THE NORMALIZED PROTEIN CATABOLIC RATE IS A FLAWED MARKER OF NUTRITIONIN CAPD PATIENTS

For both hemodialysis and CAPD patients nutrition has been linked to m ortality. Protein calorie malnutrition is present in 20 to 40% of CAPD patients. The normalized protein catabolic rate (NPCR), has been prop osed as a useful measure of dietary protein intake and ultimately nutr ition. However, the NPCR value has not been consistently predictive of outcome in CAPD patients. We have performed a cross sectional study o n 147 clinically stable CAPD patients, who had a mean dialysis duratio n 22 months, to evaluate the relationship between the NPCR and convent ional markers of nutrition. The NPCR was significantly correlated with normalized models of dialysis adequacy including KT/V (urea), total w eekly creatinine clearance and the dialysis index. A significant negat ive correlation was found between individual anthropometric measures a nd the NPCR. Using a composite nutritional index to nutritionally cate gorize our population we found a significantly higher NPCR value in th e severely malnourished group. The unadjusted protein catabolic rate ( PCR) was significantly correlated with individual nutritional measures and was significantly greater in the well-nourished group. The NPCR, obtained by dividing the PCR by body weight (itself a nutritional meas ure), is lowest in well-nourished or obese patients, and thus as a mar ker of nutrition may be flawed. The PCR has nutritional relevance, how ever, adjusting its value to take into account patient size will requi re prospective evaluation of the influence of small solute removal on body composition.