Prolactin dynamics following transsphenoidal hypophysectomy for metastatic carcinoma of the breast

In nine patients who had undergone trans‐sphenoidal hypophysectomy, prolactin dynamics were studied with intravenous thyrotropin releasing hormone (TRH). Residual prolactin secretory reserve was demonstrated in seven. Five patients were TRH tested both before and after trans‐sphenoidal hypophysectomy. Hypophysectomy did not alter base line prolactin concentration but did decrease prolactin response to TRH from 55 ng/ml to 21 ng/ml (p > 0.001). Post‐hypophysectomy L‐Dopa suppressed baseline prolactin concentrations to undetectable levels. There was no correlation between alterations in prolactin dynamics and tumor response to hypophysectomy. Trans‐sphenoidal hypophysectomy is not effective in ablating prolactin secretion and serious doubts are raised about the role of altered prolactin dynamics in inducing breast cancer remission.