The primary objective of the trial is to evaluate whether six weeks treatment with tablet tolvaptan is more efficient than no tolvaptan treatment on the reduction of total kidney volume (tKV) in patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD).

The secondary objectives of the trial are to evaluate the effect of six weeks treatment with tablet tolvaptan versus no tolvaptan treatment on CrEDTA measured glomerular filtration rate (GFR) and safety.

The study is an investigator- initiated controlled multi-centre trial in a Prospective, Randomised, Open, Blinded Endpoint, (PROBE) design.

Multicenter study: 10-12 patients are included at Aarhus University Hospital.

MR scans at baseline and after 6 and 12 weeks. Renal and cyst volumes are measured using MRI.

Lisbet Brandi, MD, DMSc, MHM. Department of Cardiology, Nephrology and Endocrinology, Nordsjællands Hospital, Hillerød, Denmark.

Anne Dorte Blankholm PhD, MSc, Radiographer, Department of Radiology, Aarhus University Hospital, Denmark.