Types of Hypertension
Physicians classify the different kinds of hypertension based on their causes and characteristics. Following are some of the most common types.
About 90%–95% of people with high blood pressure have what’s called essential hypertension or primary hypertension. This means the condition has no identifiable source. Most experts believe essential hypertension is caused by a variety of factors, many of them as yet unknown. If this hypothesis is correct, it may explain why certain treatments lower blood pressure in some people, but not in others. For example, people who are “salt sensitive” can usually control their blood pressure with a low-sodium diet alone, while others find sodium intake has little or no influence on their hypertension.
Isolated systolic hypertension
As people age, their arteries tend to lose elasticity and become less able to accommodate blood surges. The damage created in the vessel lining when blood flows through the arteries at high pressure can be sites of plaque buildup. Eventually, these deposits lead to arteriosclerosis (hardening of the arteries). Arteriosclerosis can elevate systolic blood pressure, while diastolic pressure stays in the normal range. A systolic pressure of 140 or greater coupled with a diastolic reading of 89 or below is called isolated systolic hypertension. This is the most common form of high blood pressure in the elderly.
As its name implies, secondary hypertension arises from some other, often treatable, condition.
Renal artery stenosis
A common cause of secondary hypertension is renal artery stenosis, the narrowing of an artery that supplies the kidney with blood. This condition can occur as a result of a deposit of fatty material on the artery wall (atherosclerotic plaque) or, in young women, from an overgrowth of muscular tissue in the artery wall (fibromuscular dysplasia). Some cases require bypass surgery, but most can be treated successfully by angioplasty.
Another cause of secondary hypertension is overproduction of aldosterone, the hormone made by the adrenal glands that helps the kidneys regulate potassium and sodium levels. This condition, called hyperaldosteronism, causes the body to retain sodium and lose potassium, leading to hypertension, weight gain, muscle weakness, and water retention. If a tumor in the adrenal gland is causing the overproduction, the usual treatment is surgery. In other cases, people with this condition need only to restrict their salt intake and take a medication that blocks the action of aldosterone.
Over secretion of thyroid hormones leading to hyperthyroidism is also a known reason for hypertension and fast heart beat. As happens with most people treated for an overactive thyroid, pulse and blood pressure returned to normal after receiving the treatment to suppress the activity of his thyroid gland.
A rare, usually noncancerous tumor called a pheochromocytoma secretes excessive amounts of epinephrine and norepinephrine, which constrict most arteries and raise blood pressure. Other symptoms may include tremors, palpitations, sweating, nervousness, headache, weight loss, and fainting. Treatment consists of medications that block the hormones’ effects and surgery to remove the tumor. Pheochromocytomas are typically confined to the adrenal glands, which lie on top of the kidneys. However, about 10% spread beyond the adrenals or arise at other sites in the body. If a surgeon cannot remove the tumor, radiation or chemotherapy is necessary.
Cushing’s syndrome is a hormonal disorder characterized by a high level of circulating cortisol, a hormone produced by the adrenal glands. The disorder can cause hypertension, as well as weight gain, swelling of the face, excessive body hair, acne, osteoporosis, diabetes, and a fatty deposit on the upper back called a buffalo hump. Cushing’s syndrome may be caused by excessive stimulation by the adrenal gland or, more commonly, by a person’s taking corticosteroid drugs for extended periods to treat severe allergy or autoimmune disorders. In the first case, treatment generally involves surgery. In the second, attempts are made to reduce the corticosteroid dosage.
Narrowing of the aorta
Coarctation is a rare birth defect in which the aorta, the body’s largest artery, is abnormally narrow. This condition, which may not be discovered until adulthood, causes moderate hypertension in the arms, while blood pressure in the legs is considerably lower. Often, pulses in the groin and legs are very weak or altogether absent. Symptoms include headache, fatigue, and poor circulation in the legs. Surgically repairing the narrowed artery usually alleviates the symptoms of limited blood flow, but hypertension often persists.
Many drugs, including some over-the-counter preparations, can elevate blood pressure. Certain medications prescribed for autoimmune diseases — such as glucocorticoids (also called corticosteroids), cyclosporine, and tacrolimus — constrict blood vessels throughout the body, as do some cancer-treating agents. Hypertension may also be a side effect of nasal decongestants, anabolic steroids, or MAO inhibitors (a class of antidepressants), as well as nonsteroidal anti-inflammatory drugs known as NSAIDs
Shortly after birth control pills came on the market in the ’60s, researchers discovered they raised blood pressure, sometimes to dangerously high levels. As a result, they were found to increase a woman’s risk of having a stroke, particularly among smokers. However, these early oral contraceptives contained considerably higher doses of estrogen and progesterone than current formulations do. Today, it’s much less common for oral contraceptives to cause hypertension, and when it does occur, it’s usually among women who smoke, are obese, or are over 35. In these cases, blood pressure usually returns to normal after the woman stops taking the pill.
The ingestion of lead and cadmium can also cause hypertension.