Clinical significance of red blood cell distribution width in the elderly: a potential indicator of bone marrow stimulation by erythropoietin

Summary  To investigate the clinical significance of red blood cell distribution width (RDW) and haemoglobin distribution width (HDW) in the elderly and their relationships with erythropoietin (EPO) secretion, we measured red cells parameters using a Technicon HI system and serum EPO using a radioimmunoassay in 247 elderly subjects (normal: n= 150; preanaemic iron deficiency: n= 24; iron deficiency anaemia: n= 8; senile anaemia: n= 65). RDW was slightly higher in the elderly subjects with preanaemic iron deficiency (14.1 ± 1.1%) than in the normal elderly subjects (13.5±0.7%). It was highest in iron deficiency anaemia (16.1 ± 1.3%), while the increase in senile anaemia was limited (13.9 ± 1.2%). The HDW increased only in iron deficiency anaemia. There was a strong positive relationship between EPO and RDW in iron deficiency anaemia (r= 0.817, P<0.01). Moreover, this correlation was also found in preanaemic iron deficiency (r= 0.456, P < 0.05), but not in senile anaemia, suggesting that bone marrow hypoactivity may partly play a role in the pathogenesis of senile anaemia. All the eight subjects with iron deficiency anaemia had a RDW ≥ 14.9% (mean + 2SD of normal subjects), while 55 (85%) of the 65 with senile anaemia had a RDW < 14.9%. Both the RDW and EPO levels of six anaemic subjects with high RDW values (≥ 14.9%) after oral iron therapy for 56–78 days decreased significantly. Our results suggest that RDW is useful to distinguish iron deficiency anaemia from senile anaemia, and may be a potential parameter of bone marrow stimulation by EPO.