Codocyte Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Codocyte and links to relevant pages within the course.
Learn more about laboratory continuing education for medical technologists to earn CE credit for AMT, ASCP, NCA, and state license renewal and recertification. Or get information about laboratory safety and compliance courses that deliver cost-effective OSHA safety training and continuing education to your laboratory's employees.
| Wright's stained peripheral blood smear made from EDTA specimen.What RBC morphologies are present? | View Page |
| Summary The normal RBC count (4.84 x 1012/L) in this case, together with the decreased hemoglobin (8.4 g/dL) and MCV (59 fl) is an indicator of ineffective erythropoeisis that often points to thalassemia.The RBC morphology shows slight hypochromic microcytosis with codocytes, schizocytes, and basophilic stippling. Schizocytes form by several mechanisms, one being the removal of RBC inclusions.This patient's elevated bilirubin correlates with her presentation of sclera icterus; her splenomegaly is consistent with increased RBC destruction.The Hb electrophoresis demonstrated a normal pattern, initially, but the unstable Hemoglobin H was revealed upon repeat electrophoresis with reduced incubation time. Hemoglobin H is the result of beta globin chain tetramer formation due to the insufficient supply of alpha globin chains in alpha thalassemia intermedia.People with Hemoglobin H disease (alpha thalassemia intermedia) usually have a normal life expectancy without treatment. However, hemolysis may lead to moderate anemia that may be treated with splenectomy. | View Page |
| Alpha Thalassemia Major Anemia is fatal.Red blood cell (RBC) count is increased.Hemoglobin (Hb) is severely decreased.Mean corpuscular volume (MCV) is decreased. Mean corpuscular hemoglobin concentration (MCHC) is decreased.Red cell distribution width (RDW) is increased.RBC morphology shows slight hypochromic microcytosis with codocytes, schizocytes, nucleated RBCs.Reticulocytes are increased.Hb electrophoresis demonstrates abnormal pattern on cord blood: Hb A - absentHb Bart's - 80-90%Hb Portland - 0-20%Bone marrow demonstrates marked erythroid hyperplasia. | View Page |
| Alpha Thalassemia Intermedia Anemia is moderate.RBC count is increased.Hb is moderately decreased.MCV is decreased. MCHC is decreased.RDW is increased.RBC morphology shows slight hypochromic microcytosis with codocytes, schizocytes, and basophilic stippling.Reticulocytes are moderately increased.Hb electrophoresis demonstrates abnormal patterns in both adults and neonates.Adults:HbA decreasedHbA2 decreasedHbF normal to decreasedHb H -2-40% (beta chain tetramers)Neonates: 10-40% Bart's (gamma chain tetramers)Hb H inclusions are frequently seen.Bone marrow demonstrates erythroid hyperplasia. | View Page |
| Hematologic Findings For Various Types of Beta Thalassemia 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. | View Page |
| Codocytes (target cells) are a typical finding in which of the following types of beta thalassemia? | View Page |
| This is a representative field from the patient's peripheral blood smear.What RBC morphology is prominent on this patient's smear? | View Page |
| Case History Summary The laboratory findings in this case represent classic findings seen in beta thalassemia minor including: erythrocytosis, decreased hemoglobin, normal hematocrit, normal RDW, and the presence of codocytes (target cells). This patient does have a mild anemia, but some patients with beta thalassemia minor have no anemia. Hemoglobin electrophoresis confirms this diagnosis, showing an increased Hb A2 level and decreased Hb A.In addition, the slightly increased iron and slightly decreased TIBC contradict a suspicion of iron deficiency. These chemistry results are typical for beta thalassemia, even though the red blood cells are microcytic and hypochromic. | View Page |
| What is this patient's most likely diagnosis?Review of results:This patient has an increased RBC count with a decreased Hb and normal Hct. The MCV is microcytic and the RDW is within normal limits. Many codocytes are present on the peripheral smear. Serum iron is 165 µg/dL (normal = 60 -150 µg/dL), and the TIBC is 230 µg/dL (normal = 250 - 400 µg/dL). Consider also the findings on alkaline hemoglobin electrophoresis. | View Page |
| The underlying condition where the defective erythrocytes marked by arrows are of diagnostic importance is: | View Page |
| Leptocytes and target cells The peripheral blood smear of HbH disease presented before is reviewed in the upper photograph.As mentioned, these leptocytes are pale-staining with hemoglobin confined to a thin, flat, cell membrane.Illustrated in the lower photograph are target cells or codocytes (a term derived from a Greek word for hat)Membrane accumulations of phospholipids and cholesterol (particularly in obstructive jaundice) promote target cell formation.When these cells are spread out on a glass slide, a central bump of hemoglobin appears to produce the target, a manifestation of excess cellular membrane compared to the amount of hemoglobin inside.The early descriptions of thalassemias, then called hereditary leptocytosis (Mediterranean anemia, Cooley's anemia), include description of leptocyes, which may have represented HbH disease. | View Page |
| What are the cells that are indicated by the arrows in this image? | View Page |
| What is the name of the cells that are indicated by the arrows in this slide? | View Page |
| What are the abnormal red blood cells that are indicated by the arrows in this peripheral blood smear image? | View Page |
| Synonyms for Codocytes Synonyms for a Codocyte include target cell, Mexican hat cell, and Leptocyte(thin). | View Page |
| Match the following terms with their synonyms. | View Page |
| The abnormal form seen in the center of this slide is: | View Page |
| The cells indicated by the arrows in this field are: | View Page |
| What are the cells that are indicated by the arrows in this field? | View Page |
| Codocyte Codocytes are thin-walled cells showing a darkly-stained center area of hemoglobin which has been separated from the peripheral ring of hemoglobin. When viewed under the electron microscope. these cells have a cup-shaped appearance. A codocyte is seen in the center of this slide. | View Page |
| Another Target Cell Another example of a target cell (or codocyte) is seen in the center of this slide. Notice that the hemoglobin in the center of this cell is somewhat lighter in appearance than in the previous slide. A second codocyte can be seen in the upper left portion of the slide. Codocytes appear in conditions which cause the surface of the red cell to increase disproportionately to its volume. This may result from a decrease in hemoglobin, as in iron deficiency anemia, or an increase in cell membrane.
Target cells have excess membrane cholesterol and phospholipid and decreased cellular hemoglobin. Examples of other conditions in which target cells may be present include thalassemias, hgb C disease, post splenectomy and obstructive jaundice. Since their presence can be the result of an in vitro artifact, their value in clinical diagnosis is limited. | View Page |
| The predominant abnormal forms seen in this slide are: | View Page |