Dialysis & TransplantationVolume 36, Issue 10 p. 518-523 D&T ReportFree Access The D&T Report First published: 03 October 2007 https://doi.org/10.1002/dat.20178AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Reports of malnutrition in patients with chronic kidney disease (CKD) vary: Its prevalence ranges anywhere from 12% to 70% of the patient population, depending on disease stage, severity, and who you ask. While it has multiple causes, most relate to the metabolic changes associated with CKD and the notoriously poor appetite many kidney patients experience. Literature on the effect of nutritional repletion in CKD patients as it relates to their prognosis is sparse. There are many different ideas about the best ways to measure nutritional status, and how and if improving it will help survival rates in these patients. We investigate some of these differing opinions that make this issue so complex. Malnutrition in the CKD Patient Nutritional status, generally in the form of serum albumin, is an important marker. “After almost three decades of research, we have not been able to find anything that's a stronger predictor of survival,” says Kamyar Kalantar-Zadeh, MD, PhD, director of the dialysis expansion program and epidemiology, division of nephrology and hypertension, Harbor-UCLA Medical Center, Los Angeles. “Yet today there are still no clear-cut guidelines for improving nutritional status in dialysis patients.” Few renal patients have severe malnutrition, but “a mild decrease in serum albumin, for example, is quite common,” says Marsha Wolfson, MD, senior medical director of nephrology for Ortho Biotech Clinical Affairs in Bridgewater, N.J. Patients may suffer from one of two basic types of malnutrition: protein deficiency alone, or a combined lack of protein and energy or calories. The relative prevalence of the two types is hard to determine, says Jordi Goldstein-Fuchs, DSc, RD, kidney nutrition specialist at Sparks Dialysis, Sparks, Nev., and editor-in-chief of the Journal of Renal Nutrition. “In my practice, I see people who, for example, can preserve albumin while being wasted.” However, hemodialysis itself contributes to protein wasting: Patients can lose 10–12 grams of free amino acids per treatment, and peritoneal dialysis is associated with losses of whole protein.1 Nutritional deficiency doesn't develop overnight. It is a slow, insidious process and can begin relatively early in CKD, warns Linda McCann, RD, CSR, LD, senior director of quality for Satellite Healthcare in Mountain View, Calif. The changes may be subtle at first; often a drop in dietary intake is the first signal that anything is amiss. “But eventually [a patient's] protein stores, tissue stores, and visceral protein indicators begin to drop as well,” says McCann. Unfortunately, if this process has already started by the time the patient comes to dialysis, it is harder for him or her to bounce back. How Do We Measure Malnutrition? KDOQI clinical guidelines recommend three categories of measurement for patients with chronic renal failure (see Table I). However, adding to the complexity of the problem is the fact that a single parameter, like hypoalbuminemia, is not sufficient for a diagnosis of malnutrition. “Albumin can be low due to other factors such as excess fluid imbalance, nephrotic syndrome, and inflammation. There really isn't one nutrition parameter that can stand alone to define malnutrition,” says McCann. The diagnosis is made by examining a combination of factors, ranging from laboratory values to clinical signs and symptoms, as well as food intake. Serum albumin is certainly one measure, and in some cases, knowing the patient's prealbumin, or transthyretin, status can be helpful as well, as it has a much shorter half-life than albumin. Prealbumin “can be a good indication of the protein turnover,” says Dr. Goldstein-Fuchs. Table I. KDOQI-Recommended Measures for Monitoring the Nutritional Status of Patients on Maintenance Dialysis Other nutrients, most notably phosphorous and potassium, are closely related to overall nutrient intake and can also be good indicators of a patient's nutritional status. It is important to include a review of these nutrients when evaluating intake, says McCann. People with CKD often experience changes in appetite or may be prone to early satiety, nausea, or vomiting, so often the best assessment is the most straightforward: Take a look at the patient, or simply ask her about her appetite. Indeed, appetite may offer an important clue to prognosis. “CKD is associated with wasting of muscle mass and other body component stores—in other words, it is a wasting disease,” says Kamyar Kalantar-Zadeh. “One of the good things dialysis does is improve appetite. One of the first signs of success I see in people in the first three to six months of dialysis is that they start gaining weight.” Dr. Kalantar-Zadeh and his associates asked 331 outpatients on maintenance hemodialysis to rate their appetite. In general, the worse the patients rated their appetite, the higher the laboratory markers of malnutrition turned out to be. There was also a significant correlation between morbidity and mortality and poor appetite scores. Diminished appetite was associated with a hazard ratio of death of 4.74 (p = 0.001). To put it another way, poor appetite was associated with a four-fold increase in mortality and a higher risk of hospitalization, not to mention a significantly lower quality of life.2 Further Complexity Inflammation is an important confounding factor in the interpretation of nutritionrelated laboratory values. “Malnutrition has a strong association with inflammation,” says Dr. Kalantar-Zadeh. Patients in the aforementioned study who rated their appetite as poor had higher levels of pro-inflammatory cytokines than did patients with better appetites. In fact, illness and inflammation may be more important determinants of hypoalbuminemia than poor eating