PITUITARY FUNCTION AFTER YTTRIUM IMPLANTS AS MEASURED BY PLASMA GROWTH HORMONE LEVELS

SUMMARY Plasma growth hormone (GH) levels during insulin hypoglycaemia were measured in 30 women with implants of 90Y in the pituitary for advanced breast cancer. There was evidence of continued pituitary activity in six patients (20%), the rise in plasma GH level being greater than 4 ng/ml during hypoglycaemia. Thirteen patients (43%) were regarded as having complete ablations because they had no GH response and a fasting level of less than 4 ng/ml. In the remaining 11 patients (37%) there was no rise in the GH level during hypoglycaemia, but there were significant fasting levels. From the post-mortem evidence it was concluded that these patients also had adequate ablations. This test is shown to be of more value in estimating residual pituitary function than routine tests of thyroid or adrenal function.