of a pregnant woman. It is concluded that the ectopic production of hCG is found more than twice as frequently in urine as compared to when serum alone is examined. The urine of serum-negative tumor patients can be positive for hCG because of the presence in it of the metabolite(s) "X" of hCG-beta or hCG which presumably circulates in the blood of these patients at non-detectable levels.