Autosomal Dominant Polycystic Kidney Disease and Idiopathic Arginine Vasopressin Deficiency: A Peculiar Case Report of Accelerated Kidney Function Decline.

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic kidney disorder characterized by progressive cyst growth and kidney impairment. Arginine vasopressin deficiency (AVP-D) is a rare disorder resulting from reduced arginine vasopressin production, causing polyuria and thirst. The coexistence of ADPKD and AVP-D is rarely documented in the literature. We report what may be the first documented case of a patient diagnosed with ADPKD and idiopathic AVP-D. Initially managed with intranasal desmopressin, the patient's kidney function declined earlier than expected based on her ADPKD, progressing to kidney failure at a low total kidney volume (836 mL). This paradoxical outcome suggests that while AVP-D may have initially slowed cyst growth, her uncontrolled AVP-D likely contributed to kidney function decline, presumably due to recurrent volume depletion and acute kidney injuries. This case highlights the need for individualized AVP-D management in ADPKD patients and reiterates AVP's role in the complex pathophysiology of ADPKD progression.