Serum prolactin in patients with "functionless" chromophobe adenomas before and after therapy

The immunoreactive serum human prolactin (PRL) level was measured before and after intravenous administration of 500 mug of thyrotrophin-releasing hormone (TRH) in 11 patients with "functionless" chromophobe adenomas before and after surgery and after radiotherapy in 6 of these patients. The results were compared to other pituitary function tests. Two of the patients studied had recurrent disease after previous pituitary surgery and radiotherapy. Five patients had pituitary surgery through the transfrontal route, while 6 had adenoma removal via the transnasal transsplenoidal route. Before surgery, the serum PRL concentration was abnormally high in 4 patients, before and after TRH administration. It was normal in 6 and subnormal in 1 patient who had had previous therapy. Two of the patients studied showed high serum thyroid-stimulating hormone (TSH) levels in the presence of low serum T3 and T4 suggesting primary hypothyroidism with a secondary TSH-producing pituitary tumour. After surgery all patients showed a significant decrease of the serum PRL level. This contrasts with more variable results in the measurements of other pituitary hormones. Post-operative radiotherapy produced no significant additional change in serum PRL levels in 5 of the 6 patients measured 6 months to 4 years after radiotherapy. Five of the 6 patients who had adenoma removed via the transsphenoidal route required no cortisol replacement and 4 remained euthyroid, whereas all 5 patients after transfrontal surgery required both cortisol and thyroid hormone replacement. These results indicate: (1) that measurement of serum PRL levels at basal and after TRH administration in patients with "functionless" chromophobe adenomas before and after treatment may be the best index for evaluating the effect of therapy; (2) that adenoma removal may be followed by preservation of normal pituitary function, but this is more likely to occur if the transsphenoidal approach is used; and (3) that primary thyroid insufficiency may be associated with a pituitary adenoma.