AVP and autosomal dominant polycystic kidney disease: In this study ADPKD patients with later stages of disease showed markedly higher AVP and copeptin levels at the end of a water deprivation test compared to levels that were achieved in our previous study that was performed in ADPKD patients with earlier stages of disease (9.2 (1.4–12.0) pmol/L vs. 1.6 (1.13–2.41) pmol/L, p = 0.007) [4].