High blood pressure, also known as hypertension, is dangerous because it can contribute to strokes, heart attacks, heart failure, kidney damage, vision loss, damage to arteries, certain types of dementia and a metabolic syndrome of high fat and cholesterol in the blood. It is important for health care practitioners to find the cause so they may effectively manage the hypertension and prevent complications.
Primary
Primary, or essential, hypertension has no known cause. Certain factors in the environment increase the risk for hypertension, but the step-by-step mechanisms leading from those risk factors to the development of hypertension are incomplete. These risk factors include a family history of high blood pressure, race, older age, obesity, sedentary lifestyle, excess salt in the diet, tobacco use, low vitamin D, excessive alcohol consumption and stress.
Renal Artery Stenosis
The kidneys have several functions in the body, primarily to filter the blood. Another function is to modulate the blood pressure. In renal artery stenosis, the artery leading to the kidney narrows, usually either from growth of the muscular layer in the blood vessel, called fibromuscular dysplasia, or the deposition of plaque within the vessel, called atherosclerosis. The kidneys receive less blood and respond as if the blood pressure is low. It releases hormones that initiate a process of increasing the blood pressure. In the case of atherosclerosis, cholesterol-lowering drugs may be attempted along with blood pressure drugs. Both types may be treated by threading a catheter into the blood vessel and stenting it open with mesh.
Pheochromocytoma
Pheochromocytomas are a type of tumor, or overgrowth of cells. In this case, they are the overgrowth of cells that produce hormones such as epinephrine, commonly known as adrenaline, and norepinephrine, responsible for the fight or flight response, including increasing the blood pressure. Medications are given to lower blood pressure, followed by surgical removal of the tumor.
Excessive Adrenal Hormones and Other Hormonal Disorders
Several adrenal hormones and hormones of other glands are responsible for increasing the blood pressure. The adrenal glands sit on top of the kidneys. The outer layer of the adrenal glands release cortisol, a stress hormone, and aldosterone, a hormone for salt retention and increasing the blood pressure. Disorders that increase the output of these hormones, such as tumors of the cells that produce the hormones, or congenital adrenal hyperplasia, an inborn deficiency of certain enzymes, both increase blood pressure. Thyroid and parathyroid problems also increase blood pressure.
Sleep Apnea
Sleep apnea is a condition whereby people stop breathing in their sleep. It is caused by either blockage of the flow of air in the throat called obstructive sleep apnea, or less commonly, dysregulation of breathing in the brain. Daytime and nighttime blood pressure levels decrease significantly after treatment for obstructive sleep apnea, according to a study published in American Family Physician.
Coarctation of the Aorta
Anatomical problems can also lead to hypertension. In coarctation of the aorta, the main blood vessel coming off of the heart to supply the body with blood has an abnormally small diameter. The blood pressure in the arms may be significantly different from the pressure in the legs. Treatment is usually surgical.
References
- Mayo Clinic: High Blood Pressure
- National Institutes of Health: Renal Artery Stenosis
- Medline Plus: Pheochromocytoma
- "Harrison's Principles of Internal Medicine"; Anthony Fauci et al; 17th Ed. 2008
- American Family Physician: Treating Obstructive Sleep Apnea Improves Essential Hypertension and Quality of Life
