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Reticulocyte Information and Courses from MediaLab, Inc.

These are the MediaLab courses that cover Reticulocyte and links to relevant pages within the course.

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Alpha Thalassemia
Alpha Thalassemia Major

In alpha thalassemia major, anemia is actually fatal. Red blood cell (RBC) count is increased while hemoglobin is severely decreased. Both the MCV and MCHC are decreased. Red cell distribution width (RDW) is increased. RBC morphology shows slight hypochromic microcytosis with codocytes, schizocytes, nucleated RBCs. Reticulocytes are increased.Hemoglobin electrophoresis demonstrates abnormal pattern on cord blood: Hb A - absentHb Bart's - 80-90%Hb Portland - 0-20%Note: Bone marrow demonstrates marked erythroid hyperplasia.

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Alpha Thalassemia Intermedia

In alpha thalassemia intermedia, anemia is moderate with a decreased hemoglobin and red blood cell count. The MCV and MCHC are decreased. The RDW is increased due to red blood cell anisocytosis and poikilocytosis. RBC morphology shows slight hypochromic microcytosis with codocytes (target cells), schizocytes, and basophilic stippling. Reticulocytes are moderately increased.Hemoglobin electrophoresis demonstrates abnormal patterns in both adults and neonates.Adults:HbA - decreasedHbA2 - decreasedHbF - normal to decreasedHb H - 2-40% (beta chain tetramers)Noe: Neonates: 10-40% Bart's (gamma chain tetramers), Hb H inclusions are frequently seen. Bone marrow demonstrates erythroid hyperplasia.

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Alpha Thalassemia Minor

In alpha thalassemia minor, anemia is mild to absent. The red blood cell count is increased, while the hemoglobin is slightly decreased. The MCV and MCHC are slightly decreased. The RDW is normal to slightly increased. Red blood cell morphology shows slight hypochromic microcytosis. Reticulocytes are normal to slightly increased.Hemoglobin electrophoresis demonstrates a normal pattern in adults:Hb A - 95-98%Hb A2 - 1.5-3.7% Hb F - <2%Note: Neonates have 5-15% Bart's Hemoglobin (gamma chain tetramers). Hb H inclusions are rarely seen. Bone marrow demonstrates erythroid hyperplasia.

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Silent Carrier

In silent carrier alpha thalassemia, anemia is absent. The red blood cell count is within normal limits. Hemoglobin is also within normal limits. The MCHC (mean corpuscular hemoglobin concentration) and MCV (mean cell volume) are normal to slightly decreased. The RDW (red cell distribution width) is within normal limits. Red blood cell morphology and reticulocyte percentatge are normal.Hemoglobin electrophoresis demonstrates a normal adult pattern:Hb A - 95-98%Hb A2 - 1.5-3.7% Hb F - <2%Note: Neonates have 1-2% Bart's Hemoglobin (gamma chain tetramers). Hb H inclusions are rarely seen. Bone marrow is also normal.

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Reticulocytes

Upon analysis using Brilliant Cresyl Blue stain, RNA present in reticulocytes will appear as darker inclusions, similar to how they appear with New Methylene Blue stain. These RNA inclusions are fewer in number than Hemoglobin H bodies, and are only seen in reticulocytes.

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Match the images of these cells stained with the supravital stain, brilliant cresyl blue, with the appropriate description.View Page

Authentic and Spurious Causes of Thrombocytopenia
Laboratory Findings

These laboratory findings are associated with TTP and HUS:Thrombocytopenia -- Platelet count is often less than 20 x 109/L in TTP, but may not be as low in HUS. Schistocytes (red blood cell fragments, as indicated by the arrows in the image to the right) may be observed on the peripheral blood smear. Schistocytes are the result of erythrocytic membrane damage caused by sheering of red blood cells as they pass through a fibrin mesh of clot formation occurring in the blood vessels. LDH, serum bilirubin, and reticulocyte counts are elevated. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are usually normal. Proteinuria and hematuria may be present.

