Defined as blood pressure higher than 140/90, hypertension affects over 74 million Americans, or one in three adults, the American Heart Association reports. Nearly 25 percent don’t know they have high blood pressure, which is easily diagnosed and usually controllable, they add. Blood pressure readings measure the amount of pressure in blood vessels when they contract, called the systolic reading and when they’re relaxed, called the diastolic reading, and is reported as systolic over diastolic, with 120/80 considered normal, says Medline Plus. Hypertension, or high blood pressure, can have many causes.
Essential, or Primary Hypertension
Hypertension can be primary, also known as essential, or secondary, meaning it results from another disease. Essential hypertension, which comprises the majority of cases of hypertension, has no identifiable cause, the University of Maryland Medical Center states. While the cause of essential hypertension isn’t known, certain risk factors increase the odds of developing it. African Americans, Caucasian males and older people are prone to developing essential hypertension, which normally has few if any symptoms. Essential hypertension can damage blood vessels over time and increase the risk of heart disease, kidney or eye damage, or stroke. Medications and lifestyle changes such as decreasing sodium intake, increasing exercise and losing weight all aid in reducing essential hypertension.
Pregnancy Induced Hypertension
Pregnancy induced hypertension, often shortened to PIH, occurs in around 7 to 10 percent of pregnancies, says the Children’s Hospital of Wisconsin. PIH differs from chronic hypertension, because it exists only during the time of pregnancy. Symptoms of PIH include protein in the urine, increased blood pressure and edema, or swelling. The exact cause of PIH currently remains unknown, although it may occur in women with existing hypertension, kidney disease or diabetes and is more common in women carrying multiples, women in their first pregnancy and mothers under age 20 or over age 40.
PIH reduces blood flow through the placenta to the fetus, sometimes resulting in growth retardation and preterm delivery, Children’s Hospital of Wisconsin explains.
The placenta can prematurely separate from the uterine wall, causing severe blood loss and possible death of mother and infant. Life-threatening maternal seizures, called eclampsia, can also occur in mothers with PIH. PIH treatments include bed rest, anti-hypertensive medications and delivery.
Secondary hypertension has many causes. The most common include kidney disease related to diabetes or other causes, adrenal gland tumors, low thyroid levels, obesity, sleep apnea and coarctation of the aorta, a congenital defect of the main blood vessel that leads from the heart. Medications such as immunosuppressants given after organ transplant, corticosteroids, antidepressants and birth control pills, as well as illegal drugs such as cocaine, also cause secondary hypertension, MayoClinic.com explains.
About this Author
Suzanne Robin started writing professionally for the Wiley “Dummies” series in 2001. She has co-authored seven books for the series and acted as developmental editor for several more. She has also worked as a registered nurse in oncology, labor/delivery, neonatal intensive care, infertility and ophthalmology. Robin received her registered nursing degree from Western Oklahoma State College.