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Information ⬇

Red Blood Cell Count, Indices, Morphology, and Inclusions

Synonym/Acronym

RBC.

Rationale

RBC Count: To evaluate the number of circulating red cells in the blood toward diagnosing disease and monitoring therapeutic treatment. RBC Indices: To evaluate cell size, shape, weight, and hemoglobin (Hgb) concentration. Used to diagnose and monitor therapy for conditions such as iron-deficiency anemia. Variations in the number of cells are most often seen in anemias, cancer, and hemorrhage. Morphology and Inclusions: To make a visual evaluation of the red blood cell (RBC) shape and/or size as a confirmation in assisting to diagnose and monitor disease progression.

Patient Preparation

There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings

Method: Automated, computerized, multichannel analyzers; microscopic, manual review of stained blood smear.

RBC Count
AgeConventional Units (106 cells/microL)SI Units (1012 cells/L) (Conventional Units × 1)
Cord blood4.41–6.214.41–6.21
0–1 wk4.71–7.314.71–7.31
2–3 wk4.31–6.514.31–6.51
1–2 mo3.41–5.813.41–5.81
3–6 mo3.11–4.513.11–4.51
7 mo–15 yr3.71–5.213.71–5.21
16–18 yr4.01–5.414.01–5.41
Adult
Male4.51–6.014.51–6.01
Female4.01–5.514.01–5.51
Values are decreased in pregnancy related to the dilutional effects of increased fluid volume and potential nutritional deficiency related to decreased intake, nausea, and/or vomiting. Values are slightly lower in older adults associated with potential nutritional deficiency. Care must be taken when reviewing complete blood count (CBC) values after a blood product transfusion—documentation should clearly reflect the time and date of the last transfusion with respect to the collection time and date of the study.
RBC Indices
AgeMCV (fL)MCH (pg/cell)MCHC (g/dL)RDWCVRDWSD
Cord blood107–11935–3931–3514.9–18.751–66
0–1 wk104–11629–4524–3614.9–18.751–66
2–3 wk95–11726–3826–3414.9–18.751–66
1–2 mo81–12525–3726–3414.9–18.744–55
3–11 mo78–11022–3426–3414.9–18.735–46
1–15 yr74–9424–3230–3411.6–14.835–42
16 yr–adult
Male77–9726–3432–3611.6–14.838–48
Female78–9826–3432–3611.6–14.838–48
Older adult
Male79–10327–3532–3611.6–14.838–48
Female78–10227–3532–3611.6–14.838–48

MCV = mean corpuscular volume; MCH = mean corpuscular hemoglobin; MCHC = mean corpuscular hemoglobin concentration; RDWCV = coefficient of variation in red blood cell distribution width; RDWSD = standard deviation in RBC distribution width.

RBC Morphology and Inclusions
RBC MorphologyWithin Normal Limits1+2+3+4+
Size
Anisocytosis0–55–1010–2020–50Greater than 50
Macrocytes0–55–1010–2020–50Greater than 50
Microcytes0–55–1010–2020–50Greater than 50
Shape
Poikilocytes0–23–1010–2020–50Greater than 50
Burr cells0–23–1010–2020–50Greater than 50
AcanthocytesLess than 12–55–1010–20Greater than 20
SchistocytesLess than 12–55–1010–20Greater than 20
Dacryocytes (teardrop cells)0–22–55–1010–20Greater than 20
Codocytes (target cells)0–22–1010–2020–50Greater than 50
Spherocytes0–22–1010–2020–50Greater than 50
Ovalocytes0–22–1010–2020–50Greater than 50
Stomatocytes0–22–1010–2020–50Greater than 50
Drepanocytes (sickle cells)AbsentReported as present or absent
Helmet cellsAbsentReported as present or absent
AgglutinationAbsentReported as present or absent
RouleauxAbsentReported as present or absent
Hgb Content
Hypochromia0–23–1010–5050–75Greater than 75
Polychromasia
AdultLess than 12–55–1010–20Greater than 20
Newborn1–67–1515–2020–50Greater than 50
Inclusions
Cabot ringsAbsentReported as present or absent
Basophilic stippling0–11–55–1010–20Greater than 20
Howell-Jolly bodiesAbsent1–23–55–10Greater than 10
Heinz bodiesAbsentReported as present or absent
Hgb C crystalsAbsentReported as present or absent
Pappenheimer bodiesAbsentReported as present or absent
Intracellular parasites (e.g., Plasmodium, Babesia, Trypanosoma)AbsentReported as present or absent

Critical Findings and Potential Interventions ⬆ ⬇

The presence of abnormal cells, other morphological characteristics, or cellular inclusions may signify a potentially life-threatening or serious health condition and should be investigated. Examples are the presence of sickle cells, moderate numbers of spherocytes, marked schistocytosis, oval macrocytes, basophilic stippling, nucleated RBCs (if the patient is not an infant), or malarial or other parasitic organisms.

