Hypertension is defined as a systolic blood pressure greater than 140 mmHg or a diastolic pressure greater than 90 mmHg based on multiple measurements over multiple visits. Hypertension can result from increased cardiac output, increased peripheral resistance, or both. The causes of hypertension include increased sympathetic nervous system activity, increased renal sodium reabsorption, increased activity of the renin-angiotensin-aldosterone system, decreased vasodilation, and resistance to insulin action. Risk factors include family history and lifestyle factors such as physical inactivity, obesity, and smoking.