Polychromasia Information and Courses from MediaLab, Inc.

Beta Thalassemia Silent Carrier Beta Thalassemia Minor Beta Thalassemia Intermedia Beta Thalassemia Major Delta-Beta Thalassemia Anemia Absent Mild to absent Moderate Severe Mild Red blood cell (RBC) count Normal Increased Decreased to normal Decreased Decreased to normal Hemoglobin(Hb) Normal Decreased to normal (10 - 12 g/dL) Decreased (7 - 10 g/dL) Marked decrease (<7 g/dL) Decreased to normal (8 - 13 g/dL) Mean corpuscular volume (MCV) Slight to no decrease Marked decrease Marked decrease Marked decrease May be slightly decreased Mean corpuscular hemoglobin concentration (MCHC) Slight to no decrease Marked decrease Marked decrease Marked decrease May be slightly decreased Red blood cell distribution width (RDW) Normal Normal to slightly increased Increased Increased Normal RBC morphology Normal Marked hypochromia and microcytosis Codocytes (target cells) Possible basophilic stippling Nucleated RBCs are usually not present Marked hypochromia and microcytosis Codocytes (target cells) Possible basophilic stippling Nucleated RBCs are usually not present Marked hypochromia and microcytosis Codocytes (target cells) schistocytes ovalocytes basophilic stippling polychromasia nucleated RBCs Possible hypochromia and microcytosis Codocytes (target cells) Basophilic stippling Reticulocyte count Normal May be slightly increased Slightly increased (<5%) Mildly increased (5 - 10%) Mildly increased Hb electrophoresis Normal pattern Decreased amount of Hb A Variable amounts of Hb A2 and Hb F Decreased amount of Hb A Variable amount of Hb A2 Hb F is usually increased Severly decreased amount of Hb A Variable amount of Hb A2 Usually an increased amount of Hb F Decreased amount of Hb A and Hb A2 Increased amount of Hb F (15 - 20%) If red blood cells are normochromic and normocytic, the RBC, Hb, and Hematocrit (HCT) test values follow in three-fold progression (i.e., RBC x 3 = Hb and Hb x 3 = HCT). This is sometimes referred to as "the rule of threes." This rule will usually not apply in cases of beta thalassemia, particularly beta thalassemia minor where the RBCs are not normochromic and are microcytic, and where there is a disproportionate number of RBCs for the amount of hemoglobin that is present.

In a study on the reporting of red blood cell morphology abnormalities conducted in Ontario, Canada (Hookey L, Dexter D, Lee DH, Laboratory Hematology 7:83-88, 2001), fewer than 50% of 33 participants used the same term to describe the quantitative frequency of peripheral blood abnormalities. Seven blood smears, each containing one of several abnormal erythrocytes-- schistocytes, teardrop cells, acanthocytes, and Howell-Jolly bodies--were evaluated by 32 participants. The participants were asked to document their evaluations from a list of quantitative terms. There was a heterogeneity in the use of terms "rare," "slight," "occasional," "few," "mild", "present," "moderate," "many," and "marked." Choices of terms were subjective without points of reference. Guidelines for establishing standardized qualitative estimations of abnormal erythrocytes in the peripheral smear are presented as follows: 1+ = 2 - 4/Oil Immersion Field (OIF) 2+ = 5 - 7/OIF 3+ = 8 - 10/OIF 4+ = >10/OIF. The terms "few," "moderate," "many," and "marked" may be substituted for the 1+ - 4+ grading system, but only when their specific points of reference are universally understood in tandem with the above guidelines. A comment should be triggered if any erythrocyte abnormalities are seen in numbers >3/OIF including, but not limited to, polychromasia, basophilic stippling, nucleated RBC's, and Howell-Jolly bodies. Rouleaux or RBC agglutination are important findings and must be documented.

In addition to the amount of hemoglobin present, the color of the cell must also be considered. Completely mature red cells appear buff-colored, while slightly immature non-nucleated red cells (reticulocyte stage) appear blue/gray on Wright's stained smears due to the presence of residual ribonucleic acid (RNA).The terms used to describe these cells are polychromasia or polychromatophilia. Polychromatophilic cells are frequently larger in size than mature red cells and can be distinguished from both types of macrocytes by this distinctive color.