2.1
Hypertension is usually asymptomatic, but it is a common and preventable cause of premature morbidity and death. It is a major, but modifiable, risk factor for cardiovascular disease (including stroke and myocardial infarction) and chronic kidney disease. The cause of primary hypertension, which is the most common form, is not fully understood. However, it is likely to involve multiple factors including an increase in sodium retention and a reduction in renal blood flow mediated by the sympathetic nervous system. Secondary hypertension, which is less common, is caused by conditions affecting the kidneys, arteries, heart or endocrine system.