habits in patients with these conditions, says William A. Mitch, MD, chair of the nephrology department at Baylor College of Medicine in Houston, Texas. “Kidney failure and the complications of kidney disease stimulate mechanisms that cause the loss of protein stores and a decrease in albumin synthesis.” Thus, if poor nutrient intake did not cause the problem, improving nutrient intake will not reverse it. “Low serum albumin should not automatically be equated with malnutrition,” he says. Possible Solutions In general, anything that helps depleted patients eat and gain weight should be encouraged. “The safest and most reliable methods are those that have been used for years,” says Dr. Wolfson. “Working with the patient and family to improve protein and energy intake are the most important first steps. Identifying causes of reduced intake, such as poor appetite, and treating those causes is also important.” In some cases, increasing dialysis can enhance appetite by reducing uremia and improving the feeling of well-being. Patients who need more aggressive treatment may benefit from supplementation with intradialytic parenteral nutrition (IDPN) or intraperitoneal nutrition (IPN), in which nutrients are infused either through an existing dialysis access site or as part of the daily peritoneal dialysis exchange. While IDPN and IPN have been associated with weight gain, visceral protein synthesis, and increased serum albumin, they may not be the entire answer: At least one recent study has shown that these techniques do not confer any advantage in survival or nutritional status over oral supplementation.3 Bottom Line Literature on the effect of nutritional repletion on CKD prognosis is still woefully scarce. “There have not been any well-designed studies to see if nutritional intervention improves survival,” said Dr. Kalantar-Zadeh. Dr. Goldstein-Fuchs adds that the development of more effective therapies hinges on learning which factors make the most difference, as that is still somewhat unclear. In short, she says, “More funding is needed for research.” D&T Briefs BUSINESS Renal Solutions and IBT to Collaborate on Artificial Kidney Renal Solutions, which provides sorbent therapy products and services for the treatment of chronic and acute renal failure, has signed a collaborative agreement with Innovative BioTherapies (IBT) and the University of Michigan to develop a wearable renal replacement device. Through the terms of the agreement, Renal Solutions and David Humes, MD, president and chief science officer, IBT, will explore the ways that sorbent therapy, which uses just 6 liters of drinking water to deliver a full dialysis treatment, can be combined with the stem-cell technologies of IBT and the University of Michigan to develop a highly portable, wearable device for renal replacement. The collaboration will evaluate the metabolic consequences of a renal tubule cell device, including measurement of inflammatory response. The data resulting from these studies will greatly assist both companies in moving forward with plans for a wearable renal replacement device. FDA Clears Gambro Machines for U.S. Market The FDA has lifted the import alert it issued in January 2006 that prevented the import of Gambro's Phoenix and Prismaflex machines into the United States. The FDA says that the company has successfully addressed the observations cited in its warning letter. Gambro will begin selling Phoenix machines to U.S. customers, and will introduce a significant software upgrade for Prismaflex later this year. When this upgrade is cleared, Gambro will re-introduce Prismaflex to the U.S. market. ASSOCIATIONS NKF Updates Anemia Guidelines After an extensive review of results from six new randomized controlled trials comparing risks and benefits of a range of target hemoglobin (Hgb) levels in chronic kidney disease (CKD) patients, the National Kidney Foundation KDOQI work group has issued an official update of its 2006 Clinical Practice Guidelines on Anemia and CKD. A key aspect of the update is its emphasis on clinical judgment and the needs of the individual patient receiving erythroerythropoiesis stimulating agent (ESA) therapy. In the new statements, the work group states that the selected Hgb target generally should be in the range of 11.0 to 12.0 g/dL. However, due to natural fluctuations, actual Hgb results will vary widely from targets, the work group says. Based on their analysis, the work group upgraded one of its opinion-based statements to an evidence-based guideline recommending that, in dialysis and nondialysis CKD patients receiving ESA therapy, the Hgb target should not be higher than 13.0 g/dL. The updated guidelines are available at www.kidney.org. PATIENTS DaVita Contest Accepting Entries The DaVita “Who's Your Kidney Idol” contest is now accepting entries. People are invited to nominate a kidney patient, caregiver, friend, spouse, healthcare professional, or anyone in the CKD or dialysis community who has made a difference to those around them. Each entry should be a 250-word essay that describes the nominee, and can be submitted online through November 6. Visit www.davita.com for more information on how you or your patients can submit an entry. References 1 Ikizler TA, Flakoll PJ, Parker RA, Hakim RM. Amino acid and albumin losses during hemodialysis. Kidney Int. 1994; 46(3): 830– 837. CrossrefCASPubMedWeb of Science®Google Scholar 2 Kalantar-Zadeh, K, et al. Appetite and inflammation, nutrition, anemia, and clinical outcome in hemodialysis patients. Am J Clin Nutr. 2004; 80: 299– 307. CrossrefCASPubMedWeb of Science®Google Scholar 3 Cano NJ, et al. Intradialytic parenteral nutrition does not improve survival in malnourished hemodialysis patients: a 2-year, multicenter, prospective, randomized study. J Am Soc Nephrol. 2007; 18(9): 2583– 2591. CrossrefCASPubMedWeb of Science®Google Scholar Volume36, Issue10October 2007Pages 518-523 ReferencesRelatedInformation