Unit 12: Intro to Anemia

Anemia definition

a decrease in the competence of blood to supply tissues with oxygen that results in hypoxia

not actual disease - more a state

Diagnostic evaluation of:

signs/symptoms

pt history

physical exam

lab findings

Anemia characteristics of RBC count, hgb, HCT

decreased RBC

decreased hgb

decreased HCT

What happens after acute blood loss?

blood pressure falls → plasma volume expands quickly to maintain BP but RBC’s can’t

Degrees of anemia in hgb for adults and children

mild = 10-12 g/dL hgb

moderate = 7-10 g/dL hgb

severe = < 7 g/dL hgb

What are some states that cause degrees of anemia in hgb to be different? How are they different?

neonates = hgb inherently higher so may seem elevated

pregnant women = lower

residents of high altitudes = higher

smokers = higher bc chronically hypoxic

Signs/Symptoms of anemia

• fatigue

• pallor

• heart palpitations/decreased BP

• shortness of breath (SOB)

• dizziness

• headache on exertion

Degree of signs/symptoms depend on:

• severity of anemia

• duration of anemia

• how body compensates varies

How does duration of anemia affect the degree of signs and symptoms?

someone who has a longer onset of anemia may be less symptomatic bc body slowly adjusting as they become more anemic

How does the body try to get RBC’s to the tissues faster in order to adapt to anemia?

• increase cardiac output

• increase cardiac rate

• increase circulation rate

How does the body divert oxygen in order to adapt to anemia?

diverts from low O2 requiring organs to vital organs

ex. skin and kidneys = low O2 needs, brain and heart = high O2 needs

How does the body increase tissue O2 efficiency in order to adapt to anemia?

increase 2,3 DPG

• more efficient shift of O2 → tissues

• shifts O2 dissociation curve to the RIGHT (releasing more into tissues)

lack of O2 → acidosis → O2 released more readily into tissues

How does the bone marrow respond to anemia in order to compensate?

can increase production 6-8 times normal rate

results in erythroid hyperplasia

Anemia results when:

marrow can’t make enough RBC’s = production

RBC’s destroyed/lost faster than marrow can replace = destruction

What are some other conditions that cause tissue hypoxia and increased RBC production?

• decreased p O2 at high altitudes

• emphysema

• COPD

• heavy smokers

Lab methods to detect anemia

• RBC count

• Hgb

• HCT

• indices

• retic count

• PBS to analyze size, shape, color, inclusions

• bone marrow aspiration

What are the morphologic classifications of anemias? What are they based on?

microcytic-hypochromic anemias

normocytic-normochromic anemias

macrocytic-normochromic anemias

based on size and color of RBC’s - using indices

What are the functional underlying classifications of anemias and what are they based on?

production anemias

destruction anemias

based on RPI

Microcytic-hypochromic anemias

smaller average size and colorized RBC’s

not enough of them to deliver O2 to tissues

Micro-hypo anemia example conditions

• iron deficiency anemia

• thalassemia

• lead poisoning

• hemoglobinopathies

• anemia of chronic disease/inflammation

• sideroblastic anemia

Normocytic-normochromic anemias

normal average size and colorized RBC’s

not enough of them to deliver O2 to tissues

Normo-normo example conditions

• anemia of renal disease

• anemia associated with neoplasms

• marrow failure

• hemolytic anemia

• anemia of chronic disease/inflammation

• anemia of endocrine disease

Macrocytic-normochronic anemias

larger average size and normally colorized RBC’s

not enough of them to deliver O2 to tissues

Macro-normo example conditions

• megaloblastic anemias

  • vitamin B12 deficiency

  • folate deficiency

  • myelodysplastic syndromes

• non-megaloblastic anemias

  • anemia of liver disease

  • alcoholism

  • myelodysplastic syndromes

What are some limitations of morphologic classification of anemias?

based on AVERAGE size and coloration so can oversimplify complex situation w/ more than 1 condition

Production anemias

“true” production anemia = lack of nutrients/raw materials to make RBC’s

utilization anemias = nutrients/raw materials present, but defective usage

Destruction anemias

RBC’s produced normally

decreased survival time

marrow can’t compensate even with increased production

Characteristics of production anemias

• RPI </= 2 (low)

• low hgb, hct, RBC count

• decreased raw materials

• decreased EPO

• diseased marrow

• utilization defects

Decreased raw materials in production anemias

iron, B12, folate

How does iron deficiency lead to production anemia?

no iron → deficient hgb synthesis

less hgb → cells “filled” w/ less → smaller, paler RBC’s (doesn’t pick up stain)

Thalassemias related to iron deficiency production anemia

genetic defect of low hgb production

both production and destruction

How do B12 and folate deficiencies lead to production anemia?

both required for DNA synthesis

either/both decreased can cause:

• large megaloblastic cells

• nucleus more primitive in developmental stage than cytoplasm (asynchrony)

How does decreased EPO lead to production anemia?

chronic renal disease

endocrine issues - hormones effect EPO

How does diseased marrow lead to production anemia?

toxicity to marrow

• chemicals, drugs, radiation

• aplastic anemia = total shutdown

marrow infiltration by cancer or fibrous tissue

• taking up space where RBC’s being made

How do utilization defects lead to production anemia?

ineffective erythropoiesis

ex. inability to incorporate iron into RBC’s

Destruction anemia characteristics

• RPI > 3

• low hgb, hct, RBC count

• decreased RBC lifespan

• marrow responds appropriately but can’t keep up

What chemistry values indicate destruction anemia?

• increased LDH (in RBC’s so lysis will release)

• increased bilirubin (body trying to break down hgb)

• decreased haptoglobin/hemopexin (grabs free hgb)

• increased urobilinogen

• increased hemosiderin in urine

What can cause increased destruction of RBC’s?

• RBC inclusions

• membrane issues with cytoskeleton (can’t maintain Na/K pump)

• defective hgb like hgb S

• decreased/absent globins (thalassemia)

• RBC metabolism disorders

• immune destruction

• mechanical destruction like heart valves