Radioreceptorassay of luteinizing hormone-human chorionic gonadotropin in urine: detection of the luteinizing hormone surge and pregnancy.

A radioreceptorassay of luteinizing hormone (LH)-human chorionic gonadotropin (hCG), using plasma membranes of bovine corpora lutea, has been extended to the detection of the midcycle LH peak and subsequent pregnancy in morning and 24-hour urine samples on days 10 to 12 following ovulatiobjects as determined by radioreceptorassay and radioimmunoassay were 45 ng and 20 ng/ml of urine, respectively; in 24-hour urine samples, mean levels of 39 ng and 17 ng of LH/ml, respectively, were found. A sustained rise in hCG was detected by the radioreceptorassay from 10 to 12 days after conception, and by day 15 the hCG levels were in the range of the midcycle LH range; this finding was confirmed by the radioimmunoassay of hCG.