ATLANTA—Low plasma ascorbic acid (AA) concentrations are associated with increased resistance to erythropoietin (EPO), researchers reported at the American Society of Nephrology’s Kidney Week 2013 meeting.

In end-stage renal disease, one cause of EPO resistance is functional iron deficiency. Iron stores are normal, the researchers explained, but erythropoiesis is less effective due to decreased iron delivery to the bone marrow.

William D. Sirover, MD, of Cooper Medical School of Rowan University in Camden, N.J., Garry Handelman, PhD, of University of Massachusetts Lowell, and colleagues analyzed hematologic data from 179 HD patients with ferritin levels above 100 ng/mL. Over the entire plasma AA range (1.78-409.3 μM), AA did not correlate with EPO resistance, but in 148 patients with plasma AA levels in the physiologic range (0-100 μM), plasma AA correlated inversely with EPO resistance and correlated directly with transferrin saturation, but did not correlate with ferritin.

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“In patients with low plasma AA levels, use of supplemental AA may treat functional iron deficiency and EPO resistance by increasing iron availability,” the researchers concluded.