Impact of C-reactive protein on absolute reticulocyte count in haemodialysis patients: the role of iron status.

BACKGROUND: The exact mechanisms by which the effects of inflammation on erythropoiesis occur are still to be determined. We aimed to examine the relation between C-reactive protein (CRP) and erythropoiesis as quantified by the absolute reticulocyte count (RTC) and the possible effect of iron status on this relationship. METHODS: As part of a study that follows the changes of haematologic parameters after the intravenous (IV) administration of iron in 93 stable haemodialysis (HD) patients, we made a cross-sectional analysis of baseline measurements and an analysis of changes in RTC 1 week after baseline measurements and iron administration. RESULTS: Multiple linear regression analysis revealed that RTC had a positive correlation with CRP; RTC had a negative correlation with reticulocyte haemoglobin content (CHr). An interaction was also found between CRP and CHr in that CRP had a significant relation to RTC only in those patients whose CHr was more than 31.2 pg. At lower values of CHr, the correlation between CRP and RTC was not significant. Five days after the IV administration of 200 mg iron sucrose, a significant increase of RTC was observed, only in those patients with elevated baseline CRP levels who also showed an increase in CHr levels from ≤ 31.2 pg at baseline to ≥ 31.2 pg post-administration, supporting the presence of an independent positive correlation between CRP and RTC when iron is adequate. CONCLUSIONS: It is indicated that, in HD patients, elevated CRP values are associated with increased erythroid production only when CHr is quite satisfactory.

Do serum and red blood cell folate levels indicate iron response in hemodialysis patients?

The relationship among iron status, ferritin, and folate levels, and the possible contribution of folate measurement in the prediction of iron response in hemodialysis patients, have not been assessed. In addition to serum ferritin and transferrin saturation (TSAT), serum and red blood cell (RBC) folate levels were evaluated as indices for intravenous iron therapy responsiveness in 60 hemodialysis patients. Patients were classified as iron responders or nonresponders depending on whether they exhibited a rise in hemoglobin above 1 g/dl after administration of 1 g of iron sucrose. An inverse relation between serum ferritin concentration and RBC folate levels was found in iron responders (n=26, r=-0.62, p<0.001) but not in nonresponders (n=34, r=0.07, p=nonsignificant). Only serum and RBC folate levels could predict iron response in patients with ferritin levels above 150 microg/l (n=25), with a sensitivity of 83.3% and a specificity of 94.7%. Our findings suggest that RBC folate concentration is inversely related with ferritin levels in iron-responsive but not in non-responsive hemodialysis patients. Serum and RBC folate concentration seems to predict response to iron administration better than serum ferritin or TSAT in patients with ferritin levels above 150 microg/l; therefore, in these patients, it might be used to guide iron management.