A novel method for calculating mean erythrocyte age using erythrocyte creatine

Abstract

Estimating the lifespan of erythrocytes is useful for the differential diagnosis of anemia. However, measuring the lifespan of erythrocytes was very difficult; therefore, it was seldom measured. Erythrocyte creatine (EC) decreases reflecting erythrocyte age. We developed a method to obtain mean erythrocyte age (M_RBC) from EC.We reanalyzed the previously published data from 21 patients with hemolytic anemia, which included EC and the half-life of ⁵¹Cr.M_RBC and log_e EC showed excellent significant linearity (r = -0.9475, p < 0.001), proving that it could be treated as a mono-exponential relationship within the studied range (EC: 1.45 - 11.76 μmol/g Hb). We established an equation to obtain M_RBC (days) from EC (μmol/g Hb): M_RBC = -22.84log_e EC + 65.83.This equation allowed calculation of M_RBC based on EC which has practical applications such as the diagnosis of anemia.

Keywords: average RBC age; creatine; erythrocyte; hemolysis; lifespan.

Figure 1

Relationship between M_RBC and log_e EC. A significant linear relationship was observed. A red closed circle denotes a standard value; M_RBC = 60 days, EC = 1.4μmol/g Hb. A black line denotes a regression line. EC, erythrocyte creatine; M_RBC, mean erythrocyte age.

Figure 2

M_RBC estimated by EC and ⁵¹Cr. EC derived M_RBC showed excellent estimation. An orange dotted line denotes line of identification (y = x). A black line denotes a regression line. EC, erythrocyte creatine; M_RBC, mean erythrocyte age.

Figure 3

Relationship between EC and M_RBC in the groups with severe and mild hemolytic disease. (A) The two groups show differing regression lines on a normal scale. (B) The two groups are unified on a semi-logarithmic scale. The Red circles represent mild group, sky blue the severe group according to Fehr et al. [13]. EC, erythrocyte creatine; M_RBC, mean erythrocyte age.