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One consequence of hypertension (high blood pressure) can be kidney damage, and identification of kidney disease (nephropathy) in its earliest stages is highly desirable. The glomerular filtration rate, the rate at which fluid is filtered by the glomeruli (small structures in the kidney through which fluid passes on its way to becoming urine), may be such an indicator. Increases in the rate (hyperfiltration) are known to precede the development of some kidney diseases. To evaluate whether glomerular filtration rate could be a good predictor of nephropathy, 111 patients with mild to moderate hypertension (diastolic blood pressure consistently higher than 90 mm Hg after resting) were studied. Patients underwent echocardiography (ultrasound examination of the heart) to measure the chambers of their hearts; certain findings are known to be correlated with the risk of vascular disease in hypertensive patients. In 52 patients, invasive studies were performed to evaluate kidney function. Results showed a significant correlation between glomerular filtration rate and the mass and cross-sectional area of the left ventricle (the chamber of the heart that pumps blood to the body). Patients with left ventricular hypertrophy (enlargement) had higher glomerular filtration rates than patients who did not have ventricular hypertrophy. The patients had normal kidney function. Whether glomerular hyperfiltration is an early stage of nephropathy remains to be determined; however, it appears to be related to at least one other variable (left ventricular hypertrophy) that is associated with structural change in hypertensive patients. (Consumer Summary produced by Reliance Medical Information, Inc.)

Although people with high blood pressure (hypertension) are at increased risk for cardiovascular disease, many do not develop it. Within a group of individuals with similarly elevated blood pressure, some are at higher risk for cardiovascular disease than others; identification of these persons has not proved easy. One measurement known to be correlated with increased risk is left ventricular (LV) hypertrophy (enlargement of the left ventricle, the chamber of the heart that pumps blood to the body). LV mass can be measured noninvasively with echocardiography, which uses ultrasound. The relationship between LV mass and cardiovascular disease is so consistent that other physiological abnormalities found to be correlated with LV mass are investigated for their predictive values. Such is the case with the glomerular filtration rate (the rate at which the kidneys filter the blood), as shown in an article in the December 5, 1990 issue of The Journal of the American Medical Association. The investigators found that patients with increased glomerular filtration rates also had increased LV mass. It was proposed that glomerular hyperfiltration is a sign of early vascular disease from hypertension. The limitations of LV mass measurement as an indicator of damage due to hypertension are discussed. Although it is clearly helpful in deciding whether patients with borderline hypertension require medication, an effect of antihypertensive treatment on LV mass has not been reliably demonstrated. Repeated measurements on patients under treatment, therefore, do not yield useful information about treatment effectiveness. Finally, hypertension is increasingly being viewed as a cardiovascular disease in and of itself. (Consumer Summary produced by Reliance Medical Information, Inc.)