Sodium Sensitivity of Blood Pressure Appearing Before Hypertension and Related to Histological Damage in Immunoglobulin A Nephropathy

Abstract

Abstract-Patients with renal parenchymal disease exhibit sodium-sensitive hypertension. We examined patients with immunoglobulin A (IgA) nephropathy to determine whether this sensitivity appears before hypertension begins and whether this sensitivity is related to histological damage. Thirty-eight patients with IgA nephropathy followed a diet with an ordinary sodium level for 1 week and a sodium-restricted diet for 1 week, in random order, and were divided into 3 groups by their systemic blood pressure on the diet with an ordinary sodium level (optimal, Ͻ120/Ͻ80 mm Hg, nϭ15; normal to high-normal, 120 to 139/80 to 89 mm Hg, nϭ18; hypertensive, Ն140/Ն90 mm Hg, nϭ5). The sodium sensitivity index was calculated as the reciprocal of the slope of the pressure-natriuresis curve drawn by linkage of 2 datum points obtained during the different diets. The scores for glomerulosclerosis and tubulointerstitial damage were evaluated semiquantitatively. The sensitivity index, glomerulosclerosis score, and score for tubulointerstitial damage were higher in patients with normal to high-normal blood pressure or hypertension than in patients with optimal pressure. The sensitivity index was significantly correlated with glomerulosclerosis (Pϭ0.001) and tubulointerstitial damage (Pϭ0.002). In patients with normal to high-normal pressure, sodium restriction lowered blood pressure to the optimal range and decreased proteinuria. In patients with IgA nephropathy, sodium sensitivity of blood pressure related to renal histological damage appears before hypertension.

Salt sensitivity and circadian rhythm of blood pressure: the keys to connect CKD with cardiovasucular events

“…We recently showed this quantitative relationship in CKD 38,39 and healthy donors after nephrectomy, 40 in both of whom there was an inverse relationship between GFR and the night/day ratio of BP. These findings are compatible with high salt sensitivity of BP in glomerulopathy, even when GFR is maintained at a relatively normal level, 41,42 ultimately becoming much higher as renal function deteriorates. 43,44 These findings are also compatible with the proposal that as the number of nephrons is reduced BP becomes more salt sensitive.…”

Benidipine Attenuates Glomerular Hypertension and Reduces Albuminuria in Patients with Metabolic Syndrome

“…We also found that the estimated glomerular capillary pressure (PGC) was elevated in patients with sodium-sensitive essential hypertension and primary aldosteronism (7), a typical form of sodium-sensitive hypertension due to secondary causes. In addition, it has been well established that BP becomes sodium sensitive in patients with chronic glomerulonephritis (8), and sodium sensitivity has also been reported to be greater as the GFR declines (9). These findings strongly support the interrelationships among salt sensitivity, glomerular hypertension, renal damage, and microalbuminuria.…”

Blunted Response of the Renin-Angiotensin System and Nitric Oxide Synthesis Related to Sodium Sensitivity in Immunoglobulin A Nephropathy

“…Our recent study of patients with IgA nephropathy showed that the sodium sensitivity of blood pressure is significantly correlated with glomerulosclerosis (8). The more the number of glomeruli is decreased, the more blood pressure becomes sodium-sensitive.…”

“…Thirty-nine Japanese inpatients with IgA nephropathy participated in this study; the 11 men and 28 women were aged 20 to 59 years. Thirtythree of these patients were described earlier (8). The patients' characteristics are shown in Table 1.…”