REN and Hypercholesterolemia: Borghi et al. investigated possible interactions between serum cholesterol levels and the renin–angiotensin system on the development of stable hypertension in 66 young (age < 45 years) patients with high-normal blood pressure, and demonstrated that the presence of hypercholesterolemia could promote the development of stable hypertension through its interaction with the circulating renin–angiotensin system [25].