Tests for a blood-pressure regulating hormone called renin may help doctors decide which blood pressure drugs their patients should take, researchers said on Wednesday.

They said a mismatch between drugs and patient characteristics may help explain why many people do not benefit from blood pressure drugs, and testing for renin levels may help.

“The one-size-fits-all approach must be abandoned,” said Dr. Curt Furberg of Wake Forest University School of Medicine in North Carolina, who wrote a commentary on the studies in the American Journal of Hypertension.

Currently, fewer than half of patients are helped when they take just one blood pressure drug, and many must take more than one to keep blood pressure down.

A study in May in the Journal of the American Medical Association found that about half of the 65 million people in the United States with high blood pressure have it under control.

Furberg said researchers have known for years that patients respond differently to different drugs for high blood pressure, yet this has not translated into tests and strategies that help find the best treatments for individual patients.

In a series of studies in the same journal, three research teams looked at different aspects of this problem.

Stephen Turner and colleagues of the Mayo Clinic in Rochester, Minnesota, found that blood tests measuring for renin, a hormone produced in the kidney, can help guide doctors in selecting blood pressure drugs.

Patients who had high levels of renin were more likely to respond to the common beta blocker atenolol and less likely to respond to hydrochlorothiazide, a diuretic used to rid the body of unneeded water and salt.

A team led Michael Alderman of Albert Einstein College of Medicine in New York and colleagues found that some people taking blood pressure drugs actually have an increase in their systolic blood pressure - the top blood pressure reading.

This was more common in people with low renin levels who were given a calcium channel blocker or an ACE inhibitor.

And a third study by Ajay Gupta of Imperial College London found that blacks were less likely than whites to respond to anti-renin drugs.

Furberg says the findings suggest the need for new guidelines for treating high blood pressure that incorporate tests to measure a patient’s renin levels.

Morris Brown of Britain’s University of Cambridge said in a commentary that it may be useful to identify patients with extremely high or low renin levels who may not benefit from standard combination of drugs.

Brown said it may be time to consider measuring renin as a part of routine care for high blood pressure.

High blood pressure, or too much force exerted by blood as it moves against vessel walls, is the second-leading cause of death in the United States. About $73 billion is spent per year in the United States treating it.

SOURCE: American Journal of Hypertension, August 2010.