Efficient extraction and sensitive radioimmunoassay for hCG in human urine.

A single-step procedure for extracting and concentrating hCG in 24-h urine samples was developed. The procedure involves adsorption chromatography with Vitachange. The hCG recovery was more than 90% compared with about 51% for the standard kaolin-acetone method. Nonspecific urinary protein concentration of extracts was also reduced. Thus, this method for concentration of urinary hCG with subsequent radioimmunoassay (RIA) using an antiserum against the unique carboxylterminal peptide of hCG beta subunit provides a sensitive and specific method for detecting hCG in urine.