FRIDAY, Sept. 21, 2012 (HealthDay News) -- A new study suggests that obese black children have a significantly greater risk for high blood pressure than white children of comparable age and weight.
When white and black children were matched for height and age, black children's blood pressure was 16 percent higher than the blood pressure of white children, said study lead author Dr. Tamara Hannon, an associate professor of pediatrics at Indiana University School of Medicine.
"Black kids really have higher systolic blood pressure at lower BMIs than white children do. It appears that something other than the BMI is contributing to the higher blood pressure," Hannon said. Systolic blood pressure is the upper number in a blood pressure reading.
BMI, or body mass index -- a calculation based on a person's weight and height -- is considered a reliable indicator of whether a person is overweight or obese. Hypertension, a leading cause of stroke, can be associated with higher BMI in children and adults.
Why might obese black children be more susceptible to high blood pressure than whites?
Dr. Ralph Sacco, former president of the American Heart Association and a neurology professor at the University of Miami Miller School of Medicine, said the specific reasons are a little unclear. "While we don't know for sure, one big possibility is sodium consumption. It increases the risk of high blood pressure," Sacco said. "It also could be genetics; salt-sensitive high blood pressure is more frequently seen among African-Americans."
A study recently published in Pediatrics showed that higher sodium intake is associated with a greater risk of high blood pressure among children and teens.
That research also showed that sodium intake seemed to have a greater impact on children who were overweight or obese than it did on kids of normal weight.
Hannon's research group is studying hormone differences in black children that may play a role in their greater risk for high blood pressure. She said other research has shown that blood levels of aldosterone -- a hormone released by the adrenal glands that helps regulate blood pressure -- may differ between white and black kids, even in lean and normal-weight children.
The current study included 821 kids referred to an obesity clinic in Indianapolis. Their average age was 12 and average BMI was 36. A BMI over 30 is considered obese.
Sacco said the study -- scheduled for presentation Friday at a meeting of the American Heart Association in Washington, D.C. -- puts new emphasis on the value of monitoring blood pressure in children. "It's important for pediatricians to focus on blood pressure in children, and critical to focus even more closely on African American kids," he noted.
Hannon agreed. "Even when kids are overweight, health providers of young kids don't often pay attention to blood pressure," she said. "I think really just because you have a minority child with normal BMI, you should still check blood pressure because we know they have an increased risk of hypertension, even if their BMI is normal."
Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
The American Heart Association has more about high blood pressure in children.