Aug. 4 (Bloomberg) -- Children in a diagnostic gray zone for high blood pressure should wear 24-hour monitors to help determine if they have the disorder, the American Heart Association recommended.

The continuous monitors offer the best method for doctors to rule out ``white coat hypertension,'' a condition in which healthy children register abnormally high pressure at the doctor's office because of stress, according to a statement published online today in the association's journal, Hypertension. An 11-doctor panel recommended the monitors for children who are just above the limit for normal blood pressure.

An estimated one in four adults worldwide has high blood pressure, also called hypertension, the Dallas-based association said. Catching the disorder early is important because hypertension creates a major risk for heart attacks and strokes in adults, the panel said. High blood pressure can also damage the kidneys.

``The most important take-home message is that clinical hypertension can be identified in children and adolescents and is associated with organ damage even at young ages,'' said Elaine M. Urbina, a cardiologist at Cincinnati Children's Hospital Medical Center who led the panel, in a separate statement.

The heart association previously recommended home monitoring for adults using upper-arm monitors equipped with a cuff. The guidelines for children call for using ambulatory monitors, devices about the size of a portable radio that can be clipped to a patient's belt. The monitors are attached to a cuff that typically checks pressure at least once an hour, day and night, and records the data for physicians to check later.

The Questionable Zone

Cardiac Science Corp., of Bothell, Washington, and Omron Corp., of Kyoto, Japan, make ambulatory monitors. So do A&D Co. of Tokyo and Suntech Medical Ltd., a U.K. company. The devices cost $2,200 to $2,500, according to prices posted on the Internet.

Blood pressure measures the force of the blood against arteries. In children, acceptable levels vary depending on size and gender, the doctors said. In adults, most physicians define hypertension as a systolic blood pressure of 140 and a diastolic pressure of 90, or higher. People with readings between that and 120 over 80 are in a cautionary ``pre-hypertension'' zone.

The statement recommended 24-hour monitoring for children whose office readings are as much as 10 percent higher than the highest acceptable levels. Above that, there's little doubt children have hypertension, the doctors said.

Deciding on Drugs

More study is needed to say just how effective the monitors could be at reducing heart attack and stroke, the panel said. The technology is worth a try, they said, because physicians need a better way of ruling out temporary spikes as well as masked hypertension, in which children with high pressure register normal levels at the doctor's office. Continuous monitoring could also help evaluate the usefulness of blood- pressure drugs, the panel wrote.

``Accurate assessment and management'' of blood pressure ``is essential for the prevention of target organ damage,'' the authors said.

Researchers have found results skewed by white coat hypertension in as many as 88 percent of children studied, the statement said.

The best tool against hypertension for children, doctors said, is getting enough exercise, avoiding obesity and eating foods low in sodium and high in potassium, calcium and magnesium.

To contact the reporter on this story: Alex Nussbaum in New York anussbaum1@bloomberg.net.

Last Updated: August 4, 2008 16:07 EDT