Treat hypertension, nix kidney failure.
Treating elevated blood pressure can halt -- and even repair - kidney damage kidney damage Kidney injury Nephrology A structural or functional compromise in renal function due to external–eg, athletic, occupational, or other trauma, resulting in bruising or hemorrhage, which can be profuse and life threatening Etiology Vascular caused by the disorder, according to a new analysis of a large study. However, the renal benefits of lowering blood pressure extend only to nonblacks: For as-yet-unknown reasons, blacks with hypertension tend to go on to develop kidney damage whether they receive treatment for the disorder or not, the study found.
The results represent the first time researchers have proved that mild hypertension -- defined as blood pressure between 140/90 millimeters of mercury (mm Hg) and 159/99 mm Hg -- or moderate hypertension -- between 160/100 mm Hg and 179/109 mm Hg -- in fact impairs kidney function. Previous studies only suggested a link between kidney damage and blood pressures in either of these two ranges, which physicians now refer to as stage 1 and stage 2 hypertension, respectively (SN: 11/7/92, p.311).
Kidney dialysis Dialysis, Kidney Definition
Dialysis treatment replaces the function of the kidneys, which normally serve as the body's natural filtration system. centers estimate that the renal failure renal failure
Acute or chronic malfunction of the kidneys resulting from any of a number of causes, including infection, trauma, toxins, hemodynamic abnormalities, and autoimmune disease, and often resulting in systemic symptoms, especially edema, of roughly one-third of all new dialysis patients derives from damage caused by hypertension. Besides serverely curtailing patients' lives, these new dialysis cases add approximately $300 million per year to already spiraling U.S. health care costs, according to the National Institute of Diabetes and Digestive and Kidney Diseases About NIDDK
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), of the U.S. National Institutes of Health, conducts and supports research on many of the most serious diseases affecting public health. in Bethesda, Md.
To confirm the hypertension-kidney damage connection, a research team led by W. Gordon Walker of Johns Hopkins University School of Medicine The Johns Hopkins University School of Medicine, located in Baltimore, Maryland, USA, is a highly regarded medical school and biomedical research institute in the United States. in Baltimore measured concentrations of a waste protein called creatinine in the blood of 5.524 hypertensive hypertensive /hy·per·ten·sive/ (-ten´siv)
1. characterized by increased tension or pressure.
2. an agent that causes hypertension.
3. a person with hypertension. men of all races. Because the kidneys usually filter creatinine -- a by-product by·prod·uct or by-prod·uct
1. Something produced in the making of something else.
2. A secondary result; a side effect.
1. of normal metabolism -- out of the blood and into the urine, blood creatinine measurements can indicate whether a patient's kidneys are working properly.
The men studied by Walker's group were a subset of participants in the Multiple Risk Factor Intervention Trial (MRFIT MRFIT Multiple Risk Factor Intervention Trial Cardiology A long-term prospective study designed to analyze the effects of modifying the risk factors for heart disease ), an even larger study evaluating measures to prevent heart disease among men at risk for the disorder because of cigarette smoking, elevated blood cholesterol, or elevated blood pressure. As part of the MRFIT design, roughly half of the men were given a standardized regimen of drug therapy and put on a modified diet to control their blood pressure. The other half received a variety of different drugs and diet advice from their own physicians.
Walker's group found that the same treatments effectively controlled blood pressure among both blacks and non-blacks, most of whom were white. However, the blood creatinine concentrations of blacks continued to rise, despite reductions in blood pressure, indicating ongoing kidney damage. In contrast, the creatinine concentrations in nonblacks successfully treated for hypertension either stabilized or dropped, signaling that their kidneys were either getting no worse or recovering. The patients were followed an average of seven years.
The researchers conclude that while they cannot explain this racial difference, "the proposition that blacks are more susceptible to renal damage from elevated blood pressure than whites must be considered." But they caution that the number of blacks in their study -- 463, or less than 9 percent of all participants -- may have been too small to draw definitive conclusions.
Walker and his colleagues report their results in the Dec. 2 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION JAMA: The Journal of the American Medical Association is an international peer-reviewed general medical journal, published 48 times per year by the American Medical Association. JAMA is the most widely circulated medical journal in the world. .
"The good news," writes Robert G. Luke of the University of Cincinnati The University of Cincinnati is a coeducational public research university in Cincinnati, Ohio. Ranked as one of America’s top 25 public research universities and in the top 50 of all American research universities, Medical Center in an editorial accompanying the new report, "is that efficient blood pressure treatment ... can probably prevent the annual incidence of endstage renal disease Renal disease
Mentioned in: Glycogen Storage Diseases
hypertension High blood pressure Cardiovascular disease An abnormal ↑ systemic arterial pressure, corresponding to a systolic BP of > 160 mm Hg due to hypertension in patients over 65 years of age from increasing" -- primarily by lowering the incidence of the disorder among whites. However, he warns, "the bad news ... is that progressive renal impairment may not be prevented in African Americans by what is currently accepted as excellent blood pressure control."
"This study is an important advance in our ability to combat the effects of high blood pressure," comments Claude Lenfant, director of the National Heart, Lung, and Blood Institute National Heart, Lung, and Blood Institute,
n.pr established in 1948, this division of the National Institutes of Health is responsible for research and education on cardiovascular, pulmonary, systemic diseases, and sleep disorders. , which administered the 1973-1982 MRFIT study. Following the study's findings, he says, "millions of patients are now known to be at risk for kidney dysfunction if stages 1 and 2 hypertension go untreated."
Lenfant says his institute is planning to launch anotherf study to determine why hypertension treatment that prevents kidney damage among whites doesn't work for blacks. The study -- scheduled to begin next year and to involve several medical centers throughout the United States -- will also examine the causes of hypertension among blacks, he says.