decreases the liver’s production of VLDL and low-
density lipoprotein (LDL), which curtails triglyc-
eride production. Niacin can cause unpleasant
facial flushing and tingling sensations in the fin-
gers and toes, however, even at low doses.
Risk Factors and Preventive Measures
The key risk factors for hyperlipidemia are family
history and lifestyle habits. Most people can lower
their risk for hyperlipidemia through eating habits
and exercise. Even in combination with medica-
tion, lifestyle factors are important for maintaining
healthy lipid metabolism.
See also CARDIOVASCULAR DISEASE PREVENTION;
CHOLESTEROL BLOOD LEVELS; CHOLESTEROL, ENDOGE-
NOUS; C-REACTIVE PROTEIN; TRIGLYCERIDES, BLOOD
LEVEL; XANTHOMA.
hypertension BLOOD PRESSUREthat remains consis-
tently elevated. Health experts estimate that 25
percent of American adults—about 75 million peo-
ple—have hypertension, though about half of them
do not know it. Hypertension, also called high
blood pressure, is a leading cause of STROKEand KID-
NEYdisease, and a key factor in many heart attacks.
Stroke kills nearly 150,000 Americans each
year, making it the third leading cause of death in
the United States, and disables about a million
others. Yet as many as 80 percent of strokes are
preventable through controlling blood pressure.
Early diagnosis of hypertension to prevent stroke
is a goal of the U.S. preventive health initiative
HEALTHYPEOPLE2010.
Loss of feeling or movement and
blurred or dimmed vision, especially on
only one side of the body, and difficulty
forming or understanding words, are
early warning signs of STROKE that
require emergency medical evaluation.Hypertension has numerous effects on the car-
diovascular system, and over time alters the func-
tion of the HEART as well as the distribution of
blood throughout the body. Hypertension in com-
bination with ATHEROSCLEROSIS, the most common
form of CARDIOVASCULAR DISEASE(CVD) in the United
States, can be particularly damaging or lethal. In
combination with DIABETES, hypertension signifi-
cantly raises the risk for kidney failure and
RETINOPATHYof diabetes, in which the tiny blood
vessels in the RETINArupture, causing blindness.Symptoms and Diagnostic Path
Hypertension has no symptoms, which is why reg-
ular blood pressure monitoring is so important.
For many people, the first indication of hyperten-
sion is stroke or kidney disease, the two leading
complications of hypertension. Hypertension may
also trigger HEART ATTACK. Occasionally people who
have severely elevated blood pressure experience
headaches.
Healthy blood pressure is a systolic reading
below 120 millimeters of mercury (mm Hg) and a
diastolic reading below 80 mm Hg. Persistent read-
ings above these levels for either systolic or diastolic
pressure constitute hypertension. Generally the
doctor takes several blood pressure readings at dif-
ferent times of the day over a span of time before
diagnosing hypertension. A diagnosis of hyperten-
sion follows a minimum of three elevated readings.
Many people are anxious or nervous when visiting
the doctor, sometimes resulting in a phenomenon
doctors call “white coat hypertension.” An assess-
ment of vital signs, including blood pressure, usu-
ally takes place at the start of the health-care visit;
when blood pressure is elevated, the doctor may
take a measurement again at the end of the visit
when the person’s anxiety level has dropped.HYPERTENSION CLASSIFICATIONS
Classification Systolic Diastolic
Prehypertension 120–139 mm Hg 80–89 mm Hg
Stage 1 hypertension 140–159 mm Hg 90–99 mm Hg
Stage 2 hypertension 160 mm Hg and above 100 mm Hg
and aboveTreatment Options and Outlook
Lifestyle modification is the first and the founda-
tional treatment approach for hypertension. Inter-
vention at the prehypertension level can bring
blood pressure under control before it becomes a
health problem. Overweight or OBESITYcauses or
exacerbates much hypertension, so often the doc-
tor’s first recommendation is weight loss through
increased physical activity and changes in eating
habits that reduce overall caloric intake. Further
dietary modifications often include reducing66 The Cardiovascular System