Nephrol Dial Transplant (2004) 19: 1331-1332
Nephrol Dial Transplant Vol. 19 No. 5 © ERA-EDTA 2004; all rights reserved
The clinical significance of aldosterone in ESRD: Part II
Sir,We would like to congratulate Epstein for his excellent review of the rapid advances in our understanding of the non-classical effects of aldosterone [1]; however, allow us to add one small word of caution. While the role of aldosterone in endothelial dysfunction is clear and its deleterious effect on survival of patients with cardiovascular disease is undisputed, its clinical significance and effect on survival is not yet demonstrated in patients with end-stage renal disease (ESRD). As recently noted in this Journal, often risk factors for overall and cardiovascular mortality in the general population, such as a high cholesterol [2], obesity [2,3] or hypertension [3,4] are either not found to be risk factors or are paradoxically associated with improved survival. Hyperkalaemia with resulting sustained elevation of aldosterone levels in haemodialysis patients may be an important risk factor in their accelerated atherosclerosis; but perhaps it is not. Over a decade ago, we evaluated the significance of serum aldosterone levels upon non-renal potassium elimination in patients on dialysis. We found a group of patients who were unable to mount an aldosterone response to hyperkalaemia who maintained persistently low levels of aldosterone despite a potassium challenge [5]. Most of the patients in that study are now deceased. When we recently evaluated the data, we found that the effect of the inability to secrete aldosterone appeared not to be protective. Patients with higher aldosterone levels tended to have longer survival (Figure 1).
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Although we did not find that the aldosterone level was as significant as dietary restriction in potassium homeostasis, it is possible that some of the benefit may have been due to the aldosterone itself. Of course, there were confounding factors. The patients who were unable to mount an aldosterone response to hyperkalaemia were usually those with hyporeninaemic hypoaldosteronism; who, in turn, were more likely to have ESRD diagnoses of diabetes and sickle cell anaemia. We already knew that patients with those diagnoses do not have prolonged survival on dialysis. Therefore, it does not necessarily mean that high aldosterone levels improve the survival of haemodialysis patients, but may merely mean that those with the diagnoses that are prone to have low levels have poor survival. The effect may be similar to those recently related [3] for the apparently positive effects of obesity and hypertension. It may not be that obesity prolongs the survival of dialysis patients, but merely that patients who are thin from malnutrition merely skew the data to look that way. Like the author of that editorial comment, I would suggest that a reasonable and prudent approach to the subject would be to reserve judgement at present and wait for further studies.
Conflict of interest statement. None declared.
Hypertension, Nephrology, Dialysis and Tranplantation, Inc Opelika Alabama USA Email: hndt512{at}bellsouth.net
References
- Epstein M. Aldosterone receptor blockade and the role of eplerenone: evolving perspectives. Nephrol Dial Transplant 2003; 18: 1984–1992
[Free Full Text] - Degoulet P, Legrain M, Reach I, Aime F, Devries C, Rojas P, Jacobs C. Mortality risk factors in patients treated by chronic hemodialysis. Nephron 1982; 31: 103–110[Web of Science][Medline]
- Salahudeen AK. Is it really good to be fat on dialysis? Nephrol Dial Transplant 2003; 18: 1248–1252
[Free Full Text] - Duranti E, Imperiali P, Sasdelli M. Is hypertension a mortality risk factor in dialysis? Kidney Int Suppl 1996; 55: S173–S174[Medline]
- Diskin CJ, Thomas CE, Stokes TJ. The clinical significance of aldosterone in ESRD. In: Abstracts of the XXVII Congress of the EDTA-European Renal Association, Vienna, Austria. 1990; 128
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