Detection of incomplete ablation after yttrium-90 implantation of pituitary

Until recently the measurement of urinary gonadotrophins was the most reliable test for the detection of residual pituitary activity, especially in post-menopausal women. We have found it to be less sensitive than the metyrapone test. In the present series metyrapone was given in a dose of 750 mg. either four-hourly or six-hourly for 24 hours, both before and after implantation of the pituitary with 9 mc. of yttrium-90, and the pituitary-adrenal response assessed by measuring urinary 17-0H-CS. On testing with metyrapone, 9 out of 17 patients showed definite evidence of residual pituitary activity after implantation, but only three of these showed significant levels of urinary gonadotrophins.