Episode 8- Overview of Hematological Pathology Flashcards
A reduction in one or more of the major RBC measurements: hemoglobin concentration, hematocrit or RBC count is classified as ________
Anemia
Typical signs and symptoms of anemia include:
- Tiredness/fatigue/exercise intolerance
- Fainting
- Shortness of breath
- Pallor
- Tachycardia/ palpitations
- Worsening of angina
Acquired anemias are caused by:
- Specific deficiencies (iron, vit B12, folate)
- Blood loss (acute or chronic)
- Chronic disease (chronic infections or inflammatory diseaes)
- Hemolysis (AIHA)
What is the most common cause of anemia worldwide?
Iron deficient anemia
What are the characteristics of iron deficient anemia?
- Defective hemoglobin synthesis leads to microcytic (decreased MCV) and hypochromic (decreased MCH & MCHC). 2. ‘Pencil cells’ are seen in blood smear due to unbalanced surface membrane 3. Low rate of hemoglobin results in MORE cell division and smaller ‘pale’ cells with lower levels of hemoglobin.
What is characteristic of this blood smear?
Pencil cells, characteristic in iron deficient anemia
What are the 4 common causes of iron deficiency?
- Overt or occult blood loss (Major cause in affluent countries)
- Dietary (vegans and old timers)
- Dcreased Fe absorption (GI tract problems or drugs impairing absorption)
- Increased Fe requirements (pregnancy & growth spurts)
What are the characteristics of Vitamin B12 deficient anemia?
RBCs are macrocytic (elevated MCV). Macrocytic RBCs often called Megaloblasts –> Megaloblastic anemia.
Why is the physiology behind Vitamin B12 deficient anemia?
DNA synthesis cannot occur without B12 or Folate (therefore cannot divide), but RNA synthesis & protein synthesis continue to occur. Accumulation of protein causes fatty RBCs.
Using your well trained eyes, what is characteristic of this blood smear?
Megaloblasts (Macrocytic RBCs)
What are the main causes of Vitamin B12 deficiency?
- Lack of Intrinsic Factor (IF). Due to autoimmune attack of IF itself or against Parietal cells of stomach (site of IF synthesis). This leads to decreased B12 absorption and is called Pernicious Anemia
*If autoimmune attack is against parietal cells also causes chronic atrophic gastritis*
- Dietary: strict vegans are most susceptible
- Total/Partial Gastrectomy & other stomach procedures: on the rise with more peeps getting these surgeries.
What are the characteristics of folate deficient anemia?
The other key player in DNA synthesis is folate. Does not require intrinsic factor to be absorbed. Produces the same clincial signs of a blood smear as B12 (increased MCV)
What are the 4 main causes of folate deficient anemia?
- Poor nutrition: poverty, elderly, alcoholics
- Increased requirements: pregnancy
- Malabsorption: inflamatory diseases of intestines
- Drugs: inhibiting absorption (anti-epileptics & oral contraceptives)
What are the two general features of large blood volume loss?
Increased HR and low BP
What are the characteristics of Anemia due to ACUTE blood loss?
Initial hemoglobin levels are normal for several hours because RBCs and plasma is lost evenly.
Anemia develops once blood volume is restored (extravascular moves intravascular)
MCV is normal and anemia is called Normocytic.
Anemia due to CHRONIC blood loss is often associated with what other anemia?
Iron deficient anemia (especially in developed countries)
Examples: bleeding gastric ulcer or heavy menstrual flow
What are the characteristics of Anemia of Chronic Disease (ACD)?
Anemia is normocytic. Chronic diseases (like renal failure) produce anemia but mechanisms are poorly understood.
Are Hemolytic anemias acquired or inherited?
Can be either acquired or inherited
What are causes of hemolytic anemias?
Destruction of RBCs at a faster than normal rate leading to a reduced lifespan. RBCs can live as little as 20 days.
Increased RBC breakdown leads to increased RBC synthesis. If bone marrow is working well it may offset the hemolysis anemia
What is the cause of Acquired autoimmune hemolytic anemia (AIHA)?
Autoimmune response directed against the RBCs own antigens.
What nature are virtually all hereditary anemias?
Hemolytic
What are the 3 major groups of hereditary anemias?
- Red cell membrane (hereditary spherocytosis & hereditary elliptocytosis)
- Red cell enzymes (G6PD deficiency)
- Hemoglobin molecules (sickle cell disease & thalassemias)
What is the cause of hereditary spherocytosis?
Molecular defects in genes that code for the peripheral proteins:
Spectrin (alpha/beta)
Ankyrin
Protein 4.2
Band 3
Other erythrocyte membrane proteins
What are the diagnostic tests for hereditary spherocytosis?
- Elevated MCHC (reflecting membrane loss & RBC dehydration)
- Elevated RDW