Anemia of inflammatory disease in the dog: availability of storage iron in inflammatory disease.

The iron-chelating agent deferoxamine (DF) was administered as a single dose and also daily over a prolonged period to evaluate availability of storage iron in dogs with induced anemia of inflammatory disease. In a 6-hour period, total urinary ferrioxamine (measured as urinary iron) excretion in controls was 251.22 +/- 119.68 microgram (mean +/- 1 SD), a 5.32 +/- 2.64-fold increase over prechelation values. In anemia of inflammatory disease-affected dogs, excretion was diminished to 115.67 +/- 34.86 microgram, a 2.87 +/- 1.10-fold increase, indicating a restricted iron excretion and sequestration of iron in a less soluble, less chelatable form. During prolonged DF administration, a pattern of increasing total urinary iron excretion was observed. This pattern is consistent with iron being stored as an insoluble polynuclear hydroxide in protein of ferritin and hemosiderin. The increase in hemoglobin and serum iron concentrations during prolonged DF administration indicates that increased iron stores are present, but in a less labile form. During the process of chelation, iron is converted to a more readily utilized state, and the increased availability of iron promotes hemoglobin synthesis. Thus, storage iron in the form of hemosiderin and ferritin is released to the metabolizable pool.