[Anterio-hypophyseal function in central diabetes insipidus]

In our recent experience, the posttraumatic diabetes insipidus (PT.DI) and idiopathic (I.DI) are the most common forms of central diabetes insipidus (C.DI) in adult patients. The hypothalamo-pituitary function in these patients may be quite heterogeneous. We evaluated this aspect in 32 patients with different forms of C.DI (19 males and 13 females; aged 16-55 yrs): 12 with previous severe cranial or general trauma; 8 with CNS lesion due to Tuberculosis, Sarcoidosis, Histiocytosis X or to other pathogenic noxa (Secondary DI); 12 with idiopathic form. In all we measured ACTH, TSH, FSH, LH, PRL and target hormones (pl. cortisol, T3 T4, Testosterone) in baseline conditions with and without substitutive DDAVP therapy. In all cases the hormonal pattern was within the normal range. In several patients stimulation test with specific releasing factors (TRH, LHRH, oCRH) were carried out. Although basal anterior pituitary function is usually normal in patients with central DI (post-traumatic, idiopathic or secondary), an isolated subclinical secondary or tertiary hypothyroidism can be observed in some cases. Thus, a more accurate, periodical, and complete hormonal evaluation is indicated in some patients. The maintained response of ACTH to CRH (even increased after acute withdrawal therapy) indicated that AVP is not necessary to ensure normal function to the CRH-ACTH axis.