Microalbuminuria in salt-sensitive patients. A marker for renal and cardiovascular risk factors.

Abstract

We previously showed that a high salt diet increases glomerular capillary pressure in salt-sensitive hypertensive patients and suggested that this may underlie the greater propensity of these patients to develop renal failure. Because microalbuminuria is considered an initial sign of renal damage, we have tested whether salt-sensitive patients display greater urinary albumin excretion than salt-resistant hypertensive patients. Twenty-two patients were placed on a low sodium intake (20 mEq/d) for 7 days followed by a high sodium diet (250 mEq/d) for 7 more days. Twelve patients were classified as salt sensitive and 10 as salt resistant. Urinary albumin excretion was greater in salt-sensitive than saltresistant patients (54±11 versus 22±5 mg/24 h, P<.01). During the low sodium diet, glomerular filtration rate, renal plasma flow, and filtration fraction were similar between the two groups. During the high sodium intake, glomerular filtration, renal plasma flow, filtration fraction, and calculated intraglomerular pressure did not change in salt-resistant patients; in salt-sensitive patients, however, renal plasma flow decreased, and filtration fraction and intraglomerular pressure increased, whereas glomerular filtration rate did not change. Urinary albumin excretion was significantly correlated with glomerular capillary pressure. Salt-sensitive patients displayed higher serum levels of low-density lipoprotein cholesterol and lipoprotein(a) and lower levels of high-density lipoprotein cholesterol than salt-resistant patients. These studies have shown greater urinary albumin excretion and serum concentrations of atherogenic lipoproteins in salt-sensitive than in salt-resistant hypertensive patients, suggesting that salt sensitivity may be a marker for greater risk of renal and cardiovascular complications. (Hypertension. 1994;23:195-199.)

Silent ischemia is more prevalent among hypertensive patients with microalbuminuria and salt sensitivity

“…These studies have also confirmed that saltsensitive hypertensive individuals manifest greater urine albumin excretion rate than salt-resistant patients. 18 Moreover, while office blood pressure was not different among these two groups, daytime and nighttime ambulatory blood pressure levels were significantly greater among salt-sensitive than among salt-resistant individuals. Finally, salt-sensitive individuals manifested a greater rise in blood pressure during exercise than salt-resistant individuals and a greater frequency of silent myocardial ischemia than salt-resistant individuals.…”

“…[18][19][20] Thus, a close relation may exist between salt sensitivity, microalbuminuria and cardiovascular events.…”

Effect of aerobic exercise training on blood pressure sensitivity to dietary sodium in older hypertensives

“…However, Na þ sensitivity has been linked to a number of metabolic and physiologic abnormalities such as albumin excretion, 16,17 left ventricular hypertrophy 18,19 and dyslipidaemia. 20 In a crosssectional study in Japanese hypertensives, cardiovascular events were found to be twice as common among Na þ sensitive hypertensives as among Na þ resistant hypertensives.…”

Participation of renal and circulating endothelin in salt-sensitive essential hypertension

“…There is evidence that salt-sensitive hypertensive patients exhibit excess prevalence or severity of left ventricular diastolic dysfunction 17 and hypertrophy 18 (perhaps linked to decreased nocturnal 'dipping' of BP 19 ) and increased incidence of stroke 20 and severity of microalbuminuria. 21 This end-organ damage pattern resembles that of saltsensitive hypertensive rats, such as DOC-salt and Dahl-salt-sensitive (SS). Most recently, Weinberger and co-workers have provided evidence that salt-sensitivity of BP of normotensive individuals carries with it the same detrimental long-term prognosis (mortality) as hypertension in salt-resistant patients.…”