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Beta Thalassemia
Hematologic Findings For Various Types of Beta Thalassemia

Beta Thalassemia MinimaBeta Thalassemia MinorBeta Thalassemia Intermedia Beta Thalassemia MajorDelta-Beta ThalassemiaAnemiaAbsentMild to absentModerateSevereMildRed blood cell (RBC) countNormalIncreasedDecreased to normalDecreasedDecreased to normalHemoglobin(Hb)NormalDecreased 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 decreaseMarked decreaseMarked decreaseMarked decreaseMay be slightly decreasedMean corpuscular hemoglobin concentration (MCHC)Slight to no decreaseMarked decrease Marked decreaseMarked decreaseMay be slightly decreasedRed blood cell distribution width (RDW)NormalNormal to slightly increasedIncreasedIncreasedNormalRBC morphologyNormalMarked hypochromia and microcytosis Codocytes (target cells) Possible basophilic stippling Nucleated RBCs are usually not presentMarked hypochromia and microcytosis Codocytes (target cells) Possible basophilic stippling Nucleated RBCs are usually not presentMarked hypochromia and microcytosis Codocytes (target cells) schistocytes ovalocytes basophilic stippling polychromasia nucleated RBCs Possible hypochromia and microcytosis Codocytes (target cells) Basophilic stippling Reticulocyte countNormalMay be slightly increasedSlightly increased (<5%)Mildly increased (5 - 10%)Mildly increasedHb electrophoresisNormal patternDecreased 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.

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Erythrocyte Inclusions
Reticulocytes

Although the nucleus has been extruded, the reticulocyte is still considered immature because it retains numerous organelles needed for hemoglobin production, such as ribosomes, mitochondria, and fragments of the Golgi apparatus. A reticulocyte normally remains in the bone marrow for one or two days before entering the circulation and its final 24 hours of maturation. The red cell is mature when hemoglobin production is complete and the organelles have disintegrated. The reticulocyte is slightly larger (10 microns) than the mature erythrocyte. Reticulocytes appear blue-gray on the Wright or Wright-Giemsa-stained smear and are referred to as polychromatophilic red cells (indicated by the arrow in Image A). The residual RNA in the cytoplasm causes the blue-gray color. A supravital stain, such as new methylene blue N or brilliant cresyl blue, is used to stain reticulocytes (indicated by the arrows in Image B) for an actual count.Automated methods are available for performing reticulocyte counts. An automated method provides a more accurate absolute retiulocyte count than the manual method that is reported as a percentage of total RBCs.

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Which of the following statements characterize a reticulocyte?View Page
Which of the following statements best describes the appearance of Cabot rings?View Page

Erythrocyte Inclusions (retired 7/10/2012)
Reticulocytes

Although the nucleus has been extruded, the reticulocyte is still considered immature because it retains numerous organelles needed for hemoglobin production, such as ribosomes, mitochondria, and fragments of the Golgi apparatus. A reticulocyte normally remains in the bone marrow for one or two days before entering the circulation and its final 24 hours of maturation. The red cell is mature when hemoglobin production is complete and the organelles have disintegrated. The reticulocyte is slightly larger (10 microns) than the mature erythrocyte. Reticulocytes appear blue-gray on the Wright-Giemsa-stained smear and are referred to as polychromatophic red cells (image on the left). The residual RNA in the cytoplasm causes the blue-gray color. A supravital stain such as new methylene blue N or brilliant cresyl blue is used to stain reticulocytes for an actual count as seen in the image on the right.

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More on Reticulocytes

The number and sizes of the reticulocytes seen on a Wright-Giemsa-stained smear give valuable information regarding the effectiveness or ineffectiveness of erythrocyte production.

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Stress Reticulocytes

When the large reticulocytes normally found in the bone marrow are present in the peripheral blood, they are referred to as shift or stress reticulocytes. These cells may be up to twice the size of normal mature red cells and are an indication of the bone marrow's response to severe anemia. In addition to recognizing their appearance as polychromatophlic cells on Wright's stained smears, it is now possible to quantify stress reticulocytes using a fluorescent stain. They are classified as high, medium, or low using a fluorescent-sensitive flow cytometer.

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Which of the following statements characterize a reticulocyte? (Choose ALL of the correct answers)View Page
On a Wright's-stained smear, the blue/gray appearing non-nucleated red cells are called:View Page
Another Stress Reticulocyte

The very large cell in the center of this slide is another example of a stress reticulocyte.

