CLINICAL-SIGNIFICANCE OF RED-BLOOD-CELL DISTRIBUTION WIDTH IN THE ELDERLY - A POTENTIAL INDICATOR OF BONE-MARROW STIMULATION BY ERYTHROPOIETIN

To investigate the clinical significance of red blood cell distributio n width (RDW) and haemoglobin distribution width (HDW) in the elderly and their relationships with erythropoietin (EPO) secretion, we measur ed red cells parameters using a Technicon H1 system and serum EPO usin g a radioimmunoassay in 247 elderly subjects (normal: n = 150; preanae mic iron deficiency: n = 24; iron deficiency anaemia: n = 8; senile an aemia: n = 65). RDW was slightly higher in the elderly subjects with p reanaemic iron deficiency (14.1 +/- 1.1 %) than in the normal elderly subjects (13.5 +/- 0.7%). It was highest in iron deficiency anaemia (1 6.1 +/- 1.3%), while the increase in senile anaemia was limited (13.9 +/- 1.2%). The HDW increased only in iron deficiency anaemia. There wa s a strong positive relationship between EPO and RDW in iron deficienc y anaemia (r = 0.817, P < 0.01). Moreover, this correlation was also f ound in preanaemic iron deficiency (r = 0.456, P < 0.05), but not in s enile anaemia, suggesting that bone marrow hypoactivity may partly pla y a role in the pathogenesis of senile anaemia. All the eight subjects with iron deficiency anaemia had a RDW greater-than-or-equal-to 14.9% (mean + 2 SD of normal subjects), while 55 (85%) of the 65 with senil e anaemia had a RDW < 14.9%. Both the RDW and EPO levels of six anaemi c subjects with high RDW values (greater-than-or-equal-to 14.9%) after oral iron therapy for 56-78 days decreased significantly. Our results suggest that RDW is useful to distinguish iron deficiency anaemia fro m senile anaemia, and may be a potential parameter of bone marrow stim ulation by EPO.