Is absorption of high-dose oral iron sufficient in peritoneal dialysis patients?

Iron supplementation plays a major role in erythropoietin-treated end-stage renal disease patients. For peritoneal dialysis (PD) patients, oral iron substitution is more convenient than intravenous therapy. However, disturbed iron absorption and adverse effects may be limiting factors for oral treatment. Nevertheless, we compared the response to a high-dose and low-dose oral iron absorption test between PD patients and healthy control subjects.

In 34 PD patients and 15 healthy control subjects, blood samples were taken at baseline as well as 2, 4, and 8 hours after oral intake of 4 tablets iron sulfate (105 mg elemental iron per tablet). In a subgroup of 6 PD patients and 6 control subjects, the oral iron absorption test was repeated using 1 tablet iron sulfate.

There was no significant difference in the increase in serum iron during the test between the two groups. As known for healthy subjects, iron absorption was significantly better in PD patients with absolute iron deficiency compared to those with functional iron deficiency. Iron-repleted PD patients showed the lowest iron absorption, indicating that a high dose of oral iron did not overwhelm the ability of the bowel tract to reject unneeded iron. Increasing the oral iron dose from 1 to 4 tablets was followed by a better response in a small subgroup of PD patients compared to control subjects. Side effects such as nausea and vomiting occurred more frequently during high-dose oral iron in control subjects than in PD patients (20% vs 8.8%).

High-dose oral iron is well absorbed in iron-depleted PD patients. This kind of oral iron therapy should be considered in some subgroups of PD patients with iron deficiency, particularly in those patients with poor vascularization of arm veins or intolerance to intravenous iron preparations.