Zinc as a marker of nutrition in continuous ambulatory peritoneal dialysis patients

Our aim was to show, in continuous ambulatory peritoneal dialysis (CAPD) patients, the relationships between zinc (serum level and dietary intake) and adequacy and duration of CAPD, age, and measures of nutrition. Serum zinc (12.2 +/- 1.8 mumol/L) was not significantly related to dietary zinc intake (9.9 +/- 2.5 mg daily), but depended on daily instilled (r = -0.331, p < 0.05) and effluent (r = -0.311, p < 0.05) dialysate volumes and on patient age (r = -0.304, p < 0.05). Positive correlations were seen between serum zinc level and laboratory (but not anthropometric) markers of nutrition: prealbumin (r = 0.349, p < 0.05), iron (r = 0.447, p < 0.05), transferrin saturation [(TSAT) r = 0.374, p < 0.05]. Additionally, zinc intake was positively related to serum ferritin level (r = 0.370, p < 0.05). Serum zinc level positively influenced blood morphology [correlation with hemoglobin (r = 0.287, p < 0.05) and mean corpuscular hemoglobin concentration (r = 0.361, p < 0.05)]. Zinc intake showed negative correlations with serum levels of total cholesterol (r = -0.373, p < 0.05) and vitamin E (r = -0.504, p < 0.05), and a positive correlation with HDL: total cholesterol ratio (r = 0.338, p < 0.05). Mean values of three latter parameters were out of the normal limits (total cholesterol: 219.2 +/- 47.0 mg/dL; vitamin E: 1.91 +/- 0.82 mg/dL; HDL: total cholesterol ratio: 16.7 +/- 5.1). We conclude that, in CAPD patients, zinc is a marker of nutrition showing beneficial effect on serum iron parameters, blood morphology, lipid profile, and elevated vitamin E concentration. Zinc supplementation is needed for approximately 16% of CAPD patients, especially older patients and those requiring higher dialysate volumes.