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

Consideration may be given to verifying the critical findings before action is taken. Policies vary among facilities and may include requesting immediate recollection and retesting by the laboratory or retesting using a rapid point-of-care instrument at the bedside, if available.

Low RBC count leads to anemia.

High RBC count leads to polycythemia.

Overview ⬆ ⬇

Study type: Blood collected in a lavender-top [EDTA] tube or Wright-stained, thin-film peripheral blood smear; related body system: Circulatory/Hematopoietic system. The laboratory should be consulted as to the necessity of thick-film smears for the evaluation of malarial inclusions. The specimen should be mixed gently by inverting the tube 10 times. The specimen should be analyzed within 6 hr when stored at room temperature or within 24 hr if stored at refrigerated temperature. If it is anticipated the specimen will not be analyzed within 4 to 6 hr, two blood smears should be made immediately after the venipuncture and submitted with the blood sample. Smears made from specimens older than 6 hr will contain an unacceptable number of misleading artifactual abnormalities of the RBCs, such as echinocytes and spherocytes, as well as necrobiotic white blood cells.

RBC Count

The RBC count is a component of the CBC. It determines the number of RBCs per cubic millimeter of whole blood. The main role of RBCs, which contain the pigmented protein Hgb, is the transport and exchange of oxygen to the tissues. Some carbon dioxide is returned from the tissues to the lungs by RBCs. RBC production in healthy adults takes place in the bone marrow of the vertebrae, pelvis, ribs, sternum, skull, and proximal ends of the femur and humerus. Production of RBCs is regulated by a hormone called erythropoietin, which is produced and secreted by the kidneys. Normal RBC development and function are dependent on adequate levels of vitamin B12, folic acid, vitamin E, and iron. The average life span of normal RBCs is 120 days. Old or damaged RBCs are removed from circulation by the spleen. The liver is responsible for the breakdown of Hgb and other cellular contents released from destroyed RBCs. Polycythemia is a condition resulting from an abnormal increase in Hgb, Hct, and RBC count. Anemia is a condition resulting from an abnormal decrease in Hgb, Hct, and RBC count. Results of the Hgb, Hct, and RBC count should be evaluated simultaneously because the same underlying conditions affect this triad of tests similarly. The RBC count multiplied by three should approximate the Hgb concentration. The Hct should be within three times the Hgb if the RBC population is normal in size and shape. The Hct plus six should approximate the first two figures of the RBC count within three (e.g., Hct is 40%; therefore, 40 + 6 = 46, and the RBC count should be 4.6 or in the range 4.3 to 4.9). (See the study titled “Hemoglobin and Hematocrit.”)

RBC Indices

RBC indices provide information about RBC size and Hgb content. The indices are derived from mathematical relationships between the RBC count, Hgb level, and Hct percentage. RBC indices are frequently used to assist in the classification of anemias. The MCV reflects the average size of circulating RBCs and classifies size as normocytic, microcytic (smaller than normal), and macrocytic (larger than normal). MCV is determined by dividing the Hct by the total RBC. The RDW is a measurement of cell size distribution. Many of the commonly used automated cell counters report the more sophisticated statistical indices, the RDWCV and RDWSD, instead of the RDW. The RDWCV is an indication of variation in cell size over the circulating RBC population. The RDWSD is also an indicator of variation in RBC size, is not affected by the MCV as with the RDWCV index, and is a more accurate measurement of the degree of variation in cell size. Review of peripheral smears is used to corroborate findings from automated instruments. Excessive variations in cell size are graded from 1+ to 4+, with 4+ indicating the most severe degree of anisocytosis, or variation in cell size. MCH, or average amount of Hgb in RBCs, and MCHC, or average amount of Hgb per volume of RBCs, are used to measure Hgb content. Microscopic review of the peripheral smear can also be used to visually confirm automated values. Terms used to describe the Hgb content of RBCs are normochromic, hypochromic, and hyperchromic. The findings are also visually graded from 1+ to 4+. The MCH is determined by dividing the total Hgb by the RBC count. MCHC is determined by dividing total Hgb by Hct. (See the study titled “Hemoglobin and Hematocrit.”)

