Independent effects of residual renal function and dialysis adequacy on dietary micronutrient intakes in patients receiving continuous ambulatory peritoneal dialysis.
BACKGROUND
Dialysis patients are at risk of vitamin and mineral deficiencies, not only because of losses during chronic hemodialysis or peritoneal dialysis but also because of low intakes.


OBJECTIVE
The objective was to determine the importance of urea clearance (calculated as K(t)/V) and residual renal function (RRF) in predicting micronutrient intakes in a large cohort of patients receiving continuous ambulatory peritoneal dialysis (CAPD).


METHODS
We conducted a survey of dietary intakes in 242 CAPD patients and divided them into 3 groups according to their weekly urea clearance and RRF: WD group (n = 84), a urea clearance >/= 1.7 and a glomerular filtration rate (GFR) >/= 1 mL x min(-1) x 1.73 m(-2); DD group (n = 71), a urea clearance >/= 1.7 and a GFR < 1 mL x min(-1) x 1.73 m(-2); and ID group (n = 87), a urea clearance < 1.7.


RESULTS
Most of the patients had intakes of water-soluble vitamins and minerals that were lower than the recommended dietary allowance; most intakes were significantly higher in the WD group than in the DD and ID groups, except those of niacin and calcium. After age, sex, body weight, and the presence of diabetes were controlled for, total weekly urea clearance and the GFR (but not peritoneal dialysis urea clearance) were significantly associated with intakes of vitamins A and C, the B vitamins, and minerals (calcium, phosphate, iron, and zinc). Low intakes of vitamins and minerals with low RRF and urea clearance were the result of reduced overall food intakes, except for thiamine, vitamin B-6, and folic acid, which were deficient in the diet.


CONCLUSIONS
Supplementation with most water-soluble vitamins and minerals, including iron and zinc, should be considered in CAPD patients, especially those with low RRF and low urea clearance. The optimal dose needs to be determined.
Department of Medicine & Therapeutics, Center for Nutritional Studies, Prince of Wales Hospital, Chinese University of Hong Kong. awang@cuhk.edu.hk
Angela Yee-Moon
AY
Wang
Mandy Man-Mei
MM
Sea
Ricky
R
Ip
Man Ching
MC
Law
Kai Ming
KM
Chow
Siu Fai
SF
Lui
Philip Kam-Tao
PK
Li
Jean
J
Woo
D000328:Adult; D000368:Aged; D003404:Creatinine / Q000378:metabolism; D004032:Diet; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008657:Metabolic Clearance Rate; D018977:Micronutrients / Q000008:administration & dosage*; D008875:Middle Aged; D008903:Minerals / Q000008:administration & dosage; D009748:Nutrition Disorders / Q000453:epidemiology; D018673:Nutrition Policy; D009752:Nutritional Status; D010531:Peritoneal Dialysis, Continuous Ambulatory; D012995:Solubility; D014508:Urea / Q000378:metabolism*; D014815:Vitamins / Q000008:administration & dosage
D018977:Micronutrients; D008903:Minerals; D014815:Vitamins; D014508:Urea; D003404:Creatinine