Factors determining the percentage of hypochromic red blood cells in hemodialysis patients

Background. Determination of the percentage of hypochro- In order to monitor iron requirements during EPO mic red blood cells (RBC; %HYPO) has been advocated as a therapy, sensitive and specific parameters of functional sensitive index of functional iron deficiency during erythropoieiron deficiency are required. Ferritin and transferrin (Tf) tin (EPO) therapy in hemodialyzed patients. Methods. The significance of %HYPO in chronic renal fail- saturation have generally been used to assess iron availure was evaluated in 64 chronically hemodialyzed patients. The ability. The ferritin concentration adequately reflects linear correlation was determined between %HYPO and 13 iron stores when iron metabolism is in equilibrium. Howvariables, including age, sex, weight, C-reactive protein (CRP), ever, the ferritin level varies independently from iron ferritin, transferrin (Tf), Tf saturation, soluble Tf receptor stores in such conditions as vitamin or folate deficiency, (sTfR), serum iron (SI), urea, parathormone, dialysis dose (Kt/V), dose of EPO administered (EPO), and absolute reticu- inflammatory and infectious diseases, and malignancies locyte count. Multiple regression analyses were then performed [7]. Moreover, the recommended target ferritin level in to select the parameters that jointly provide the best prediction hemodialyzed patients is still under discussion and has of %HYPO. been variously estimated as 100 to 300 ng/ml [8, 9]. FiResults. Univariate analysis showed significant correlations nally, functional iron deficiency may exist in the presence between %HYPO and iron parameters (sTfR, Tf saturation, SI, and ferritin, in decreasing order), EPO, reticulocyte count, of adequate, although nonmobilizable, iron stores. Tf and CRP. Multivariate analysis yielded an equation showing saturation is a more sensitive index of iron availability. that the variation of %HYPO is essentially associated with the However, this parameter is strongly disturbed when combined changes in sTfR, CRP, and EPO dosage. great variations in serum iron (SI) concentration occur.