RBC Morphology and Inclusions

The decision to manually review a peripheral blood smear for abnormalities in RBC shape or size is made on the basis of criteria established by the reporting laboratory. Cues in the results of the CBC will point to specific abnormalities that can be confirmed visually by microscopic review of the sample on a stained blood smear.

Indications ⬆ ⬇

Interfering Factors ⬆ ⬇

Factors That May Alter the Results of the Study

  • Drugs and other substances that may decrease RBC count by causing hemolysis resulting from drug sensitivity or enzyme deficiency include acetaminophen, aminosalicylic acid, amphetamine, anticonvulsants, antipyrine, arsenicals, benzene, busulfan, carbenicillin, cephalothin, chlorate, chloroquine, chlorothiazide, chlorpromazine, colchicine, diphenhydramine, glucosulfone, gold, indomethacin, nalidixic acid, neomycin, nitrofurantoin, penicillin, phenazopyridine, phenothiazine, primaquine, and quinines.
  • Drugs and other substances that may decrease RBC count by causing anemia include miconazole, penicillamine, probenecid, pyrazolone derivatives, pyrimethamine, streptomycin, sulfamethizole, sulfamethoxypyridazine, sulfisoxazole, tolbutamide, and trimethadione.
  • Drugs that may decrease RBC count by causing bone marrow suppression include antineoplastics (floxuridine).
  • Drugs and other substances that may decrease the MCHC include styrene (occupational exposure).
  • Drugs and other substances that may decrease the MCV include nitrofurantoin.
  • Drugs and vitamins that may increase the RBC count include amphotericin B, erythropoietin, glucocorticosteroids, pilocarpine, and vitamin B12.
  • Drugs and other substances that may increase the MCV include colchicine, pentamidine, pyrimethamine, and triamterene.
  • Drugs and other substances that may increase the MCH and MCHC include oral contraceptives (long-term use).
  • Drugs and other substances that may increase Heinz body formation as an initial precursor to significant hemolysis include acetylsalicylic acid, antimalarials, antipyretics, diuretics (nitrofurans), furazolidone, methylene blue, and naphthalene (mothballs).
  • Hemodilution (e.g., excessive administration of IV fluids, normal pregnancy) in the presence of a normal number of RBCs may lead to false decreases in RBC count.
  • Diseases that cause agglutination of RBCs will alter test results. For example, cold agglutinins may falsely increase the mean corpuscular volume and decrease the RBC count. This can be corrected by warming the blood or diluting the sample with warmed saline and repeating the analysis.
  • Excessive exercise, anxiety, pain, and dehydration may cause false elevations in RBC count.
  • RBC counts can vary depending on the patient’s position, decreasing when the patient is recumbent as a result of hemodilution and increasing when the patient rises as a result of hemoconcentration.
  • Venous stasis can falsely elevate RBC counts; therefore, the tourniquet should not be left on the arm for longer than 60 sec.
  • Lipemia will falsely increase the hemoglobin measurement, also affecting the MCV and MCH.

Other Considerations

  • Use of the dietary supplement liver extract is strongly contraindicated in patients with iron-storage disorders such as hemochromatosis because it is rich in heme (the iron-containing pigment in Hgb).
  • Failure to fill the tube sufficiently (i.e., tube less than three-quarters full) may yield inadequate sample volume for automated analyzers and may be a reason for specimen rejection.
  • Hemolyzed or clotted specimens must be rejected for analysis.

Potential Medical Diagnosis: Clinical Significance of Results ⬆ ⬇

Increased In

RBC Count

  • Anxiety or stress (related to physiological response)
  • Bone marrow failure (initial response is stimulation of RBC production)
  • COPD with hypoxia and secondary polycythemia (related to chronic hypoxia that stimulates production of RBCs and a corresponding increase in RBCs)
  • Dehydration with hemoconcentration (related to decrease in total blood volume relative to unchanged RBC count)
  • Erythremic erythrocytosis(related to unchanged total blood volume relative to increase in RBC count)
  • High altitude (related to hypoxia that stimulates production of RBCs)
  • Polycythemia vera (related to abnormal bone marrow response resulting in overproduction of RBCs)

RBC Size, MCV

MCH

MCHC

  • Spherocytosis(artifact in measurement caused by abnormal cell shape)

RDW

  • Anemias with heterogeneous cell size as a result of hemoglobinopathy, hemolytic anemia, anemia following acute blood loss, iron-deficiency anemia, vitamin- and folate-deficiency anemia (related to a mixture of cell sizes as the bone marrow responds to the anemia and/or to a mixture of cell shapes due to cell fragmentation as a result of the disease)

