The underlying mechanism of this association has been suggested to be related to the expression of ACE2 receptors in kidneys, which results in activating the renin–angiotensin–aldosterone system and increases the absorption of water and sodium in the kidney tubules, causing passive reabsorption of BUN, renal vasoconstriction, and worse prognosis in patients with underlying renal dysfunction.31 This evidence concerns the gene REN and Abnormal renal physiology.