05 December 2008
Twenty-two patients with primary IgA nephropathy (Berger’s disease), 12 with normal and 10 with high blood pressure, were studied. The mean intra-arterial pressure was 88 ± 6 mm Hg in the normotensive group and 113 ± 10mm Hg in hypertensive patients; plasma renin activity was high in normotensives and normal in hypertensives. The glomerular filtration rate was 83 ± 23 and 73 ± 26 ml/m in 1.73m<sup>2</sup> in normotensive and hypertensive patients, respectively (p = n.s.). Blood volume was high in IgA nephropathy patients: 82 ± 12 ml/kg body weight in normotensives and 96 ± 7 ml/kg body weight in hypertensives. Mean arterial pressure was significantly correlated with blood volume (r = 0.541, p < 0.0l), but not with plasma renin activity and glomerular filtration rate. The cardiac index was high in both groups: 4.20 ± 0.88 liters/min/m<sup>2</sup> in normotensive and 3.95 ± 0.87 liters/min/m<sup>2</sup> in hypertensive patients. The total peripheral resistance index was significantly lower than normal in normotensives (1,659 ± 387 dyn/s/ cm<sup>-5</sup>m<sup>2</sup>) and significantly higher (2,419 ± 562 dyn/s/cm<sup>-5</sup>m<sup>2</sup>) in hypertensives. The cardiac index did not correlate with blood volume and mean arterial pressure; a positive correlation was found between mean arterial pressure and peripheral vascular resistance (r = 0.630, p < 0.01). No correlation was observed between blood volume and plasma renin activity. Our study indicates that hypertension in IgA nephropathy is primarily volume dependent, and that this increase in blood volume is not related to the deterioration of renal function. The role of the renin-angiotensin system in the maintenance of the hypertension is not well-defined. Hemodynamically, hypertension is characterized by high cardiac output and high total peripheral resistance.