Background: Adult polycystic kidney disease (ADPKD), an autosomal dominantly inherited cause of ESRD, is often characterized by a relative renal tubular unresponsiveness to ADH. Polyuria, renal concentrating defects and generally elevated ADH levels, a form of nephrogenic diabetes insipidus (NDI) is often implicated. Thus, even late in stages of CKD, ADPKD patients often produce significant amounts of urine. Conversely, central diabetes insipidus (CDI), a clinical syndrome secondary to deficiency of ADH, also leads to production of large volumes of dilute urine, i.e. polyuria. It is widely believed that clinical CDI is masked in ESRD patients on dialysis, due to apparently obvious reasons. However, there have been published a few reports of the unmasking of polyuria secondary to previously existing CDI in ESRD patients, after kidney transplantation.
Material and Method: We report, to our knowledge, the first case of new-onset symptomatic CDI causing nocturnal polyuria in an ADPKD patient with ESRD, before now on hemodialysis. CDI symptoms were noted, months after an intracranial aneurysm clipping procedure that was complicated by intra-cranial hemorrhage. The 59-year old Caucasian woman responded moderately to desmopressin replacement therapy.
Results:
Conclusions: Several interesting pathobiologic implications of this case report are entertained.

Keywords: Kidney Failure, Chronic - complications, Intracranial Hemorrhages - complications, Female, Humans, Middle Aged, Diabetes Insipidus, Neurogenic - etiology, Polycystic Kidney, Autosomal Dominant - complications