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Erythrocyte Production

Erythrocyte production (including reticulocytes) is increased when the tissues are not receiving sufficient oxygen and the bone marrow is able to respond in a positive manner.Erythrocyte production (including reticulocytes) is decreased when the bone marrow is unable to respond to the signal for increasing production.

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The presence of shift reticulocytes is an indication that red cells are leaving the marrow earlier than normal.View Page
Stress Reticulocyte

The large red cell in the center of this image is an example of a "shift" or stress reticulocyte. This cell has entered the circulation earlier than normal.

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What is Basophilic Stippling?

On a Wright's-stained smear, the presence of multiple dark blue particles or granules of varying size, scattered throughout the cytoplasm of erythrocytes in the reticulocyte stage is called basophilic stippling. There are two types of stippling, fine or diffuse, and coarse or punctate. The erythrocyte containing them may stain normally in other respects or it may be polychromatophilic.

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More on Basophilic Stippling

These dark blue or blue-purple particles are predominantly ribosomes (RNA), normally present in reticulocytes, which have aggregated. It is thought that basophilic stippling is not present in living cells but rather is produced during the smear preparation or staining process.

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Which of the following statements best describes the appearance of Cabot rings?View Page
What are Erythrocyte Inclusions?

Erythrocyte inclusions are elements that may be present in red blood cells (RBCs). The appearance, composition, and associated physiology of the inclusions are specific for each type of inclusion. Identification and quantification of these inclusions are important because their presence may indicate diseases or disorders. Some erythrocyte inclusions cannot be visualized on a Wright or Wright-Giemsa stained smear and require the use of a special stain, such as an iron stain or a supravital stain, to confirm their presence in the erythrocyte. The inclusions discussed in this course are:Reticulocytes, which appear on Wright-stained smears as polychromatophilic RBCsBasophilic stippling Howell-Jolly bodies Siderosomes, which appear on Wright-stained smears as Pappenheimer bodies Cabot rings

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General Laboratory Question Bank - Review Mode (no CE)
A smear that is prepared from equal parts of methylene blue and whole blood will be used for:View Page

Hematology / Hemostasis Question Bank - Review Mode (no CE)
The intracellular precipitates seen in the RBCs in this illustration is termed:View Page
Which of the following methods is not used to classify acute leukemia:View Page
Which of the following observations would best explain why a peripheral blood smear is exhibiting polychromasia:View Page
An increase in the osmotic fragility of erythrocytes is indicative of:View Page
The reticulocyte count is used to assess which of the following:View Page
Which is arranged from least mature to most mature:View Page

Hemoglobinopathies: Hemoglobin S Disorders
Hemolytic Crisis

Sickle cell anemia, in addition to being a hemoglobinopathy, is a hemolytic anemia. Hemolysis is both intravascular (about one-third) and extravascular (about two-thirds). Common markers of hemolysis include elevated LDH, bilirubin, and reticulocyte levels.The hemoglobin that is released into the plasma during intravascular hemolysis combines with nitric oxide (NO). The resulting decrease in NO availability contributes to the vaso-occlusive crisis by stimulating vasoconstriction, endothelial adhesiveness, and thrombosis.Hemolytic crisis also involves splenic sequestration, which occurs in an effort to remove damaged red blood cells. This can result in hypovolemia, which may lead to shock, especially in children. Children can also exhibit splenomegaly due to intrasplenic pooling of blood.Adults in hemolytic crisis may experience autosplenectomy. This occurs when the spleen has multiple infarctions, followed by fibrosis, which renders the spleen nonfunctional.

