REN and Stroke: Biological plausibility for such an association exists, as vitamin D has known renoprotective properties through multiple mechanisms, including regulation of the renin-angiotensin-aldosterone system, anti-inflammatory effects, maintenance of endothelial function, and mitigation of oxidative stress (24–29), all of which may be particularly relevant in the post-stroke setting where hemodynamic instability and systemic inflammation can compromise renal function (30, 31).