Iron absorption after single pharmacological oral iron loading test in patients on chronic peritoneal dialysis and in healthy volunteers

Objective: Oral iron is poorly absorbed in chronic dialysis patients. We te sted the hypothesis that a superpharmacologic dose of iron sulfate (260 mg elemental iron) administered on an empty stomach results in significant iro n 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 n ormal control subjects. Method: All subjects ingested a single dose of 4 tablets of iron sulfate (2 60 mg elemental iron total) in the morning while fasting. Outcome Measures: Serum iron concentrations at baseline, and at 2 and 4 hou rs after the oral dose were compared between the two groups. Results: The control group showed a significant rise in mean [+/- standard error (SE)I serum iron concentration, from a baseline value of 76.5 +/- 7 m ug/dL to 191 +/- 10.5 mug/dL at 2 hours and to 190 +/- 24 mug/dL at 4 hours . This result represents a percentage rise of 164% +/- 32% at 2 hours and 1 52% +/- 28.5% at 4 hours. In the PD patients, a significant rise in serum i ron concentration was also seen, from a baseline value of 64 +/- 8 mug/dL t o 130 +/- 3 mug/dL at 2 hours and 111 +/- 18 mug/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 c ontrol subjects at those time points. None of the PD patients experienced g astrointestinal side effects; 4 control subjects experienced mild side effe cts. Conclusion: Despite impaired oral iron absorption in chronic dialysis patie nts, a large pharmacologic dose given orally can result in significant iron absorption and may prove to be a more efficient means of oral iron supplem entation therapy in these patients.