Zinc levels after iron supplementation in patients with chronic kidney disease.
OBJECTIVE
The goal of this study was to evaluate the effects of iron supplementation on zinc distribution in nondialyzed chronic kidney disease (CKD) patients.


METHODS
Prospective nonrandomized observational study.


METHODS
Outpatients of the Nephrology Division at Federal University of São Paulo.


METHODS
Zinc and iron status of 38 nondialyzed patients (63% male; creatinine clearance, 34.5+/-13.3 mL/min/1.73 m2) was evaluated before and after 3 intramuscular injections of 100 mg iron each.


METHODS
The following parameters were analyzed: erythrocytes and plasma zinc, zinc protoporphyrin (ZPP), plasma ferritin, transferrin saturation (TFS), and total iron. The patients' diets were analyzed by the Association of Official Analytical Chemists method for macronutrients, and neutron activation analysis was used for iron and zinc concentration determinations.


RESULTS
Ferritin and TFS increased from 86.3+/-67.5 ng/mL to 105.4+/-63.7 ng/mL and from 19.5+/-7.4% to 23.2+/-6.7% (P <.05), respectively, after iron supplementation. Absolute iron deficiency (ferritin <100 microg/L and TFS <20%) was present in 41% of the patients and decreased to 15.7% after iron treatment. In comparison with baseline values (76.4+/-16.7 microg/dL), there were no significant changes in plasma zinc levels, but after supplementation the number of patients with low plasma zinc levels decreased from 46.1% to 23.7% (P =.08). At baseline, erythrocyte zinc was 49.0+/-7.6 microg Zn/gHb, and 76.3% of the patients had high erythrocyte zinc concentration. After iron treatment, erythrocyte zinc decreased to 45.5+/-7.3 microg Zn/gHb (P =.001). No significant change was observed in ZPP concentration. The analysis of the diet showed energy and protein intakes of 26.2+/-7.1 kcal/kg/day and 0.89+/-0.2 g/kg/day, respectively, and a low intake of both iron and zinc.


CONCLUSIONS
This study suggests that iron deficiency may contribute to the inadequate distribution of zinc in patients with CKD and that iron supplementation may decrease the abnormal elevated erythrocyte zinc levels of these patients.
Mafra
Denise
D
Cuppari
Lilian
L
Fávaro
Déborah I T
DI
Cozzolino
Slvia M F
SM
D000293:Adolescent; D000328:Adult; D000368:Aged; D004032:Diet; D004912:Erythrocytes / Q000737:chemistry; D005260:Female; D005293:Ferritins / Q000097:blood; D006801:Humans; D007273:Injections, Intramuscular; D007501:Iron / Q000008:administration & dosage* / Q000097:blood; D000090463:Iron Deficiencies; D019266:Iron, Dietary / Q000008:administration & dosage; D007676:Kidney Failure, Chronic / Q000188:drug therapy / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011524:Protoporphyrins / Q000097:blood; D014168:Transferrin / Q000032:analysis; D015032:Zinc / Q000008:administration & dosage / Q000097:blood*
D019266:Iron, Dietary; D011524:Protoporphyrins; D014168:Transferrin; C017803:zinc protoporphyrin; D005293:Ferritins; D007501:Iron; D015032:Zinc