ch. 23: red blood cells & hemoglobin -

normal level of RBCs in adult males

4.7 to 6.1 mil mcL

normal level of RBCs in adult females

4.3 to 5.4 million mcL

what cellular component do mature RBCs not have, to make space for hemoglobin?

a nucleus

how does the biconcave shape improve O2 transport?

• increases surface area, so more O2 can diffuse in and out of cell

• reducing diffusion distance, enabling o2 to move rapidly btwn cell membrane and interior of cell

what does spectrin, a plasma membrane protein, do?

provides mechanical strength & anchors membrane proteins

what does hemoglobin contain?

• 4 protein chains (globin)

• 4 heme groups

what does hemoglobin synthesis require?

• adequate iron for heme production

• transferrin: delivers iron to bonoe marrow for hemoglobin synthesis

• ferritin: body’s major iron storage protein

what is erythropoiesis?

• making EBCs from pluripotent hematopoietic stem cells in the bone marrow

what is the dev sequence of erythropoiesis?

pluripotent stem cell —> erythroblast —> normoblast —> reticulocyte —> mature erythrocyte

what is erythropoietin (EPO)?

• hormone made by kidneys to stim bone marrow to make RBCs

• decrease in oxygen supply (hypoxia) stims kidneys to produce more EPO

erythrocytes life span

appx 120 days

how are old RBCs and iron removed from the blood?

• RBCs removed by phagocytic macrophages in the spleen, liver, bone marrow

• iron removed and recycled, remaining porphyrin ring is converted into bilirubin

what does a RBC count assess?

• total number of RBCs in 1 microliter of blood

• helps assess oxygen carrying capcity

• low RBC count indicates anemia

• high RBC count suggests dehydration or other disorders

what is a reticulocyte percentage?

• rate of RBC production by bone marrow

• reticulocytes are immature red blood cells

• high: bone marrow is working overtime to release immature red blood cells into your bloodstream

• low: your bone marrow is not making or releasing enough immature red blood cells

what is hemoglobin (Hb)?

the protein in RBCs that carries O2

hematocrit (Hct) measures…

percentage of blood made up of RBCs

how does fluid level in the body effect hematocrit?

• increases with dehydration

• decreases with fluid overload

what is mean corpuscular volume (MCV)?

average size of your red blood cells

what is mean corpuscular hemoglobin concentration (MCHC)>

measures hemoglobin concentration in each cell

what is mean cell hemoglobin (MCH)>

measures hemoglobin mass in each cell

what is anemia?

blood lacks RBCs or hemoglobin to carry adequate oxygen to your body's tissues

affects 25% of pop

4 causes of anemia

1. acute or chronic blood loss

2. destruction of RBCs

3. defective RBC production

4. bone marrow failure —> inadequate RBC production

how are anemias classifed?

1. by etiology

   1. hemolytic anemia bc of increased RBC destruction

2. by size of RBC

   1. identified by -cytic terms

3. hemoglobin content

   1. identified by -chromic terms

what is microcytic?

small RBCs

what is normocytic?

normal size RBCs

what is macrocytic?

large RBCs

what is normochromic?

norm hemoglobin amount

what is hypochromic?

low hemoglobin amount

what is hyperchromic?

high hemoglobin amount

pathophys of iron deficiency anemia?

• body doesnt have enough iron to make hemoglobin

• iron stores deplete

• hemoglobin synthesis decreases

• red blood cells become small and pale

• O2 delivery to tissues reduced

characteristics of iron deficiency anemia?

• most common anemia worldwide

• effects people of all ages

  • highest risk:

    • toddles, women of childbearing age, impoverished, older adults on restrictive diets, teenagers eating lots of fast food

common causes of iron deficiency anemia?

1. dietary iron deficiency

   1. poor intake

   2. vegetarian diets without adequate iron sources

   3. malnutrition

2. chronic blood loss

   1. GI bleeding

   2. menorrhagia

3. increased iron requirements

   1. pregnancy

   2. infancy

   3. childhood and adolescence

when does iron deficiency anemia become symptomatic?

hemoglobin (Hgb) 7-8 g/dL

symptoms of iron deficiency anemia?

• fatigue and weakness

• dyspnea

• tachycardia

• pica

• burning mouth

• smooth, sore tongue (glossitis)

• angular stomatitis (dryness in cornes of mouth)

• spoon shaped nails

lab findings of iron deficiency anemia?

• low Hb and Hct

• low serum iron & ferritin (iron stores)

• microcytic, hypochromic RBCs

• anisocytosis

  • RBCs vary in size more than normal

• poikilocytosis

  • 10% or more of your red blood cells have abnormal shapes

management of iron deficiency anemia?

• ID and treat underlying cause of blood loss

• administer Fe supplements

what causes megaloblastic anemias?

• impaired DNA synthesis commonly due to vitamin B12 deficiency or folic acid deficiency

• vitamin B12 & folate are co-enzymes required for nuclear maturation and DNA synthesis

how does megaloblastic anemia affect RBCs?

