What Causes High Blood Pressure? In many people with high blood pressure, a single specific cause is not known. This is called essential or primary high blood pressure. While no single factor is known, scientists believe the following factors play a large role in causing high blood pressure:
Causes of Primary Hypertension
- High Salt Intake: Primary hypertension generally only occurs in people that have an excess level of salt intake (generally > 5.8 g / day) and thus is thought to be one of the most important factors that can contribute to high blood pressure.
- Genetic factors are thought to play a heavy role in the development of primary hypertension. Scientists believe that approximately 30% of high blood pressure cases are due, at least in part, to genetic factors. Individuals who have one or two parents with hypertension are twice as likely to develop hypertension than the rest of the population. Scientist have also observed that certain minority groups, such as African Americans, have a much higher incidence of hypertension than Caucasian and Asian American groups.
- Other factors: obesity, excessive alcohol consumption, sedentary lifestyle, low potassium diets
Secondary hypertension, by definition, is caused by a specific identifiable disorder of a particular organ or of the blood vessels. The main causes of secondary high blood pressure are:
- Renal Hypertension (kidney) or Renovascular Hypertension is caused by narrowing of the arteries that carry blood to the kidneys. During renovascular hypertension, one or both of the kidney arteries become narrow. This reduces blood flow to the kidneys, and the affected kidney or kidneys mistakenly respond as if the patient's blood pressure is low. They secrete hormones that tell the body to retain salt and water. This causes an increase in blood pressure. Many different diseases can cause narrowing of the renal arteries.
- Renal artery stenosis is one of the most common. Renal artery stenosis is a narrowing or blockage of the artery that supplies the kidney, caused by atherosclerosis, fibromuscular dysplasia of the renal artery wall, or scar formation in the artery. Renal artery stenosis is, in fact, among the most common causes of secondary hypertension. The disorder may also be discovered when a bruit (loud whooshing sound) over the kidney is noted on examination with a stethoscope (auscultation). Other casues of renal hypertension include inflammatory kidney diseases, as well as damage due to drugs or diabetes.
- Adrenal gland tumors, though less common, can cause secondary hypertension. In Primary hyperaldosteronism, the tumor produces excess amounts of the hormone aldosterone, which in turn directly affects blood pressure. Another type of tumor that causes hypertension is pheochromocytoma. In pheochromocytoma, the tumor produces catecholamines, which include several adrenalin-related hormones.
- Thyroid Dysfunctions, such as an overactive or underactive thyroid an lead to hypertension.
- Coarctation of the aorta is an extremely rare hereditary disorder. Coarctation of the aorta is a narrowing of the aorta between the upper-body artery branches and the branches to the lower body. This blockage can increase blood pressure in your arms and head, reduce pressure in your legs and seriously strain your heart.
- Sleep Apnea, also known as Obstructive Sleep Apnea, is known to raise blood pressure. Obstructive sleep apnea is a stroke and cardiac risk factor and needs to be treated by a sleep disorder specialst.
- Mediation & recreational drugs, including over-the-counter medications as well as illicit drugs can elevate blood pressure. Usually, the hypertension caused by the drugs subsides once the person stops taking the drug.
- Pregnancy related conditions such as preeclampsia and eclampsia can raise blood pressure.
Resistant hypertension is the failure to reach goal blood pressure in patients who are adhering to full doses of an appropriate three-drug regimen that includes a diuretic. After excluding potential identifiable causes of resistant hypertension, clinicians should carefully explore reasons why the patient is not at goal blood pressure. Particular attention should be paid to diuretic type and dose in relation to renal function. Consultation with a hypertension specialist should be considered if goal blood pressure in resistant hypertensive patients cannot be achieved.