Causes of microcytic anaemia and evaluation of conventional laboratory parameters in the differentiation of erythrocytic microcytosis in blood donors candidates.

CONTEXT AND OBJECTIVE: Microcytic anaemia results from defective synthesis of haemoglobin in the erythroid precursors, causing a reduction in its mean corpuscular volume (MCV). The most common causes of microcytosis, without the increase in HbA2 levels, are iron deficiency anaemia (IDA) and α-thalassemia. The aim of this study was to identify the causes of microcytic anaemia and evaluate the haematological parameters from blood donors deemed ineligible (due to the low haematocrit level) that would differentiate the IDA and α-thal, whether isolated or in association. METHODS: Genomic DNA was submitted to the polymerase chain reaction multiplex for the diagnosis of the most common allele deletions of α-thal and erythrogram and in order to verify haematological parameters. Iron deficiency (ID) was determined through the measurement of serum ferritin. RESULTS: Of the 204 samples, 82 (40.2%) were identified with ID, 24 (17.8%) with α-thal and 10 (4.9%) with ID associated with α-thal. In the α-thal with ID group haemoglobin (Hb), MCV, mean corpuscular Hb concentration (MCHC) and mean corpuscular Hb (MCH) values were significantly lower compared to the isolated α-thal. In the group with ID Hb, MCV, MCHC and MCH values were significantly lower compared to those with isolated α-thal. The α-thal with ID group, showed Hb, MCV, MCHC and MCH significantly reduced when compared to those with IDA. CONCLUSIONS: This study showed that the values of haematological parameters, especially haematocrit, Hb, MCV, MCH, MCHC and red blood cell distribution width (RDW), are lower in patients with IDA, especially when associated with α-thal and therefore it may be useful to discriminate between the different types of microcytic anaemia.

Etiology of anemia of blood donor candidates deferred by hematologic screening

OBJECTIVE: Iron deficiency is the most common cause of anemia and one of the main factors in the clinical deferral of blood donors. This fact prompted the current study that aimed to determine the prevalence and etiology of anemia in blood donor candidates and to evaluate the hematological screening technique used for the exclusion of these donors. METHODS: This was a prospective study that compared two groups (Anemic and Non-anemic). Initially screening for anemia was performed by manually measuring hemoglobin (Bioclin® Kit); the results were subsequently compared with an automated screening method (Coulter T-890). The etiology was investigated by hemoglobin electrophoresis in alkaline and acid pH, Hb A2 dosage and measurement of the ferritin concentration by immunoagglutination. Differences and associations of interest were analyzed using the Yates and McNemar's Chi-square tests and the Fisher, Mann-Whitney, Wilcoxon and Kruskal-Wallis tests. RESULTS: The deferral rate due to anemia was 4.2%; iron deficiency was identified in 37.5% and beta thalassemia in 9.3% of the excluded candidates. There was a significant discrepancy between the two techniques used to measure hemoglobin with 38.1% of initially deferred donors presenting normal hemoglobin levels by the automated method. CONCLUSION: The results show a high rate of blood donors being deferred for anemia and confirm that iron deficiency is the most prevalent cause. The discrepancies found by comparing screening methods suggest that hemoglobin and hematocrit levels should be confirmed before deferring a donor due to anemia; this may increase supplies in blood banks.