Different types of postoperative diabetes insipidus and the relation to basal and stimulated serum prolactin levels in patients with hypothalamo-hypophyseal tumorous lesions.

To evaluate the interrelationships between anterior pituitary function and the antidiuretic system in patients harbouring hypothalamo-hypophyseal tumorous lesions, combined anterior pituitary stimulation tests were performed in the pre (n = 192 patients) and postoperative (n = 151 patients) state. Basal and stimulated plasma antidiuretic hormone, serum as well as urinary osmolality and diuresis were analyzed to determine the residual functional capacity of the antidiuretic system. In 106 patients with non-prolactin (PRL) secreting tumours basal and stimulated PRL secretion of the residual anterior pituitary was studied pre- and postoperatively. It was found that in the preoperative state latent (n = 12 patients) or manifest (n = 10 patients) types of diabetes insipidus (DI) were related to a significant decrease of maximal stimulated levels of thyroid stimulating hormone as well as basal and maximal stimulated levels of follicle stimulating hormone relative to patients without DI. In the postoperative state DI lasting longer than 10 days (n = 51 patients) was associated with decreased basal and maximal stimulated concentrations of cortisol, luteinizing and follicle stimulating hormone, whereas basal and maximal stimulated levels of PRL were significantly increased compared to those patients without DI (n = 61 patients). Decompression (n = 65 procedures) via the transnasal route was related with a lower frequency of the more severe types of DI (n = 7 patients) and a significant decrease of basal and maximal PRL levels in patients with non-PRL secreting tumours. The transcranial approach (n = 86 procedures) caused a higher rate of severe DI types (n = 33 patients) and an increase of PRL secretion from the residual anterior pituitary lobe. Patients without DI or DI of mild severity (n = 50), as a group, had a significant decrease of basal and maximal PRL levels compared with preoperative values (preoperative: basal = 14.3 +/- 1.5 ng/ml, max = 31.4 +/- 1.5 ng/ml, postoperative: basal = 9.6 +/- 1.1 ng/ml, max = 24.9 +/- 2.9 ng/ml). In patients with severer degrees of DI (n = 40) PRL levels were significantly increased, respectively (preoperative: basal = 15.3 +/- 3.1 ng/ml, max = 23.9 +/- 7.6 ng/ml, postoperative: basal = 19.7 +/- 3.4 ng/ml, max = 38.6 +/- 7.9 ng/ml). It was concluded that in the surgical treatment of non-PRL secreting hypothalamo-hypophyseal lesions the results of early postoperative assessment of basal and stimulated PRL levels may predict the type of postoperative DI.(ABSTRACT TRUNCATED AT 400 WORDS)