Nutritional Therapy of Chronic Renal Failure

IIiII!!!!!!!

AMERICAN

..... The National Kidney Foundation

KIDNEY DISEASES

VOL. II, NO.5, MARCH 1983

JOURNAL OF

The Official Journal of

Nutritional Therapy of Chronic Renal Failure

O

NE OF THE FIRST commissioned reviews to appear in this journal concerned nutritional aspects of chronic renal failure (Walser M: Nutritional management of chronic renal failure. Am J Kid Dis 1:261-275, 1982). This contribution by Dr. Walser was a scholarly discussion of the metabolic derangements and protein requirements for patients with significant renal insufficiency . In the same issue of the journal Dr. John P . Hayslett was guest editor of a controversy entitled; " Can the course of chronic renal disease be modified by therapeutic intervention? " It has been recognized since the early reports from Giordano 1 and Giovannetti and Maggiore 2 that by restricting dietary protein to that of high biologic value, the symptoms associated with uremic syndrome can be ameliorated. This concept has now moved from symptom amelioration to the possibility of decelerating the rate of deterioration of renal function in patients with chronic renal failure. The scientific basis for the benefit of protein restriction has been rejuvenated by observations reported by Hostetteret aI. 3 Using an animal model containing a remnant kidney in which renal failure associated with elevated blood pressure is a predictable outcome, these investigators demonstrated that the rate and severity of the expected uremia and hypertension can be strikingly modified in animals receiving restricted protein diets. They also separated the effect of protein restriction from that of phosphorous; the latter has been recognized to be a significant contributor to the rate of both experimental and clinical deterioration of renal function. 4 It was natural that extension of these observations into patients with chronic renal failure would occur, and recently, Maschio et al. 5 reported such a slowing of the rate of renal function deterioration . Because of the great importance of these obser-

vations for patients with chronic renal failure, it is natural that studies directed at nutritional epidemiology will be proposed. Nephrologists are fortunate in having a group of clinical nutritionists who have developed a substantial data base concerning the nutritional needs and utilization of nutrients by patients with impaired renal function. While most of the effort has been concentrated on patients after they have become candidates for renal replacement therapy, this new information suggests that interest will shift to earlier stages of renal failure. Such a shift is justified since these earlier stages promise to be particularly fruitful for investigation because of their pathophysiologic implications . Equally appealing is the substantial cost savings that would result if the rate of functional deterioration in patients with progressive renal failure could be substantially delayed , or even prevented , from reaching end-stage renal disease . This shift would place a premium on the nephrologist's knowledge concerning clinical nutrition . While medical schools provide ample education in the area of nutritional biochemistry, the effect of energy sources, and the interaction with various minerals, the teaching of clinical nutrition is neglected . With solid evidence that nutritional modifications could materially alter the outcome of a chronic disease , the impetus for more emphasis in medical school curriculum would be supplied . Finally , as one views the concerns expressed by the national health leadership concerning the exorbitant costs of treating end-stage renal disease by current technology, the potential cost savings of dietary manipulation are so great that they, of themselves , would provide adequate impetus for further study. While behavior modifications of a patient's dietary habits are difficult, they pale in comparison to the lifestyle changes that chronic dialysis necessitates or the inconveniences and

American Journal of Kidney Diseases, Vol. II , No.5, March 1983

497

GEORGE A. PORTER

498

complications associated with successful renal transplantation . While the zealots will promise more than can be delivered, the potential for such dietary intervention is so great that we all must cooperate in the critical studies that are required . The existence of medical review committees as significant components of the end-stage renal disease networks might be a focal point for initiating such nutritional epidemiology. While it is true that the patients enrolled in current ESRD programs are well beyond

inclusion in the study group desired, the providers who make up the network are clearly the phy.sicians of responsibility for the patient population under discussion. It would seem an excellent investment on the part of the federal government and the networks if the proposed correlation betwejiln dietary habits and rate of deterioration of re.&al function could be confirmed in a pre-ESRD population . George A. Porter, M ,D . Ediior

REFERENCES 1. Giordano C: Use of exogenous and endogenous urea for protein synthesis in normal and uremic subjects. J Lab Clin Med 62:321-246, 1963 2. Giovannetti S, Maggiore Q: A low-nitrogen diet with proteins of high biological value for severe uraemia. Lancet I: 1000~ 1003 , 1964 3. Hostetter TH, Olson JL , Rennke HG, et aI: Hyperftltration

in remnant nephrons: Apotential adverse response to renal ablation. Am J Physiol 241:F85-F93, 1981 4. Ibels LS, Alfrey AC, Haut L, et aI: Preservation of function in experimental renal disease by dietary phosphorous.· restriction . N Engl J Med 298: 122- 126, 1978 5 . Maschio G, Oldrizzi L, Tessitore N, et aI : Effect!pof dietary protein and phosphorous restriction on the progrescion of early renal failure . Kid Intern 22:371 - 376 , 1982