Causes of High Blood Pressure

The causes of hypertension, commonly known as high blood pressure, vary depending on its type. There are two primary categories of hypertension: essential (or primary) hypertension and secondary hypertension. Below, we provide a detailed explanation of the causes associated with each type.

Essential Hypertension

Essential hypertension is the most prevalent form of high blood pressure. This type does not have a specific underlying cause but is influenced by various factors, including lifestyle choices, environmental conditions, and natural changes in blood pressure associated with aging. Typically, essential hypertension develops over several years before it is diagnosed.

Secondary Hypertension

Secondary hypertension occurs when blood pressure rises due to a specific medical condition or as a side effect of certain medications. Typically, managing the underlying cause or discontinuing the medication can lead to improvements in blood pressure. Below are detailed explanations of the causes of secondary hypertension:

Health Conditions

Certain health issues can lead to increased blood pressure. Some of the most notable conditions include:

Glomerular Disease: The glomeruli in the kidneys are responsible for filtering waste and sodium from the blood. When these structures become diseased, it can lead to swelling, impairing their ability to function adequately and resulting in increased blood pressure.
Diabetic Nephropathy: High blood sugar levels can damage the glomeruli, leading to kidney dysfunction and increased blood pressure.
Polycystic Kidney Disease: This genetic condition is characterized by the formation of cysts in the kidneys, which can hinder their function, ultimately raising blood pressure.
Renovascular Hypertension: This type results from the narrowing of arteries supplying blood to the kidneys, often due to atherosclerosis, which can also affect coronary arteries. Additionally, thickening of the muscle and fibrous tissue lining these arteries may contribute to increased pressure.
Adrenal Diseases: The adrenal glands, located above each kidney, secrete hormones that regulate various bodily functions. Disorders in hormone balance can lead to complications such as:
- Pheochromocytoma: A tumor in the adrenal gland causing excessive hormone secretion.
- Primary Aldosteronism (Conn’s Syndrome): This condition involves the overproduction of aldosterone, leading to the retention of salt and water.
- Cushing’s Syndrome: Characterized by increased cortisol production, which can affect blood pressure regulation and carbohydrate metabolism.
Thyroid Disorders: Hyperthyroidism can lead to elevated blood pressure levels.
Hyperparathyroidism: This condition involves the overactivity of the parathyroid glands, leading to increased calcium levels in the blood, which may elevate blood pressure.
Sleep Apnea: This condition, characterized by severe snoring and interruptions in breathing during sleep, impairs oxygen intake, damaging the blood vessel lining and leading to decreased control of blood pressure. Furthermore, it may stimulate an overactive nervous system and increase the release of substances that raise blood pressure.
Aortic Coarctation: This congenital condition involves the narrowing of the main artery in the body (the aorta), resulting in increased pressure as the heart works harder to pump blood through the constricted area.

Medications

Certain medications can also contribute to elevated blood pressure, which usually normalizes upon discontinuation. Examples include:

Steroids
Some oral contraceptives
Non-steroidal anti-inflammatory drugs (NSAIDs), such as naproxen and ibuprofen
Components found in cold and cough medications
Herbal supplements, particularly those containing licorice
Select serotonin-norepinephrine reuptake inhibitors (SNRIs) like venlafaxine
Illicit drugs, such as cocaine
Withdrawal from certain medications like sedatives, alcohol, benzodiazepines, and opioids

Risk Factors for High Blood Pressure

Several factors contribute to an increased risk of developing hypertension. These may be categorized into modifiable and non-modifiable factors:

Non-Modifiable Factors

Age: Blood pressure tends to increase as one ages, meaning older individuals are at a higher risk of developing hypertension.
Genetics and Family History: Genetic predisposition plays a significant role in the likelihood of developing hypertension, particularly in individuals with a family history of the disease. Environmental factors within families may exacerbate these risks, especially when combined with unhealthy lifestyles.
Race: Certain racial groups, such as African Americans, have a higher incidence of hypertension compared to other populations.
Pregnancy: Hypertension can either worsen or first manifest during pregnancy, a condition known as pregnancy-induced hypertension.
Gender: Research indicates that men are generally at a higher risk for hypertension than women until women reach menopause. A 2018 study published in Current Opinion in Nephrology and Hypertension supports this finding.

Modifiable Factors

Several lifestyle choices can increase the likelihood of developing hypertension, but they can be managed effectively to reduce risk. These include:

High Sodium Intake: Elevated sodium levels can lead to fluid retention, causing blood pressure to rise.
Low Potassium Levels: An adequate amount of potassium is essential for sodium balance in the body; thus, poor dietary intake can lead to increased sodium levels and hypertension.
Obesity: Excess weight increases the volume of blood required to supply oxygen and nutrients to the body, which elevates pressure on blood vessel walls.
Alcohol Consumption: Chronic alcohol intake is associated with numerous health issues, including hypertension. Excessive drinking can spike blood pressure to dangerously high levels.
Lack of Physical Activity: A sedentary lifestyle can contribute to a higher likelihood of developing hypertension.
Stress: While stress may not cause chronic hypertension directly, unhealthy coping mechanisms, such as overeating, smoking, or drinking alcohol, can exacerbate the problem.
Smoking: Smoking has an immediate effect of raising blood pressure, and the long-term exposure to tobacco products causes damage to blood vessel walls, increasing the risk of cardiovascular diseases, including hypertension.