Red cell distribution width (RDW) in the diagnosis of iron deficiency with microcytic hypochromic anemia.

OBJECTIVE: To study the utility of red cell distribution width (RDW) in the diagnosis of iron deficiency among children with microcytic hypochromic anemia. METHODS: 151 children (6 months-12 years) with microcytic (MCV<75 fl) anemia were classified into iron deficient (IDA) and non-iron deficient anemia (non-IDA) on the basis of serum ferritin and total iron binding capacity (TIBC). RDW values were obtained on an automated hematology analyzer. Receiver operator curves (ROC) were constructed and the utility of RDW in diagnosis of iron deficiency was studied. RESULTS: The mean RDW value was 18.37+/-2.22% in IDA group (97 children) compared to 16.55+/-1.51 % in the non-IDA group (54 children) (p<0.0001, unpaired t test). In IDA group, the mean RDW value was 16.60+/-1.78%, 17.95+/-1.91% and 20.55+/-1.32% among mild, moderate and severely anemic children (p<0.0001, ANOVA test). The corresponding values in non-IDA group were 16.03+/-1.25%, 16.76+/-1.20% and 16.77+/-2.68% respectively (p=0.269, ANOVA test). At a cut-off value of 17.4%, as obtained from the ROC curve, the sensitivity and specificity of RDW in diagnosis of IDA were 81.0% and 53.4% and a positive and negative predictive value of 63.0% and 72.2% respectively. CONCLUSION: RDW has a limited specificity for diagnosis of IDA among children with microcytic hypochromic anemia.

PF3 activity in normal subjects and beta-thalassemia trait.

Platelet factor 3 (PF3) is a platelet membrane component that plays an important role in the activation of the coagulation mechanism. Whenever platelet activation occurred, PF3 is released and participates in thrombin formation. Erythrocyte membrane fraction has also some PF3 like activity, and in abnormal erythrocyte membrane disorders, eg thalassemia, some of the membrane fraction accelerates platelet activation by increasing the PF3 activity. Formerly it was difficult to measure the PF3 activity in plasma. Recently a sensitive chromogenic test to determine the PF3 activity, which could detect the changes in PF3 activity with time, was introduced. This study was done to observe the effect of abnormal erythrocyte on platelet activation. The results obtained using the chromogenic method are the following: whole blood taken from normal subjects showed OD 0.11 +/- 0.06 at 0 minutes after blood collection and then increased significantly (p < 0.01) to 0.21 +/- 0.10 after 90 minutes, while the platelet count did not differ significantly (p > 0.05). Those results showed that there were some platelet activation after 90 minutes as seen by the increased PF3 activity, with no significant change in platelet counts. In beta-thalassemic trait subjects the PF3 activity in whole blood at 0 minutes did not differ significantly compared to the normal subjects, but after 90 minutes it was significantly higher (p < 0.01), OD 0.52 +/- 0.35. However the PF3 in platelet rich plasma at 90 minutes did not increase. The platelet count after 90 minutes was significantly decreased (p < 0.01) This result suggest that the increase in PF3 activity was caused by the role of the abnormal erythrocytes.

Interaction between endothelial cells and thalassemic red cells in vitro.

Erythrocytes from 45 patients with thalassemia and/or hemoglobinopathies were studied for their cytoadherence property to the vascular endothelial cells in vitro. In plasma free medium, erythrocytes from patients with beta-thal/Hb E both splenectomized and nonsplenectomized, HbH diseases (alpha-thal 1/alpha-thal 2 and alpha-thal 1/Hb Constant Spring genotypes) and homozygous Hb E subjects bind to endothelial cells at a greater number as compared to the binding cell number of normal erythrocytes (p-value < 0.05 in all types). Addition of autologous platelet-rich plasma or whole blood to the culture system causes further increase in the number of adhering beta-thalassemia red cells. Platelet-rich plasma had more enhancement effect than the whole blood. However, no such enhancement of both platelet-rich plasma and whole blood was demonstrated in the culture of normal or alpha-thalassemia erythrocytes. Increased binding between red cells and endothelial cells may contribute to the greater risk of vascular occlusion in thalassemic patients.