Zinc Tolerance Test in Uremia

Abstract

The effects of ferrous sulfate and aluminum hydroxide on the oral zinc tolerance test after administration of 25 mg of elemental zinc as sulfate were studied in six hemodialysis patients and six normal controls. Fasting plasma zinc levels, the 2-hour plasma zinc peak, and the area under the plasma zinc curve were significantly lower in patients compared with values in controls (plasma zinc, 92 +/- 4 compared with 108 +/- 3 micrograms/dL, p less than 0.025; 2-hour plasma zinc peak, 159 +/- 8 compared with 228 +/- 17 micrograms/dL, p less than 0.025; and area under the curve, 193 +/- 41 compared with 316 +/- 39 micrograms h/dL, p less than 0.025). Ferrous sulfate (300 mg orally), when administered along with zinc sulfate, decreased the area under the curve significantly (in patients by 28%, in controls by 40%) in comparison with the results obtained when zinc sulfate was given alone. When 30 mL of aluminum hydroxide was administered orally with zinc sulfate, the area under the curve decreased by 60% in controls and 75% in patients (p less than 0.005). These results confirm the presence of diminished zinc absorption in patients with renal failure and show that ferrous sulfate and aluminum hydroxide, which worsen this defect, also impair zinc absorption in normal subjects.

Avaliação nutricional de pacientes em hemodiálise

“…De fato, Abu-Hamdan et al 42 já tinham evidenciado deficiência de absorção de zinco em pacientes dialisados, além de relatarem agravamento dessa condição com o uso de sulfato ferroso e quelantes de fósforo.…”

Possible Site of Decreased Intestinal Zinc Absorption in Chronic Uremic Rats

“…The zinc metabolism is altered in chronic uremia, and it is not corrected by maintenance dialysis therapy [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]. Zinc supplementation has been shown to improve some abnormalities in uremic patients [8, 9, 10, 17].…”

“…The zinc tolerance test (ZTT), measuring the change in the plasma zinc concentration after oral zinc administration, was used as a simple, indirect measure of zinc absorption from the gastrointestinal tract [20]. The ZTT has been widely used both in normal subjects [20, 21, 22, 23]and in patients with various diseases [24, 25, 26, 27]as well as chronic uremia [11, 28, 29]to assess the effect of a disease process on zinc absorption. The present study is the first to report on the employment of the ZTT to estimate the intestinal zinc absorption in a rat model of chronic uremia.…”

Zinc Absorption in Haemodialysis Patients

“…In one study by Antoniou et al, III reduced plasma zinc responses in haemodialysis patients were increased when patients are treated with vitamin D analogues. On the other hand Abu-Hamdan et al 17 observed similarly improved responses when coexisting treatment with oral aluminium hydroxide and iron salts was withdrawn.…”

“…IS We have no cause to doubt the compliance of our subjects, and we suggest that our findings are the result of a defective intestinal uptake of zinc by the dialysis patients participating in our investigations. It is only possible to speculate on the cause of this putative malabsorbative state, but the previously described reports of Antoniou et al I" and AbuHamdan et al 17 suggest that the known defects of vitamin 0 metabolism in uraemia. and the conventional use of iron supplements and aluminium hydroxide-base phosphate binders.…”