Doug Brunk is with the San Diego bureau of Elsevier Global Medical News. SAN DIEGO — An estimated glomerular filtration rate of less than 30 mL/min is associated with malnutrition in all ages, while an estimated GFR between 30 and 59 mL/min is associated with malnutrition only in people older than 60 years. Those are key findings from a study that compared the prevalence of malnutrition in the elderly with that of younger age groups and that compared the risk of malnutrition using estimated GFR (eGFR) estimated by creatinine and cystatin C-based equations. Researchers at Tufts Medical Center, Boston, examined the prevalence of malnutrition and its relationship to eGFR in 6,877 adults who participated in the National Health and Nutrition Examination Survey 1988-1994 (NHANES III). Malnutrition was defined as a Mini Nutritional Assessment (MNA) score of less than 56.7%. The investigators used the Modification of Diet in Renal Disease (MDRD) study equation and the Chronic Kidney Disease Epidemiology (CKD-EPI) equation to calculate glomerular filtration rate from serum creatinine readings. They also estimated GFR with a serum cystatin C equation adjusted for age, gender, and race. Cindy Huang, MD, a nephrology fellow at the medical center, reported in a poster at the annual meeting of the American Society of Nephrology that the prevalence of malnutrition increased with age in a stepwise fashion, from 9% in those aged 20-49 years to 12% in those aged 40-49, 15% in those 60-79, and 22% in those older than 80 years. By estimating GFR by serum creatinine alone, the researchers found that a level of 90 mL/min or greater was associated with malnutrition in the elderly, most likely due to the presence of sarcopenia. By estimating GFR by cystatin C alone, the researchers found that a level of 90 mL/min or greater was not associated with malnutrition in this population of patients, as cystatin C level is not affected by muscle mass.“Th “This has implications for [long-term care] in that physicians should continue to emphasize and maximize nutritional status in the face of even moderate degrees of renal dysfunction in nursing home patients to the degree possible,” commented Charles Cefalu, MD, CMD, of New Orleans. “This means providing calories and especially protein—but protein to the degree… that the aging kidneys can tolerate.”