Decreased In

RBC Count

  • Chemotherapy (related to reduced RBC survival)
  • Chronic inflammatory diseases (related to anemia of chronic disease)
  • Chronic kidney disease (related to decreased production of erythropoietin)
  • Hemoglobinopathy (related to reduced RBC survival)
  • Hemolytic anemia (related to reduced RBC survival)
  • Hemorrhage (related to overall decrease in RBC count)
  • Hodgkin disease(evidenced by bone marrow failure that results in decreased RBC production)
  • Leukemia (evidenced by bone marrow failure that results in decreased RBC production)
  • Multiple myeloma(evidenced by bone marrow failure that results in decreased RBC production)
  • Nutritional deficit (related to deficiency of iron or vitamins required for RBC production and/or maturation)
  • Overhydration (related to increase in blood volume relative to unchanged RBC count)
  • Pregnancy (related to anemia; normal dilutional effect)
  • Subacute endocarditis

RBC Size, MCV

MCH

MCHC

  • Iron-deficiency anemia (the amount of Hgb in the RBC is small relative to RBC size)

RBC Shape

Variations in cell shape are the result of hereditary conditions such as elliptocytosis, sickle cell anemia, spherocytosis, thalassemias, or hemoglobinopathies (e.g., hemoglobin C disease). Irregularities in cell shape can also result from acquired conditions, such as physical/mechanical cellular trauma, exposure to chemicals, or reactions to medications.

  • Acquired spherocytosis can result from Heinz body hemolytic anemia, microangiopathic hemolytic anemia, secondary isoimmunohemolytic anemia, and transfusion of old banked blood.
  • Acanthocytes are associated with acquired conditions such as alcohol-associated cirrhosis with hemolytic anemia, disorders of lipid metabolism, hepatitis of newborns, malabsorptive diseases, metastatic liver disease, the postsplenectomy period, and pyruvate kinase deficiency.
  • Burr cells are commonly seen in acquired renal insufficiency, burns, cardiac valve disease, disseminated intravascular coagulation (DIC), hypertension, IV fibrin deposition, metastatic malignancy, normal neonatal period, and uremia.
  • Codocytes are seen in hemoglobinopathies, iron-deficiency anemia, obstructive liver disease, and the postsplenectomy period.
  • Dacryocytes are most commonly associated with metastases to the bone marrow, myelofibrosis, myeloid metaplasia, pernicious anemia, and tuberculosis.
  • Schistocytes are seen in burns, cardiac valve disease, DIC, glomerulonephritis, hemolytic anemia, microangiopathic hemolytic anemia, renal graft rejection, thrombotic thrombocytopenic purpura, uremia, and vasculitis.

RBC Hemoglobin Content

  • RBCs with a normal Hgb level have a clear central pallor and are referred to as normochromic.
  • Cells with low Hgb and lacking in central pallor are referred to as hypochromic. Hypochromia is associated with iron-deficiency anemia, thalassemias, and sideroblastic anemia.
  • Cells with excessive Hgb levels are referred to as hyperchromic even though they technically lack a central pallor. Hyperchromia is usually associated with an elevated mean corpuscular Hgb concentration as well as hemolytic anemias.
  • Cells referred to as polychromic are young erythrocytes that still contain ribonucleic acid (RNA). The RNA is picked up by the Wright stain. Polychromasia is indicative of premature release of RBCs from bone marrow secondary to increased erythropoietin stimulation.

RBC Inclusions

RBC inclusions can result from certain types of anemia, abnormal Hgb precipitation, or parasitic infection.

  • Cabot rings may be seen in megaloblastic and other anemias, lead poisoning, and conditions in which RBCs are destroyed before they are released from bone marrow.
  • Basophilic stippling is seen whenever there is altered Hgb synthesis, as in thalassemias, megaloblastic anemias, substance use disorder (alcohol), and lead or arsenic intoxication.
  • Howell-Jolly bodies are seen in sickle cell anemia, other hemolytic anemias, megaloblastic anemia, congenital absence of the spleen, and the postsplenectomy period.
  • Pappenheimer bodies may be seen in cases of sideroblastic anemia, thalassemias, refractory anemia, dyserythropoietic anemias, hemosiderosis, and hemochromatosis.
  • Heinz bodies are most often seen in the blood of patients who have ingested drugs known to induce the formation of these inclusion bodies. They are also seen in patients with hereditary glucose-6-phosphate dehydrogenase (G6PD) deficiency.
  • Hgb C crystals can often be identified in stained peripheral smears of patients with hereditary hemoglobin C disease.
  • Parasites such as Plasmodium (transmitted by mosquitoes and causing malaria) and Babesia (transmitted by ticks), known to invade human RBCs, can be visualized with Wright stain and other special stains of the peripheral blood.

