Abstract

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of kidney failure in the world. Currently there are no treatments to prevent kidney due to ADPKD. Vitamin D is traditionally known for its role in maintaining calcium balance and normal bone health, but it is being increasingly being recognised for a number of other important physiological functions, including reducing blood pressure and proteinuria as well as kidney inflammation andfibrosis. Vitamin D deficiency is associated with proteinuria, increased mortality and may mediate the progression to kidney failure. Recent data from an Australian cohort study (AusDiab) reveals that vitamin D deficiency and insufficiency are common conditions, affecting 26.6% and 42.1% of the Australian community respectively. Preclinical studies from our laboratory have identified that vitamin D deficiency exacerbates proteinuria and hypertension in experimental PKD, and that this is reversed by treatment with vitamin D receptor agonist. In this manuscript, we report the rational and design of an open-label observational study of humans with ADPKD (eGFR>30 ml/min/1.73m2). All subjects will undergo screening for vitamin D levels at the beginning of study, and those that are found to be either deficient (<50 nmol/L) or insufficient (<75 nmol/L) will be repleted with oral cholecalciferol for 6 months. We predict that cholecalciferol will attenuate hypertension, proteinuria and reduce the urinary excretion of a biomarker, monocyte chemoattractant protein-1 (MCP-1, a surrogate inflammatory marker of progression in ADPKD). This study will provide evidence as to whether a simple intervention such as vitamin D repletion, in either deficient or insufficient states, is a treatment to prevent kidney failure in ADPKD.

Keywords: Vitamin D, polycystic kidney disease, progression.