Comprehensive suppression of the renin-angiotensin-aldosterone system in chronic kidney disease: covering all of the bases

Angiotensin II receptor blocker prevents upper gastrointestinal bleeding in hypertensive patients with chronic kidney disease not on dialysis

AIMS

Investigate if angiotensin II receptor blocker (ARB) decreases risk of upper gastrointestinal bleeding (UGIB) in hypertensive patients with chronic kidney disease (CKD) not on dialysis.

METHODS

All hypertensive patients with CKD not on dialysis in outpatient department of China Medical University Hospital from 2003 to May 2013 were enrolled. The risk of UGIB was analysed using Cox proportional hazard regression.

RESULTS

A total of 2744 hypertensive CKD patients including 1515 male and 1229 female, aged 64.9 ± 13.8 years old in a median of 1.9 (0.9-3.9) years were analysed. The incidence of UGIB was 4.5 per 100 patient-years. ARB was associated with a decreased risk of UGIB (p < 0.001) with an adjusted hazard ratio (HR) of 0.533 [95% confidence interval (CI) 0.404-0.703]. A history of UGIB, Helicobacter pylori infection, diabetes, lower estimated glomerular filtration rate, elevated blood urea nitrogen and decreased serum albumin were independently associated with an increased risk of UGIB.

CONCLUSIONS

Angiotensin II receptor blocker is associated with a decreased risk of UGIB in hypertensive CKD patients not on dialysis, independent of their renal function, history of gastrointestinal bleeding and nutrition status.

Aldosterone and progression of renal disease

PURPOSE OF REVIEW

The aim of this review is to look at the role of aldosterone in the progression of chronic kidney disease. The reduction of blood pressure and proteinuria in patients suffering from chronic kidney disease decreases the rate of disease progression. Suppression of angiotensin formation by angiotensin converting enzyme inhibitors and blockade of the angiotensin II receptor by angiotensin II type 1 antagonists are powerful therapeutic strategies that effectively lower blood pressure and slow the progression of renal disease. These therapies, however, provide only imperfect protection, since they cannot always prevent endstage renal failure.

RECENT FINDINGS

Aldosterone plays a significant role in the pathogenesis of arterial hypertension and renal disease. Angiotensin converting enzyme inhibitors and angiotensin II type 1 antagonists are incomplete in suppressing aldosterone production and 'aldosterone breakthrough' can be observed under continued treatment. Aldosterone blockade reduces blood pressure in virtually all patients with hypertension. In proteinuric patients, the addition of an aldosterone antagonist to an angiotensin converting enzyme inhibitor or to angiotensin II type 1 antagonists reduces proteinuria.

SUMMARY

The use of aldosterone antagonists in addition to either angiotensin converting enzyme inhibitors or angiotensin II type 1 antagonists in proteinuric patients reduces proteinuria, which may translate into preservation of the glomerular filtration rate in the longer term. Therefore, blockade of the aldosterone pathway may prove to be a beneficial therapy for chronic kidney disease.

Mechanisms of progression of chronic kidney disease

Chronic kidney disease (CKD) occurs in all age groups, including children. Regardless of the underlying cause, CKD is characterized by progressive scarring that ultimately affects all structures of the kidney. The relentless progression of CKD is postulated to result from a self-perpetuating vicious cycle of fibrosis activated after initial injury. We will review possible mechanisms of progressive renal damage, including systemic and glomerular hypertension, various cytokines and growth factors, with special emphasis on the renin-angiotensin-aldosterone system (RAAS), podocyte loss, dyslipidemia and proteinuria. We will also discuss possible specific mechanisms of tubulointerstitial fibrosis that are not dependent on glomerulosclerosis, and possible underlying predispositions for CKD, such as genetic factors and low nephron number.