• large, immature RBCs

• characterized by MCV greater than 100 fL

how is vitamin B12 absorbed?

• B12 binds with intrinsic factor in the stomach, and this complex is absorbed in the terminal ileum

• deficiency occurs when this process is disrupted

functions of vitamin B12?

• DNA synthesis

• normal RBC maturation & division

• NS function

what is pernicious anemia?

specific kind of megaloblastic anemia caused by a vit B12 deficiency

what causes pernicious anemia?

• inability to produce intrinsic factor, so vit B12 is not absorbed by the small intestine

• commonly caused by destruction of stomach’s parietal cells

what conditions increase risk for pernicious anemia?

• genetics

• gastrectomy

• gastric bypass surgey

• ileal resection

• chronic gastritis

• H. pylori

common hematologic manifestations of pernicious anemia?

• moderate to severe anemia

• mild jaundice

• increased MCV

• normal MCHC

common neurologic manifestations of pernicious anemia?

• tingling and numbness (paresthesia) in hands and feet

• loss of vibration and position sense

• difficulty walking

• muscle weakness

• confusion, memory loss

what does folic acid do?

essential for DNA synthesis and RBC maturation

what is folic acid deficiency anemia?

• type of megaloblastic anemia caused by inadequate folic acid (vit B9)

how does folic acid deficiency anemia affect RBCs?

• produced large RBCs (macrocytic anemia)

• increased MCV

• normal MCHC

what populations are at risk for folic acid deficiency anemia?

• alcoholics

• chronic malnourishment

• cancer patients

do neurological symptoms occur with a B9 deficiency?

nope! only in a B12

what is aplastic anemia?

rare, serious bone marrow failure disorder

pathophys of aplastic anemia?

bone marrow fails to produce enough:

• RBCs

• WBCs

• platelets

results in pancytopenia: low counts of all kinds of blood cells at the same time

what causes aplastic anemias?

• most are autoimmune

• some are from chemicals, drugs, or physical agents

• inherited

  • fanconi anemia

    • mutations in genes responsible for repairing damaged DNA

what causes sickle cell disease (SCD)?

• inherited blood disorder

• abnormal form of hemoglobin

• point mutation in beta-globin —> valine replacing glutamic acid in the beta chain

inheritance pattern of SCD?

autosomal recessive

pathogen of SCD?

• deox Hb molecules stick together, forming long, rigid fibers inside of RBCs

• RBCs become rigid, elongated, and sickle-shaped, with less flexibility

• repeated cycles of sickling and reox cause irreversible damage to RBCs

• RBCs then break down prematurely, causing chronic hemolytic anemia

• small BV obstructed, leading to vaso-occlusion, tissue ischemia, severe pain, and organ damage

what are the common signs and symptoms of SCD caused by?

• hemolysis & hyperbilirubinemia

  • sickled cells are destroyed prematurely

  • hemolysis releases hemoglobin, which is converted to bilirubin

  • excess bilirubin causes jaundice

• vaso-occlusive crisis

  • sickled cells block small blood vessels

  • blocked blood flow causes tissue hypoxia, ischemia, severe pain, and organ damage

• acute chest syndrome

  • chest pain, coughing, difficulty breathing

clinical manifestations of sickle cell disease

• stroke

• blindness

• pneumonia, acute chest syndrome

• heart and liver iron overload

• gallstones

• chronic kidney disease

• avascular necrosis of femoral head

• osteomyelitis

• skin ulcers

diagnosis of SCD based on

clinical findings

hemoglobin solubility testing

diagnosis of SCD confirmed by

hemoglobin electrophoresis

SCD treatment

• preventing sickling episodes

  • taking hydroxyurea

• managing symptoms

• treating complications

what is polycythemia?

abnormally high total RBC mass, characterized by

• hematocrit >54% i nmen

• hematocrit >47% in women

clinical significance of hematocrit >50%

may cause cardiac dysfunction vascular obstruction

clinical significance of hematocrit >60%

can result in reduced O2 delivery, increased blood viscosity

what is relative polycythemia?

hemoglobin and hematocrit levels appear high because of a decreased plasma (liquid) volume rather than an overproduction of RBCs

what is absolute polycythemia?

body produces an actual excess of red blood cells, leading to an elevated red cell mass, higher hemoglobin, and increased hematocrit

what does hematocrit measure?

percentage of cells in 100 mL of plasma

characteristics of primary absolute polycythemia

1. primary: polycythemia vera

   1. neoplastic bone marrow disorder

   2. pluripotent stem cells of bone marrow affected

   3. characterized by

      1. increased RBC mass

      2. elevated WBC count

      3. elevated platelet count

characteristics of secondary absolute polycythemia

• high levels of EPO —> increase in total RBC mass

• physiologic response to chronic hypoxia

• unlike primary polycythemia, it is not a bone marrow disorder

what characterizes a vascular complication of polycythemia vera?

• erythema

• warmth

• burning pain of extremities

clinical manifestations of polycythemia?

• headache, dizziness, weakness

• itching

• night sweats

• weight loss

• splenomegaly