Can Additional Water a Day Keep the Cysts Away, in Patients with Polycystic Kidney Disease?

Feasibility of Water Therapy for Slowing Autosomal Dominant Polycystic Kidney Disease Progression

Key Points

Water therapy in autosomal dominant polycystic kidney disease (ADPKD) reduces urine osmolality and serum copeptin level, a marker of vasopressin activity. Water therapy reduces the ADPKD kidney growth rate indicating it is slowing disease progression. Patients with ADPKD are less likely to report pain on water therapy.

Background

In animal models of autosomal dominant polycystic kidney disease (ADPKD), high water intake (HWI) decreases vasopressin secretion and slows disease progression, but the efficacy of HWI in human ADPKD is uncertain.

Methods

This exploratory, prospective, cross-over study of patients with ADPKD (N =7) evaluated the hypothesis that HWI slows the rate of increase in height-adjusted total kidney volume (ht-TKV; a biomarker for ADPKD progression) and reduces pain. Patients at high risk of ADPKD progression (i.e ., Mayo Imaging Classifications 1C/1D) were evaluated during 6 months of usual water intake (UWI), followed by 12 months of HWI calculated to reduce urine osmolality (Uosm) to <285 mOsm/kg. Measurements of Uosm, serum copeptin (secreted in equimolar amounts with vasopressin), magnetic resonance imaging measurements of ht-TKV, and pain survey responses were compared between HWI and UWI.

Results

During HWI, mean 24-hour Uosm decreased compared with UWI (428 [398–432] mOsm/kg versus 209 [190–223] mOsm/kg; P = 0.01), indicating adherence to the protocol. Decreases during HWI also occurred in levels of serum copeptin (5.8±2.0 to 4.2±1.6 pmol/L; P = 0.03), annualized rate of increase in ht-TKV (6.8% [5.9–8.5] to 4.4% [3.0–5.0]; P < 0.02), and pain occurrence and pain interference during sleep (P < 0.01). HWI was well tolerated.

Conclusions

HWI in patients at risk of rapid progression of ADPKD slowed the rate of ht-TKV growth and reduced pain. This suggests that suppressing vasopressin levels by HWI provides an effective nonpharmacologic treatment of ADPKD.

Shockwaves and the Rolling Stones: An Overview of Pediatric Stone Disease

Urinary stone disease is a common problem in adults, with an estimated 10% to 20% lifetime risk of developing a stone and an annual incidence of almost 1%. In contrast, in children, even though the incidence appears to be increasing, urinary tract stones are a rare problem, with an estimated incidence of approximately 5 to 36 per 100,000 children. Consequently, typical complications of rare diseases, such as delayed diagnosis, lack of awareness, and specialist knowledge, as well as difficulties accessing specific treatments also affect children with stone disease. Indeed, because stone disease is such a common problem in adults, frequently, it is adult practitioners who will first be asked to manage affected children. Yet, there are unique aspects to pediatric urolithiasis such that treatment practices common in adults cannot necessarily be transferred to children. Here, we review the epidemiology, etiology, presentation, investigation, and management of pediatric stone disease; we highlight those aspects that separate its management from that in adults and make a case for a specialized, multidisciplinary approach to pediatric stone disease.

Management of autosomal dominant polycystic kidney disease in the era of disease-modifying treatment options

Autosomal dominant polycystic kidney disease (ADPKD) is the reported etiology in 10% of end-stage kidney disease (ESKD) patients and has an estimated prevalence of 12.5 million cases worldwide across all ethnicities. There have been major advancements over the last two decades in understanding the pathogenesis and development of disease-modifying treatment options for ADPKD, culminating in regulatory approval of tolvaptan for ADPKD patients at risk of rapid progression to kidney failure. This review highlights the genetic mutations associated with ADPKD, defines patients at risk of rapid progression to ESKD, and focuses on the management of ADPKD in the era of disease-modifying agents.