Background: The etiology of chronic anemia in children with JRA is poorly understood. We utilized stable and radioactive Fe isotopes to determine Fe absorption, RBC incorporation and intraarticular deposition in children with JRA.

Subjects: 5 children (age range 3-17 yr) with polyarticular JRA(20 ± 12 months since diagnosis), of whom 3 were anemic (Hgb < 11 g/d1) and 5 healthy, age- and sex-matched children.

Interventions: 57Fe was given orally with vitamin C. Iron isotopes were given intravenously to determine RBC incorporation of absorbed Fe (58Fe) and joint deposition of Fe (59Fe). 59Fe was only given to subjects with JRA.

Results: RBC incorporation of the 58Fe in JRA subjects was 68± 19% of the dose compared to 83 ± 14% in healthy controls (p = 0.08). Fe absorption was 8 ± 7% in the 3 anemic JRA subjects compared to 23 ± 10% in the 3 age-matched controls (p = 0.10). Increased 59Fe deposition was seen in the diseased joint regions of 3 of the 4 JRA subjects given 59Fe.

Conclusion: Decreased Fe absorption and incorporation into RBCs demonstrate abnormal regulation of Fe metabolism in children with JRA. Excess Fe may be inappropriately deposited into affected joints. Oral Fe supplementation may not be effective in treating anemia in children with JRA.