Anemia Flashcards
What is anemia?
Decreased number of RBC or less than normal quantity of hemoglobin (Hgb) in the blood
What is the consequence of a reduced hemoglobin count?
Results in decreased oxygen carrying capacity
What is the process of RBC development called?
Erythropoiesis
Where does erythropoiesis take place in adults?
RBC are formed in the bone marrow in the spine, ribs, sternum, clavicle, pelvic crest, ends of long bones
Where does erythropoiesis occur in children?
Most bone marrow space
What is a significant component of RBC’s that give them oxygen carrying abilities?
Hemoglobin (two main components)
Protein component (2 alpha/ 2 beta chains)
Heme: porphyrin ring + iron
Does hemoglobin always contain 2 alpha and 2 beta chains?
No, in fetuses hemoglobin contains alpha and gamma chains (beta chains replace gamma subunits with beta subunits)
What is the main hormone that promotes the development of RBCs (erthropoiesis)?
Erythropoietin
-Stimulates stem cells to differentiate
- Increase release of reticulocytes from bone marrow
- Induces Hb formation
What is the feedback loop mechanism that controls erythropoeisis?
When tissue oxygen concentration is low, signals are sent to the kidney to increase production and secretion of EPO (a erythropoiesis promoter hormone)
What are some conditions that may cause anemia?
- Nutritional deficiencies
- Acute or chronic diseases
- Drug induced
What are the three main causes of anemia?
- Blood Loss
- Inadequate RBC production
- Excessive RBC destruction
What are some causes for blood loss?
Trauma
Ulcers
Hemorrhoids
Any drugs that can increase any of the above (ex. Warfarin)
What are some reasons for inadequate RBC production?
- Nutritional deficiency (vitamin B12, iron, folic acid)
- Erythroblast deficiency (bone marrow failure, or bone marrow infiltration (tumours or cancers)
- Endocrine deficiencies
- Chronic disease (ex. renal, liver, infection)
What are some reasons for excessive RBC destruction?
Autoimmune
Drugs
Infection
How can anemias be classified by RBC size?
- Microcytic (small cell)
- Normocytic
- Macrocytic (large size)
a. megaloblastic
b. non-megablastic
How can anemias be classified by RBC colour?
- Hypochromic (pale)
- Normochromic (normal colour)
- Hyperchromic (darker)
What is the cause of microcytic anemia?
Primarily a result of Hb synthesis failure or Hb insufficiency
- can be due to issues with “heme” portion or the “globin” portion
What is the cause of normocytic anemia?
RBCs are normal sized, but there is a low number of them
- Decreased production
- Increased destruction or loss of RBCs
What is the cause of megaloblastic macrocytic anemia?
Impaired DNA synthesis due to vitamin B12 and folate deficiencies
Slow maturing nuclei (more immature compared to cytoplasm)
What is the cause of non-megaloblastic anemia?
Not caused by impaired DNA synthesis
ex. liver disease
How quickly can anemia develop?
Can be acute or develop slowly
The signs and symptoms associated with anemia are associated with the degree of RBC reduction and how long patient has had anemia
What is the end result of long-standing anemia?
Decreased oxygen carrying capacity of the blood
Symptoms:
- Fatugue, dizziness, weakness, SOB, tachycardia
- Decreased mental acuity
- Pallor (pale skin), cold extremities
How is anemia diagnosed?
- Medical history
- Physical examination
- Laboratory evaluation
What are some important questions to ask about medical history for anemia?
- Past or current bloodwork if available
- Comorbid conditions
- Occupational, environmental, and social history
- Transfusion
- Family history
- Medications (cytotoxic agents, anti retroviral drugs, folate antagonists, immunosuppressants)