R

Red blood cell count

Also called: RBC; Red Cell Count; Erythrocyte Count

Specimen or type of test:

Blood

Purpose of the test

The red blood cell count may be part of a routine complete blood count, or it may be repeated as a single test when the patient’s health condition includes an abnormal altered red cell count. The red cell count also is used to evaluate anemia and polycythemia.

Basics the nurse needs to know

The maintenance of a normal number of erythrocytes in the blood is dependent on the ability of the bone marrow to replace continuously the erythrocytes that are lost or destroyed. Because of the fragility of the cell membrane, the life span of the RBC is approximately 120 days. The bone marrow must produce approximately 1 million new erythrocytes per second to maintain adequate replacement.

The stimulus for additional production of erythrocytes is cellular oxygen deficiency that triggers the flow of erythropoietin by the kidneys. Erythropoietin stimulates the manufacture of new red blood cells by the bone marrow.

Numerous factors can create an imbalance between erythrocyte production and destruction. With excess production and a normal rate of destruction, the red blood cell count is elevated. With either diminished production or excess destruction of red cells in the blood, their number is decreased.

Variation in normal values

The normal red cell count is higher in men than in women, and it is higher in individuals who live at high altitudes. The normal value is lower in men older than age 65. The red cell count is 5% to 6% lower when the blood is drawn from a recumbent patient than from one in an upright position.

Elevated values

Increases in the red cell count may be a result of hyperactivity of the bone marrow cells or of an increase in erythropoietin from renal disease. Relative polycythemia may also produce an increased red cell count. When this problem is caused by dehydration, there are a normal number of erythrocytes, but they are more concentrated in the diminished fluid volume of the plasma.

Decreased values

Decreases in the red blood cell count can occur from an excessive loss of cells, such as with a hemorrhage. It can also occur because of rapid or accelerated hemolysis of the red blood cells. When the bone marrow tissue is damaged, or when a lack of erythropoietin from renal disease exists, too few red cells are produced, and the blood count is low.

REFERENCE VALUES

Male: 4.6 − 6.0 × 10⁶/μL or SI: 4.6 − 6.0 × 10¹²/L

Female: 4.0 − 5.4 × 10⁶/μL or SI: 4.0 − 5.4 × 10¹²/L

How the test is done

Venipuncture or capillary puncture is used to obtain a sample of blood.

Significance of test results

Elevated values

Polycythemia

Renal tumor

Dehydration

Decreased values

Hemorrhage

Fluid overload

Anemia

Aplastic anemia

Bone marrow depression

Hemolysis of erythrocytes

Sickle cell anemia

Glucose-6-phosphate dehydrogenase deficiency

Leukemia

Hodgkin’s disease

Interfering factors

• Hemolysis

• Coagulation of the specimen

• Multiple blood transfusions

• Hemodilution

NURSING CARE

Nursing measures include care of the venipuncture or capillary puncture site as described in Chapter 2, with the following additional measures.

Pretest

• Plan to obtain the specimen when the patient is calm and rested. Exercise, exertion, and fear all increase the red blood cell count.

During the test

• Ensure that the arm or hand that has an intravenous line or saline lock is not used to obtain the specimen. Intravenous fluid dilutes the blood and falsely decreases the cell count.

Posttest

• When value of the red cell count is lower than normal, the patient is anemic. The nurse also monitors the laboratory results of the hemoglobin and hematocrit because these values will also be lower than normal. In some conditions, such as glucose-6-phosphate dehydrogenase deficiency, sickle cell anemia, or other hemoglobinopathy, the patient must contend with a chronic, life-long anemia problem. In other cases, such as during treatment with chemotherapy or radiation, the effect of bone marrow suppression, or after a hemorrhage, the anemia is a more recent development. Medical intervention depends on the origin of the red blood cell or bone marrow problem.

• With a low red cell count, the nurse assesses for signs of anemia, including pallor, fatigue, dyspnea on exertion, palpitations, and dizziness. The patient’s main problems are activity intolerance and fatigue. The problems occur because there are too few red blood cells to supply sufficient oxygen to the cells. The heart must work harder to increase the circulation and use the red cells that are available.

Red blood cell morphology

Also called: Peripheral Blood Smear; Blood Smear Morphology

Specimen or type of test:

Whole blood

Purpose of the test

The cells of the blood are examined to help identify causes of anemia and to evaluate the function of the bone marrow.

Basics the nurse needs to know

Morphology refers to the shape and structure of cells. Red blood cell morphology is a microscopic or automated analyzer examination of stained red blood cells to identify any altered shapes or structures. In most hematologic diseases, specific characteristic changes can be seen in the blood cells. Changes in the size, structure, and shape of the cells or changes in the number and distribution of the cells may occur, or a combination of these changes may be seen. The microscopic visualization of these changes helps diagnose or confirm the hematologic diagnosis. In addition to red cell morphology, the peripheral smear can be used to examine white blood cell and platelet morphology.

The shape and structure of red blood cells

Normal erythrocytes are circular discs of uniform size, color, shape, and appearance. The red cells should be paler in the center than on the periphery. They are described as normocytic (normal in size) and normochromic (normal in color). The patient can be anemic despite these normal characteristics. A normocytic, normochromic anemia is one that is caused by hemolysis of erythrocytes or severe blood loss. The cells are normal, but too few of them remain in the blood.

Abnormal erythrocytes vary in size, color, hemoglobin content, shape, staining properties, and structure. The altered size is caused by a defect in erythropoiesis. The bone marrow can be adversely affected by genetics, poor nutrition or changes in either bone marrow cells or bone marrow function.

Abnormal color is the result of an alteration in hemoglobin content. Too little hemoglobin results in a pale color of the erythrocytes. The problem may be the result of iron deficiency or abnormal hemoglobin synthesis.

Poikilocytosis refers to abnormally shaped red cells. Abnormal erythrocyte structure includes the presence of a nucleus that identifies these cells as normoblasts, basophilic stippling, Howell-Jolly bodies, or Heinz bodies. The variations of some of the characteristics of erythrocytes, and their relationships to hematologic disease, are presented in Table 14.

Table 14 Characteristics of Erythrocytes: Relationships to Hematologic Diseases

REFERENCE VALUES

Normal cell shape and structure

How the test is done

Venipuncture or capillary puncture is done to obtain the specimen of blood. For the peripheral smear, two slides are prepared immediately using drops of venous or capillary blood.

Significance of test results

See Table 14 for abnormal values.

Interfering factors

• Hemolysis

• Coagulated specimen

NURSING CARE

Nursing measures include care of the venipuncture or capillary puncture site as described in Chapter 2. No other special nursing measures are required.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. K
2. Specimen collection procedures
3. S
4. A

Stay updated, free articles. Join our Telegram channel

Join

Full access? Get Clinical Tree