THE RELATIONSHIP BETWEEN RENAL CORTICAL VOLUME AND PREDISPOSITION TO HYPERTENSION

It has been proposed that a reduction in the number of nephrons is a r enal abnormality that plays an important role in the pathogenesis of e ssential hypertension. The objective of this study was to determine wh ether renal cortical volume, used as a measure of the number of nephro ns, is lower in normotensive subjects with a familial predisposition t o develop essential hypertension than in subjects who lack this predis position. For this purpose, we measured renal cortical volume using el ectron beam computed tomography in 26 white offspring of two hypertens ive parents (OHT; 14 women, 12 men) and 27 white offspring of two norm otensive parents (ONT; 13 women, 14 men) who were stabilized on a high sodium diet for 3 days (200 mmol/day). In women, mean age was signifi cantly greater in OHT than ONT (46.1 +/- 4.9 [standard deviation] v 41 .8 +/- 5.1 years, respectively, P = .04). In men, means for age and we ight were greater in OHT than ONT (age: 47.1 +/- 7.7 v 37.9 +/- 8.1 ye ars, P < .01; weight: 90.2 +/- 10.7 v 81.1 +/- 9.4 kg, P = .03.) In wo men, mean total cortical volume did not differ significantly between O HT and ONT (156 +/- 33.3 v 166 +/- 30.9 cc, P = .80). After adjustment for interindividual differences in age, mean total cortical volume re mained not significantly different in OHT than ONT (160 +/- 29.0 v 162 +/- 32.4 cc, P = .83), In men, mean total cortical volume was signifi cantly greater in OHT than ONT (210 +/- 33.6 v 180 +/- 20.0 cc, P < .0 1). After adjustment for interindividual differences in age, mean tota l cortical volume remained significantly greater in OHT than ONT (207 +/- 33.2 v 182 +/- 19.8 cc, P = .02). After adjustment for interindivi dual differences in body weight, mean total cortical volume did not di ffer significantly between OHT and ONT (201 +/- 21.7 v 187 +/- 20.1 cc , P = .09). The results of this study do not support the hypothesis th at a decrease in renal cortical volume, as a result of a decrease in n umber of nephrons, is a characteristic of white women or men with a fa milial predisposition to develop essential hypertension.