Monitoring of iron requirements in renal patients on erythropoietin

We studied 38 patients (9 haemodialysis, 18 peritoneal dialysis,11 advanced renal failure) over the first 12 weeks of erythropoietintherapy. In 14 iron-overloaded patients (ferritin >500 µg/l)the haemoglobin (±SEM) increased from 6.74±0.27to 9.85±0.36 g/dl (P<0.0001) entirely by mobilizingiron reserves (reduced from 1,220±73 to 739±111mg, P<0.0001). In the 24 non-overloaded patients (ferritin<500µg/l) the haemoglobin rose similarly from 7.04±0.18to 10.70±0.36 g/dl (P<0.0001), partly from iron reserves(depleted from 200±74 to –44±77mg, P=0.016)and partly from oral iron supplements (305±110 mg). Inthe overloaded patients the ferritin declined from 1057 µg/l(geometric mean, range 504–3699) to 317 µg/l (42–1505,P<0.0001). In the non-overloaded patients it declined from82 µg/l (8–461) to 45 µg/l (5–379, P=0.016).The transferrin saturation (TS) in the overloaded patients appearedto decline from 38.3±7.2% to 24.0±3.7% but thiswas not statistically significant. In the non-overloaded theTS was unchanged (23.3±2.4 before and 28.1±3.6%after treatment). Considering all 38 patients together, thehaemoglobin correlated negatively with the ferritin (r=0.3731,P<0.001) but not with the TS. The TS correlated with theserum ferritin initially (r=0.75, P<0.001) but not afterthe first 4 weeks. At 12 weeks, eight of 15 patients with irondeficiency (ferritin<50 µg/l) had a TS >20%, whereastwo of five patients with persistent iron overload (ferritin>500 µg/l) had a TS <20%. We conclude that (a) inpatients with iron overload, stored iron is utilizable for erythropoiesis;(b) oral iron supplements are necessary and sufficient for mostpatients without iron overload; (c) the serum ferritin is abetter indicator of iron status than the TS for renal patientson erythropoietin.