Hypertension, heart disease and diuretics.

Hypertension, heart disease and diuretics 

An estimated 7 million people in the united States may have inherited a syndrome of hypertension and elevated blood lipids that puts them at high risk of aheart attack, according to study results reported last summer. And Swedish research suggests that a class of drugs commonly used to treat hypertension may also heighten the threat of heart disease.

Roger R. Williams, Steven C. Hunt and their colleagues at the University of Utah in Salt Lake City first described the syndrome, called familial dyslipidemic hypertension, in the June 24, 1988 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION. In that report they detailed a study of 131 hypertensive siblings from 58 families and concluded that a pattern of hypertension and abnormal blood lipid levels seems to run in families.

Scientists know that people with hypertension have alterations in the transport system that carries sodium and other ions across cell membranes. But new work by the Utah team shows that people with this syndrome have more ion-transport abnormalities than do hypertensives with normal blood lipid levels. The researchers described their latest findings Sept. 28 in Cleveland at the 43rd Annual Fall Conference and Scientific Sessions of the American Heart Association Council for High Blood Pressure Research.

Williams and Hunt found that people with the greatest ion-transport problems had high blood levels of insulin, a hormone produced by the pancreas. High blood insulin values suggest that people with this syndrome may have a disorder called insulin resistance, in which the body doesn't respond properly to insulin (SN: 9/16/89, p. 184). Some researchers believe insulin resistance is at the core of a lethal process leading to heart disease. Hunt says his team doesn't know whether insulin resistance or some other factor underlies familial dyslipidemic hypertension.

Most people with the syndrome get treatment for their high blood pressure, but physicians often ignore their high blood lipids, the researchers find. "When physicians see high blood pressure develop early in a patient, they should check the lipid levels and blood pressure of that patient's brothers and sisters," Williams says. If scientists can find a genetic marker for the disorder, it might enable physicians to identify affected children and start treatment before cardiovascular damage occurs, the researchers say.

Most scientists agree that people with hypertension and lipid disorders can lower their heart disease risk by losing weight, exercising and cutting down their consumption of saturated fats. Scientists disagree, however, on when such patients need to start taking medication to lower their high blood pressure.

Hunt notes that many people with the newly identified syndrome take diuretics, which treat hypertension by reducing water in the body. But a new report by a team of Swedish researchers suggests diuretics may boost the risk of heart disease for all people with hypertension.

Thomas Pollare and his colleagues at Uppsala University studied 50 patients with hypertension, finding that when subjects took the diuretic drug hydrochlorothiazide they had significantly higher blood levels of cholesterol than did subjects receiving placebo pills. When the researchers gave these same patients captopril, one of a class of drugs known as ACE inhibitors that reduce blood pressure by reducing blood vessel constriction, their blood lipid levels were no higher than those of patients on the placebo.

The team reports in the Sept. 28 NEW ENGLAND JOURNAL OF MEDICINE that hydrochlorothiazide made body tissues less responsive to insulin. Some scientists say such evidence argues against diuretic treatment for certain people with hypertension, especially those with insulin resistance.