In 90-95 percent of high blood pressure cases, the cause is unknown. Fortunately, even though scientists don't fully understand the causes of high blood pressure, they've developed both non-drug and drug treatments that are effective over the long term in treating this disease. In the remaining cases, high blood pressure is a symptom of a recognizable problem such as a kidney abnormality, tumor of the adrenal gland or congenital defect of the aorta. When the root cause is corrected, blood pressure usually returns to normal. This type of high blood pressure is called secondary hypertension.
High levels are a large factor in clogging arteries.
Your blood pressure is also checked each time you donate. Cholesterol levels are also checked periodically.