Estimating Dietary Protein Intake in Peritoneal Dialysis Patients: The Effect of Ethnicity

Kidney dialysis patients with sarcopenia have increased mortality. Clinical guidelines recommend peritoneal dialysis (PD) patients have a target daily protein intake to prevent sarcopenia. Protein intake is estimated from total daily urea losses in urine and peritoneal dialysate to assess the protein equivalent of nitrogen appearance rate adjusted for body weight (nPNA). Dietary habits differ among ethnic groups, so we reviewed nPNA and body composition in a multi-ethnic PD population. Body composition was measured with multifrequency bioimpedance in 598 patients (301 white, 136 black, 123 South-Asian, and 38 Asian-Pacific). South-Asians had a lower nPNA compared with white and black individuals (Randerson 0.80 ± 0.21 vs 0.88 ± 0.24 and 0.85 ± 0.24 g/kg/day, Blumenkrantz 0.97 ± 0.14 vs 1.04 ± 0.22 and 0.99 ± 0.22 g/kg/day, Bergström 0.87 ± 0.4 vs 0.95 ± 0.24 and 0.92 ± 0.24 g/kg/day all p < 0.001). South-Asians had lower weights (68.9 ± 14.9 vs 74.4 ± 16.6 and 73.5 ± 16.3 kg, p < 0.001), and although of similar body mass index (25.9 ± 4.9 vs 28.5 ± 4.9 and 26.5 ± 5.2 kg/m²), had both lower skeletal muscle and appendicular muscle mass indexed for height (9.08 ± 1.45 vs 9.89 ± 1.62 and 10.1 ± 1.85, p < 0.001; and 6.95 ± 1.39 vs 7.68 ± 1.48 and 7.67 ± 1.58 kg/m²p < 0.01). South-Asian patients had a lower calculated basal metabolic rate (BMR) (1,358 ± 218 vs 1,487 ± 257 and 1,489 ± 271 kcal/day, p < 0.001).Asian PD patients, particularly South-Asians, have lower dietary protein intakes when calculated by nPNA. However, South-Asians had lower measured muscle mass and calculated BMR. As such, dietary protein intake targets derived from studies in 1 ethnic group are not necessarily applicable for all patients, as those with less muscle mass and lower BMR may well need less daily protein intake to maintain homeostasis.