Chapter 23 Disorders of Red Blood Cells

Red blood cell count (RBC)

Measures the total number of red blood cells in blood

Percentage of reticulocytes (normally approximately 1%)

Provides an index of the rate of red cell production

Hemoglobin (grams per 100 mL of blood)

Measures the hemoglobin content of the blood

Hematocrit

Measures the volume of red cell mass in 100 mL of plasma volume

whole blood transfusion therapy

• Cells and plasma

• Volume replacement with significant

blood loss

PRBC transfusion therapy

• RBCs with little plasma, some

platelets and WBCs

• Symptomatic anemia, platelets are not

fully functional, WBCs not functional

platelets transfusion therapy

Bleeding d/t thrombocytopenia

Prevent bleeding

cryoprecipitate transfusion therapy

• Fibrinogen, von Willebrand factor

• Von Willebrand disease, Hemophilia A/B

plasma transfusion therapy

• All coagulation factors

• Bleeding

anemia

• An abnormally low number of circulating red blood cells or level of hemoglobin, or both

• Results in diminished oxygen-carrying capacity

• Not a disease, but an indication of some disease process or alteration in body function

effects of anemia grouped into three categories

• impaired oxygen transport

• reduction in rbc and hemoglobin

• signs/ symptoms

4 primary causes of anemia

• excessive loss of red blood cells from bleeding

• destruction (hemolysis) of RBCs

• defective RBC production

• inadequate RBC production due to bone marrow failure

clinical manifestations

• Oxygen carrying capacity of hemoglobin is reduced-> tissue hypoxia

• Generalized manifestations

• Lab tests are useful in determining severity and cause of anemia

clinical manifestations include

fatigue, weakness, dyspnea

Headache, faintness

Pallor of skin, mucous membranes,

conjunctive, nail beds, jaundice

Tachycardia, low cardiac output,

palpitations, ventricular hypertrophy

Petechia, purpura

mean corpuscular volume (MCV)

reflects the RBC size

• smaller than normal= microcytic

• larger than normal= macrocytic

• normal size= normocytic

mean corpuscular hemoglobin concentration (MCHC)

• Average amount of Hgb in the volume of RBCs

• Reflects the color

• normochromic= normal color

• hypochromic= pale color

acute blood loss anemia

• Clinical and red cell changes depends on rate of hemorrhage and whether

bleeding loss is internal or external-> Circulatory collapse

• Up to 50% RBC mass may be lost without s/s

• RBC may also fall related to hemodilution->↓ Hgb/Hematocrit levels

• If bleeding controlled and sufficient iron stores: RBC will return to normal in 3-5

days

chronic blood loss anemia

leads to iron deficiency anemia (Doesn’t affect blood volume)

• Asymptomatic until Hgb < 8 d/dL (due to compensation)

• GI bleeding, menstrual disorders

• RBCs produced have too little Hgb

• Small, pale

• Microcytic, hypochromic

hemolytic anemia

Characterized by:

• Premature destruction of red cells

• Retention of iron and other products of hemoglobin destruction

• Increase in erythropoiesis

• Shortened lifespan, breakdown occurs within or outside of vascular compartment and can be

classified as intrinsic or extrinsic

• Normocytic, Normochromic

intrinsic

sickle cell disease

extrinsic

drugs, toxins, antibodies, physical trauma

sickle cell disease

• Abnormal substitution of an amino acid in the hemoglobin molecules

• Inherited disorder in which abnormal hemoglobin (hemoglobin S [HbS]) leads to chronic

hemolytic anemia, pain, organ failure

• Disproportionally affects people with African heritage

etiology sickle cell disease

point mutation in the ß chain of the hemoglobin molecule

clinical manifestations

Factors associated with

sickling/vessel occlusion:

