Relationship between Hypertension and Renal Function and Its Therapeutic Implications in the Elderly

Abstract

The kidney is an important target of hypertension-induced organ damage. Recent long-term observation studies have documented that in individuals, without primary chronic renal disease, a very significant relationship exists between hypertension and impaired renal function, elderly hypertensives having a particularly worse prognosis. The hallmark of hypertensive renal injury is thought to be a progressive increase in intrarenal vascular resistance. The alterations in renal hemodynamics are accentuated in elderly patients with essential hypertension, pointing to a greater vulnerability of the senescent kidney to superimposed injury such as high blood pressure. Treatment of elevated blood pressure in the elderly therefore not only reduces cardiovascular morbidity and mortality, but also reduces the incidence of renal failure as a consequence of hypertension-induced damage.

ACCF/AHA 2011 Expert Consensus Document on Hypertension in the Elderly

“…147 The aging kidney is characterized by progressive development of glomerulosclerosis and interstitial fibrosis, which is associated with a decline in GFR and reduction of other renal homeostatic mechanisms. 147,148 Age-associated declines in membrane sodium/ potassium-adenosine triphosphatase may also contribute to geriatric hypertension because this results in increased intracellular sodium that may reduce sodium-calcium exchange and thereby increase intracellular calcium and vascular resistance. Reductions in cellular calcium efflux caused by reduced calcium-adenosine triphosphatase activity may similarly increase intracellular calcium and vascular resistance.…”

“…149 Latent volume expansion in the elderly also contributes to suppression of plasma renin activity and low aldosterone levels. 148 Renal hemodynamics are impaired in elderly patients with untreated ISH. Lower GFR and effective renal plasma flow characterize the older hypertension patient with a BMI Ͼ26.5 kg/m 2 .…”

“…155 The capacity of the kidney to excrete a sodium load is impaired with age, contributing to BP elevation. 148,156 Increased fractional reabsorption of sodium in the proximal tubule in the elderly may contribute to their tendency to exhibit an expanded sodium space resulting in salt-sensitive BP, and eventually fluid overload. 148,156 There is a significant positive association between 24-hour sodium excretion as well as urinary sodium/potassium ratio and SBP.…”

“…148,156 Increased fractional reabsorption of sodium in the proximal tubule in the elderly may contribute to their tendency to exhibit an expanded sodium space resulting in salt-sensitive BP, and eventually fluid overload. 148,156 There is a significant positive association between 24-hour sodium excretion as well as urinary sodium/potassium ratio and SBP. 157 The relation between sodium excretion and SBP is stronger for older than younger adults, perhaps reflecting longer exposure with aging or diminished capacity to handle sodium.…”

ACCF/AHA 2011 Expert Consensus Document on Hypertension in the Elderly

“…The aging kidney is characterized by progressive development of glomerulosclerosis and interstitial fibrosis, which is associated with a decline in GFR and reduction of other renal homeostatic mechanisms (147,148). Age-associated declines in membrane sodium/potassium-adenosine triphosphatase may also contribute to geriatric hypertension because this results in increased intracellular sodium that may reduce sodiumcalcium exchange and thereby increase intracellular calcium and vascular resistance.…”