Causes of Primary Hypertension

When high blood pressure (hypertension) has no underlying medical cause, such as kidney or thyroid disease, it is called primary hypertension. Most people with hypertension have this category of the condition. In primary hypertension, the exact cause is not known; however, there are some identifiable factors that may play a role in the development of high blood pressure.

Sodium (Salt) in the Diet

• The amount of salt in one's diet can cause blood pressure to rise. Too much salt can cause fluid retention and increase the amount of blood in the blood vessels, which increases blood pressure. Also, salt causes the muscles in blood vessels to constrict (tighten), which makes the blood vessels smaller and raises blood pressure. Lowering the amount of salt in the diet can have an impact on blood pressure levels; however, this change cannot be recommended as a method of treatment by itself.

Insulin Resistance

• When the body does not respond to insulin, a hormone that regulates the level of blood glucose, the pancreas produces more of it. Elevated insulin levels can increase the activity of the sympathetic nervous system as well as cause the kidneys to retain salt (sodium). Both of these activities can cause the blood pressure to elevate. Obesity also can play a role in insulin resistance, and weight loss can improve the condition.

Obesity

• Obesity is associated with a high risk of developing high blood pressure. Those people with a body mass index over 25 are at extremely high risk of developing hypertension. Obesity also can cause insulin resistance by causing the body to not respond to insulin, which leads to increased blood pressure. The combination of insulin resistance, obesity and hypertension, along with elevated cholesterol levels and elevated clotting factors, is called metabolic syndrome.

Genetics

• If other members of a person's family have hypertension, he is at higher risk of developing high blood pressure. There is a genetic component in the development of hypertension; researchers have found up to 50 specific genes that can cause high blood pressure. Genetics may also influence how other potential harmful lifestyle choices influence the body and may cause high blood pressure.

Exercise

• Lack of exercise can lead to hypertension as well. People who are not physically active are at higher risk of being overweight, which increases the risk of hypertension. However, a recent study by Franceschini and colleagues showed that smoking, alcohol intake and the lack of exercise can interact with one's genetics to impact and increase the risk of developing high blood pressure. This supports the belief that many behaviors and factors may work together to increase the risk of hypertension, and more study needs to be done to identify particular genes and what each reacts with.

Race, Sex and Age

• African Americans are twice as likely as white Americans to develop hypertension. Men are more likely to be affected than women, and the risk of hypertension goes up with increasing age. Other factors, such as obesity, diabetes, exercise or genetics, may interact with race, sex or age to cause this increased risk; more research is needed to further explain the multifactorial nature of hypertension.

Considerations

• Since there are identifiable risk factors in the development of primary hypertension, people with these risk factors should consider modifying lifestyle behaviors that increase the risk of high blood pressure. While genetics, sex or race cannot be altered, taking all of these factors into account can help improve one's health and lower the risk of hypertension.