If the reticulocyte count is low one should suspect bone marrow suppression or plasma volume expansion

(rare). With high reticulocytes one must rule out blood loss; this can be either internal or external. With no evidence of blood loss one should suspect hemolysis. A Coombs test may be performed to rule out immune-mediated hemolysis. Other clues to immune hemolytic anemia include: rouleaux formation of RBC or monocyte ingestion of RBC on the peripheral smear. A quick test for cold agglutinins is to place an Wnt antagonist anticoagulated tube of blood in the refrigerator: clumping of the RBC after 30–60 minutes suggests the presence of a cold agglutinin. If the above tests are non-diagnostic one should consider intrinsic RBC defects (membrane disorders, hemoglobinopathies or enzyme defects) or extrinsic problems (microangiopathies, R428 cost infections, toxins, other). The key to correct diagnosis of the normocytic

hemolytic anemias is careful review of red cell morphology on the peripheral smear. The paleness of microcytic RBC is due to thinness of the cells. The MCHC is the same in microcytic and normal RBC. Differential diagnosis of microcytosis is given in table III. Lead poisoning should be suspected when there is abnormal basophilic stippling of the RBC. More than 95% of patients with lead poisoning have concurrent iron deficiency. Bcl-w Clues in the differential diagnosis between iron deficiency and beta thalassemia trait are given in table IV. In my experience the most helpful of these are: clear or colorless plasma, a high RDW (red cell volume distribution width) and a low iron/iron binding capacity

(Fe/FeBC) in iron deficiency. Importantly, for any given level of anemia, the RBC morphology on a peripheral smear is greater in patients with beta thalassemia trait than in iron deficiency. The Mentzer index (MCV/RBC) may be helpful since patients with thalassemia trait tend to have smaller red cells with more RBC for any degree of anemia. However, the index tends to be less reliable in patients with minimal or severe anemia [3]. Another important differential in microcytic anemia is between iron deficiency and the anemia of chronic disease (Tab. V). A very low MCV favors iron deficiency. However, there may be a large overlap of test values between these two categories of disease. In addition, many patients may have both problems. Recent data suggest that the ratio transferring receptor (TfR)/log ferritin maybe helpful in resolving this problem since the two diagnoses have opposite effects on both the numerator and denominator of this ratio. Nevertheless some patients will have intermediate values and in those cases a therapeutic trial of iron may be helpful. Increased PMN may be due to many causes in addition to infection. The differential diagnosis (Tab.