Nursing Implications, Nursing Process, Clinical Judgement ⬆

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

  • Discuss how this test can assist in assessing for anemia and disorders affecting the appearance, shape, size, and number of circulating RBCs.
  • Explain that a blood sample is needed for the test.

After the Study: Implementation & Evaluation Potential Nursing Actions

Avoiding Complications

  • Care must be taken when reviewing CBC values after a blood product transfusion—documentation should clearly reflect the time and date of the last transfusion with respect to the collection time and date of the study.
  • Transfusion reaction may occur in some patients. Transfusion reaction is a critical finding. (See study titled “Blood Typing, Antibody Screen, and Crossmatch” for information regarding transfusion reactions.)

Treatment Considerations

  • The results of a CBC should be carefully evaluated during transfusion or acute blood loss because the body is not in a state of homeostasis, and values may be misleading.
  • Considerations for draw times after transfusion include the type of product, the amount of product transfused, and the patient’s clinical situation.
  • Generally, specimens collected an hour after transfusion will provide an acceptable reflection of the effects of the transfused product.
  • Measurements taken during a massive transfusion are an exception, providing essential guidance for therapeutic decisions (e.g., selection of blood products) during critical care.

Nutritional Considerations

  • Discuss consuming a variety of foods within the basic food groups, maintain a healthy weight, be physically active, limit salt intake, limit alcohol intake, and avoid the use of tobacco.
  • Iron deficiency is the most common nutrient deficiency in the United States.
  • Nutritional therapy may be indicated for patients with decreased RBC count.
  • Note: Animal liver (e.g. beef, chicken, deer, lamb) is a nutrient-dense food. Micronutrients, with the exception of vitamin D, are not produced by the body; they must be obtained from dietary sources. Liver is a rich source of vitamins and minerals, most notably providing significant amounts of iron, copper, folate, vitamin A, and vitamin B12. Regularly eating large amounts of animal liver can result in vitamin A toxicity and/or damage to the patient’s liver. The general recommendation commonly given by health-care providers to adult patients is to consume no more than one to three and a half ounces (28 to 100 gm) of liver, once a week. Recommended portions depend on age and gender. Patients should also be aware of vitamin and mineral concentrations contained in dietary supplements that are taken regularly.
  • Patients at risk for iron deficiency (e.g., children, pregnant women and women of childbearing age, low-income populations) should be instructed to include foods that are high in iron in their diet, such as meats (especially liver), eggs, grains, green leafy vegetables, and multivitamins with iron.
  • Iron absorption is affected by numerous factors (see study titled “Iron Studies: Iron (Total), Iron-Binding Capacity (Total), Transferrin, and Iron Saturation”).
  • Patients at risk for vitamin B12 or folate deficiency include those with the following conditions: malnourishment (inadequate intake), pregnancy (increased need), infancy, malabsorption syndromes (inadequate absorption/increased metabolic rate), infections, cancer, hyperthyroidism, serious burns, excessive blood loss, and gastrointestinal damage.
  • Instruct the patient with vitamin B12 deficiency, as appropriate, in the use of vitamin supplements.
  • Explain that the best dietary sources of vitamin B12 are meats, milk, cheese, eggs, and fortified soy milk products.
  • Discuss with the folate-deficient patient (especially pregnant women) the importance of eating foods rich in folate, such as meats (especially liver), salmon, eggs, beets, asparagus, green leafy vegetables such as spinach, cabbage, oranges, broccoli, sweet potatoes, kidney beans, and whole wheat.
  • A diet deficient in vitamin E puts the patient at risk for increased RBC destruction, which could lead to anemia.
  • Nutritional therapy may be indicated for vitamin E–deficient patients.
  • Discuss with the vitamin E–deficient patient that the main dietary sources of vitamin E are vegetable oils (including olive oil), whole grains, wheat germ, nuts, milk, eggs, meats, fish, and green leafy vegetables.
  • Vitamin E is fairly stable at most cooking temperatures (except frying) and when exposed to acidic foods.
  • Supplemental vitamin E may also be taken, but the danger of toxicity should be explained to the patient.
  • Overuse of vitamin E is associated with unexplained bleeding evidenced by bruising or bleeding gums. Vitamin E is heat stable but is very negatively affected by light.

Clinical Judgement

  • Consider ways to emphasize the value to dietary therapy to treat identified nutritional deficiencies.

Follow-Up and Desired Outcomes

  • Acknowledges contact information provided for the U.S. Department of Agriculture’s resource for nutrition (www.choosemyplate.gov).