Radioimmunoassay of diethylstilbestrol in plasma of patients with prostatic carcinoma.

A method for the radioimmunoassay of diethylstilbestrol (DES) was established and it was used to measure the plasma concentration of DES in patients with prostatic carcinoma receiving intravenous drip infusion of 500 mg of diethylstilbestrol diphosphate (DES-DP). The sensitivity of this assay system was 40 pg per tube, with a recovery of 98%. The cross reactivity of the anti-DES antibody with estradiol, testosterone, and ethynylestradiol was less than 0.01% of DES, and that with DES-DP was 0.7%. In patients with prostatic carcinoma, plasma DES concentration at 6 and 24 hr after was declined to 10.2% and 4.4% of the level at the termination of intravenous administration of DES-DP, respectively; however, the concentration in patients with renal dysfunction was higher than that in ones with normal renal function.