About one in eight
schoolchildren have three or more risk factors of the metabolic
syndrome, a precursor of cardiovascular disease, researchers
reported at the American Heart Association’s Scientific Sessions
risk was about 1.6 times higher for girls than boys,” said the
study’s lead author Joanne S. Harrell, Ph.D., professor of
nursing and director of the Center for Research on Chronic
Illness at the University of North Carolina at Chapel Hill
School of Nursing.
syndrome is a clustering of the cardiovascular disease risk
factors high blood pressure, elevated triglycerides, low levels
of high-density lipoprotein (HDL or “good” cholesterol) glucose
intolerance, elevated insulin levels and excess body weight.
The syndrome puts a person at early risk for diabetes and
coronary heart disease.
regular, normal kids, but we found risk factors that are clear
danger signs for the future. If nothing is done, a good number
of these children could develop type 2 diabetes and heart
disease,” Harrell said.
examined 2,034 students (1,020 girls and 1,014 boys), between
ages 8 and 17. Each lived in rural North Carolina in a county
with no city over 50,000 people. The participants were 48.1
percent white, 42.9 percent African American and 9.1 percent
“We chose to
study children in rural schools with a high minority population
because rural children have slightly higher rates of obesity
than urban children, and type 2 diabetes is more common in
minorities,” Harrell said.
Each child was
evaluated for body mass index, blood pressure, two types of
lipids (fats) in the blood, and two indicators of how well the
body processes glucose. The students will be followed for three
to four years; today’s report is based on the initial testing.
than half of the children (59.3 percent) had at least one of the
six metabolic syndrome risk factors, 28.3 percent had two or
more, and 14.1 percent had three or more risk factors, the
aged 8 and 9 (8.6 percent) already had three or more risk
factors. Among older
14-17, 11.3 percent had three or more risk factors. The highest
rates of multiple risk factors (17.1 percent) were in children
around the onset of puberty, ages 10-13.
The most common
risk factor, found in 41.9 percent of the children, was a low
HDL level. HDL levels were rated low if they were less than 40
milligrams per deciliter (mg/dL) in boys or 50 mg/dL in girls.
The researchers also found high triglycerides in 8.6 percent of
children. Triglycerides were deemed high if they were at least
100 mg/dL in children aged 10 or younger or 130 mg/dL in
children older than 10.
More than one in
four of the participants were classified as overweight, with a
body mass index at or above the 95th percentile for
someone of their age, gender and height.
researchers had documented a very high prevalence of obesity,
one factor in the metabolic syndrome, in teenagers. This study
looks at the development and clustering of six metabolic
syndrome risk factors beginning prior to puberty and continuing
through the teen years.
resistance is normal with puberty. In addition, obesity
increases with puberty, earlier in girls than boys,” Harrell
said. “As we follow the children, we’ll see whether these
metabolic syndrome factors persist in adolescence.”
more girls (17.2 percent) than boys (11 percent) had three or
more metabolic syndrome risk factors, which the researchers
attribute to higher levels of overweight in the girls.
High levels of
insulin in the blood (more than 25 microunits per liter) were
found in 16 percent of the children. High blood pressure was
detected in 10.8 percent. Children were considered to have high
blood pressure if their average systolic or diastolic pressure
was at or above the 95th percentile (for their
gender, age and height) on three separate occasions.
prevalent (5 percent) risk factor was glucose intolerance, or
prediabetes, marked by a fasting glucose level of at least 110
“The body tries
very hard to keep glucose normal. Typically you would have the
metabolic syndrome for several years before glucose tolerance
becomes impaired,” Harrell said.
on these children may eventually help physicians determine who
needs to be screened for various metabolic syndrome risk
factors, and at what age. Meanwhile, data already reinforces
the need for primary prevention of heart disease in youth,
“I want to alert
people to the potential dangers and motivate people to help our
youth increase physical activity and avoid obesity,” she said.
activity can help improve most metabolic syndrome factors,
including HDL levels, obesity, high blood pressure and insulin
resistance, she said. Preventing obesity also helps avoid other
metabolic syndrome risk factors.
Robert G. McMurray, Ph.D.; Leila Amorim, M.S.; Dana Creighton,
M.A. and Shrikant I. Bangdiwala, Ph.D.