Iron Absorption after Single Pharmacological Oral Iron Loading Test in Patients on Chronic Peritoneal Dialysis and in Healthy Volunteers

Abstract

Objective Oral iron is poorly absorbed in chronic dialysis patients. We tested the hypothesis that a superpharmacologic dose of iron sulfate (260 mg elemental iron) administered on an empty stomach results in significant iron absorption in these patients. Design A prospective open controlled trial. Setting Outpatient department of a university hospital. Patients Nine stable chronic peritoneal dialysis (PD) patients and seven normal control subjects. Method All subjects ingested a single dose of 4 tablets of iron sulfate (260 mg elemental iron total) in the morning while fasting. Outcome Measures Serum iron concentrations at baseline, and at 2 and 4 hours after the oral dose were compared between the two groups. Results The control group showed a significant rise in mean [± standard error (SE)] serum iron concentration, from a baseline value of 76.5 ± 7 μg/dL to 191 ± 10.5 μg/dL at 2 hours and to 190 ± 24 μg/dL at 4 hours. This result represents a percentage rise of 164% ± 32% at 2 hours and 152% ± 28.5% at 4 hours. In the PD patients, a significant rise in serum iron concentration was also seen, from a baseline value of 64 ± 8 μg/dL to 130 ± 3 μg/dL at 2 hours and 111 ± 18 μg/dL at 4 hours. This result represents a percentage rise of 105% ± 29% at 2 hours and 77% ± 23.5% at 4 hours. However, the absolute change in serum iron concentration in PD patients at 2 and 4 hours was approximately equal to 50% of the change in control subjects at those time points. None of the PD patients experienced gastrointestinal side effects; 4 control subjects experienced mild side effects. Conclusion Despite impaired oral iron absorption in chronic dialysis patients, a large pharmacologic dose given orally can result in significant iron absorption and may prove to be a more efficient means of oral iron supplementation therapy in these patients.