Characteristics of Anemia and Iron Deficiency After Kidney Transplant

Numerous studies have shown that iron deficiency is common in patients with end-stage renal disease. However, change of iron deficiency after kidney transplant (KT) is not fully understood. This study was undertaken to examine sequential changes of iron level after KT.

A total of 1080 KT recipients enrolled in a multicenter observational cohort study between July 2012 and August 2018. A total of 786 patients with transferrin saturation and ferritin level at pretransplant and 1 year after KT were reviewed. Iron deficiency was defined as ferritin <200 ng/mL and total saturation of transferrin (TSAT) < 20%. Anemia was defined as hemoglobin (Hb) < 13 g/dL (male) or <12 g/dL (female).

Hemoglobin at 1 year after KT was higher than Hb at KT (13.64 [SD, 1.87] g/dL vs 10.53 [SD, 1.63] g/dL; P < .001). The TSAT decreased from baseline at 1 year after KT (33.89% [SD, 18.73%] vs 29.09% [SD, 14.54%]; P < .001), and ferritin level decreased from baseline at 1 year (190.63 [SD, 217.43] ng/mL vs 141.39 [194.25] ng/mL; P < .001). In patients with anemia at pretransplant, the group with anemia at 1 year after KT (persistent group) and the group without anemia at 1 year after KT (improved group) were compared. The persistent group showed higher pretransplant TSAT, lower 1-year TSAT, and lower estimated glomerular filtration rate at 1 year after KT than the improved group. In multivariate analysis, low ferritin at KT, low TSAT at 1 year, and high ferritin at 1 year were the risk factors for low Hb level at 1 year after adjusting multiple variables.

Anemia improved within 1 year after KT, although patients with iron deficiency increased. While ferritin reflected the inflammatory status, low TSAT at 1 year after KT was a risk factor for anemia at 1 year after KT.