Many children and adolescents now have high blood pressure that is going undetected, a study has shown.

Doctors described an epidemic of high blood pressure, going hand in hand with the obesity epidemic. They blamed poor diets, salty foods and lack of exercise for the changes.

Professor Bryan Williams, of the University of Leicester, a past president of the British Hypertension Society, said: “We have probably seen a doubling of high blood pressure in the young over the past 20 years.”

He said that lifestyle changes were building up serious health problems that could undermine recent advances in the control of disease.

The US study estimates that as many as one in 20 American teenagers may suffer from high blood pressure. The long-term effects can include heart attack, heart failure, stroke and kidney disease in later life.

Blood pressure is seldom measured in children in the UK, and judging what is a risky level has always been contentious. But a recent study showed that nearly a quarter of young men in Britain have a systolic blood pressure above 140mm of mercury, the cut-off point for adult hypertension.

This finding prompted Professor Francesco Cappuccio, of the University of Warwick, to speak of “an evolving epidemic of hypertension in youth, which is closely associated with a parallel epidemic of obesity”.

This meant, he said yesterday, that by the age of 40 many of today’s teenagers could need multi-drug treatment, as the effects of high blood pressure hit home.

“Twenty years ago 50 was the age of risk for the effects to begin to show,” he said. “Now it’s 25 to 30. We are moving down the age band in seeing the health effects.”

In the new study, published in Journal of the American Medical Association, Matthew Hansen, of Case Western Reserve University, in Cleveland, and colleagues attempted to discover how much undiagnosed high blood pressure there was by looking at the health check records of more than 14,000 children, aged between three and 18, living in northern Ohio.

The results show that of 507 children who had high blood pressure, only 136, just over a quarter, had had such a diagnosis noted on their record. The team concludes that even where blood pressure is measured, doctors are not drawing the appropriate conclusions.

The team said: “Identification of elevated blood pressure in children is important because of the increasing prevalence of paediatric weight problems and because secondary hypertension is more common in children than adults, requiring identification and appropriate work-up.

“If abnormal blood pressure is not identified by a patient’s paediatric clini-cian, it may be years before the abnormal blood pressure is detected, leading to end-organ damage.”

Joe Korner, of the Stroke Association, said high blood pressure in teenagers was unlikely to cause strokes, but it was a very good indicator of the risk of high blood pressure as an adult. “Diagnosing high blood pressure is very important” he said. “It’s not very surprising that it isn’t being diagnosed, but it is of concern.”

He blamed the marketing of junk foods, particularly salty ones, for the changes. Professor Cappuccio agreed: “We have got to stop kids putting on weight, give them a proper diet with lower salt levels, ands stop them starting to smoke” he said. “That should be the message.”

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