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Hemolytic Disease of the Fetus and Newborn
Symptoms and Laboratory Findings in Severe HDFN Due to Anti-D

Anti-D causes the most severe HDFN. Symptoms and laboratory findings in HDFN due to anti-D typically include:1. Anemia: Cord Hb can be less than 10 g/dL (100 g/L) and as low as 3–5 g/dL (30–50 g/L).2. Jaundice (icterus gravis): Jaundice occurs after delivery, as fetal bilirubin is cleared by the mother during pregnancy. Extravascular fetal red cell destruction by maternal antibody produces high bilirubin levels. The newborn, who is unable to produce adequate amounts of the liver enzyme glucuronyl transferase, is unable to conjugate the bilirubin into its water-soluble, excretable form.3. Kernicterus: If indirect bilirubin levels reach approximately 20 mg/dL (340 mmol/L) the fat soluble unconjugated bilirubin deposits in the fat-rich brain cells causing brain cell damage. Cerebral palsy, deafness, mental retardation, and other serious disorders can result.4. Hydrops fetalis: Gross edema occurs in severely affected infants, and often results in stillbirth or death soon after birth. Liver failure and hypoproteinemia also play a role in this syndrome.5. Enlarged organs, e.g., liver, spleen and heart6. Laboratory findings include a positive direct antiglobulin test (DAT), low hemoglobin (as above), increased reticulocyte count, and increased nucleated red cells.

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Which symptom of HDFN is associated with low levels of glucuronyl transferase?View Page
Fetal Monitoring: Cordocentesis

Cordocentesis, also known as percutaneous umbilical blood sampling or PUBS, can be done after 18 weeks gestation. PUBS is a prenatal procedure in which a fetal blood sample is removed from the umbilical cord. The sample is confirmed to be of fetal origin by a rapid alkaline denaturation test. The fetal blood can then be analyzed using routine diagnostic tests, e.g., blood group, DAT, reticulocyte count, platelet count, hemoglobin/hematocrit, and more.Cordocentesis / PUBS can also be used to deliver intravenous transfusions (IVTs).

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HIV Safety for Florida
HIV is known as a retrovirus because:View Page

Red Cell Disorders: Peripheral Blood Clues to Nonneoplastic Conditions
A blood smear represented by the photograph was submitted for hematologic review. Based on the erythrocyte morphology and the accompanying histogram, which of the following choices is the most likely situation or condition?View Page
A known case of hemolytic disease of the newborn (HDN) is presented in the image on the right. Many different cellular morophologies are present. Apart from the obvious anisocytosis (microcytes and macrocytes), which additional red blood cell morphologies are worth reporting?View Page
Dimorphic (Double Cell) Population

Dimorphic is a term used to describe two circulating red cell populations. One is the patient's basic red cell population while the other is a second population with distinct morphological features. The distinct populations can be observed in the top image on the right. The bottom image on the right illustrates the two distinct peaks that are observed on the RBC histogram from the automated hematology analyzer.Dimorphic red blood cell populations can be found in conditions/situations such as: red blood cell transfusions, myelodysplasia, refractory anemia with ringed sideroblasts, hemolytic processes involving a reticulocyte response, and when patients are given erythropoietin therapy.It is important to recognize when a population of cells in the peripheral smear is not in context with anticipated laboratory findings and the clinical situation.

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Red Cell Morphology
Which of the following statements is true of polychromatophilic cells?View Page
Color of Erythrocytes

The staining characteristics of an RBC reflect the hemoglobin concentration in the cell as well as the maturity of the cell. RBCs with normal hemoglobin concentration and normal staining characteristics are described as normochromic. Slightly immature, non-nucleated red cells (reticulocyte stage) appear blue/gray on Wright-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 macrocytes by this distinctive color.

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Polychromasia

The cells that are indicated by the arrows in this slide are slightly blue-gray and are examples of polychromatophilic red cells. Increased numbers of these cells (averaging 2 or more per oil immersion field) indicate increased red cell output by the bone marrow. Polychromatophilic cells are larger and younger than mature red cells, and may be larger than 9 µm in diameter. Under normal conditions, these young red cells remain in the bone marrow one or two days before release into the bloodstream. However, when the bone marrow is stressed due to blood loss or other conditions, these cells are prematurely released into the blood, resulting in a blood smear with polychromasia. If stained with a supravital stain, they would be identified as reticulocytes.

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White Cell and Platelet Disorders: Peripheral Blood Clues to Nonneoplastic Conditions
A most useful follow-up test to consider when faced with hypersegmented neutrophils and oval macrocytes (see image) in a peripheral blood smear is:View Page


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