• Cold

• Stress

• Physical exertion

• Infection

• Diseases which cause

hypoxia, dehydration,

acidosis

• Acute pain

• Jaundice

• Vaso-occlusive crisis ->

abdomen, chest, joints,

bones

• Sluggish blood flow causes

chronic damage

• Acute Chest Syndrome:

cough, chest pain, dyspnea

• Stroke

iron deficiency anemia etiology

dietary deficiency, loss of iron through bleeding

iron deficiency anemia

• Iron is a component of heme-> deficiency leads to decreased hemoglobin

synthesis -> impaired oxygen delivery

• Anemia results from chronic blood loss-> inadequate iron available for recycling

• Impoverished populations

• Vegetarians

• GI bleeding

• Menstruation

• Pregnant women

clinical manifestations of iron deficiency anemia

• Related to impaired oxygen transport and lack of hemoglobin

• Fatigue, dyspnea, angina, tachycardia

• Pica: craving for substances lacking nutritional value (clay, ice)

• Spoon-shaped deformity of the fingernails

• Glossitis: Smooth tongue

• Angular Cheilitis: Sores in corners of mouth

• Dysphagia

megaloblastic anemia

• Caused by impaired DNA synthesis that results in enlarged red cells (MCV> 100 fL)

• MCHC normal

• Impaired maturation and division

• Develops slowly-> few symptoms until anemia is advanced

vitamin B12 deficiency

• Essential for DNA synthesis and nuclear maturation -> lead to normal red cell

maturation and division

• Predisposes to myelin breakdown-> neurologic symptoms

• Risk factors: proton pump inhibitors, GI disease , gastrectomy or gastric bypass

pathophysiology of vitamin B12 deficiency

bound to intrinsic factor (IF) [protein secreted by gastric parietal cells]

• intrinsic factor complex protects vitamin B12 from digestion by intestinal enzymes -> travels to ileum where binds to membrane receptors on epithelial cells-> separated from IF and transported into circulation

• Red blood cells produced are abnormally large

pernicious anemia

• Caused by failure to produce intrinsic factor

• Immunologically mediated, possibly autoimmune

• Destruction of gastric mucosa-> Chronic atrophic gastritis- loss of parietal cells

• Other causes: gastrectomy, malabsorption syndromes

clinical manifestations of B12 deficiency

• Mild jaundice

• Neurologic changes: paresthesias of the feet/fingers/ loss of vibratory and

position sense, dementia

• Macrocytic, normochromic

folic acid deficiency

• Required for DNA synthesis and red cell maturation

• Produces the same type of megaloblastic red cell changes that occur in Vitamin

B12 deficiency but no neurologic manifestations

• Folic acid readily absorbed from intestine

folic acid deficiency etiology

• Dietary deficiency

• Alcohol suppresses folate absorption (Alcohol abuse)

• Celiac disease

• Certain drugs cause malabsorption

• Macrocytic, normochromic

aplastic anemia

• Disorder of bone marrow stem cells that results in reduction of all three hematopoietic cell lines

“Pancytopenia”

• Red blood cells

• White blood cells

• Platelets

aplastic anemia etiology

• High doses of radiation, chemotherapy

• Infection (hepatitis)

• Drugs

• Autoimmune

clinical manifestations of aplastic anemia

Petechia, ecchymoses, bleeding from nose/mouth

chronic disease anemia

• Complication of chronic infections, inflammation, cancer

• Anemia of Renal Failure

• Kidneys are primary site for erythropoietin: colony stimulating factor that

stimulates stem cells to differentiate into erythrocytes

• Hemolysis/Hemodialysis

• Anemia of critical illness (ICU patients)

polycythemia

• Abnormally high total red blood cell mass

• Increased RBC count, hemoglobin/hematocrit

• Increased blood volume and viscosity-> interferes with cardiac output and blood

flow

polycythemia etiology

dehydration (water deprivation, diuretics), total increase in RBC mass

polycythemia clinical manifestations

HTN, headache, dizziness, decreased cerebral blood flow, venous stasis,

thromboembolism

geriatric considerations

• HCT levels are lower after age 60 d/t decreased production of RBCs-> fatigue

• Chronic illness, infection: attributes to decreased production

• Anemia in elderly is never normal

• Nutrient deficiencies secondary to altered absorption, interference by

medications, malabsorption.