Anemias Flashcards
What is anemia?
A blood disorder where there is a deficiency of erythrocytes or hemoglobin.
What are the three basic problems causing anemia?
1) defective erythropoiesis (defective production)
2) excessive hemolysis (premature or abnormal destruction)
3) excessive loss (ex. hemorrhage)
What is the pathophysiology or anemia?
- abnormal RBC number, structure or function
- leads to decreased oxygen carrying capacity
- leads to hypoxia
What are the manifestations of moderate anemia?
- dyspnea
- palpitations
- chronic fatigue
What are the manifestations of severe anemia?
- chronic exhaustion
- palpitations
- profound weakness
- dizziness
- headache
- sensitivity to cold (metabolism makes heat)
How many erythrocytes do we make in a minute?
180 million
Do RBCs transport nutrients?
no, they transport oxygen
What are the components of hemoglobin?
- globin (protein)
- heme (x4)
- iron (x4)
What are the different types of anemia?
- iron deficiency
- vitamin B12 and folic acid deficiency
- pernicious anemia
- aplastic anemia
- hemolytic anemia
- hemorrhagic anemia
- sickle cell anemia
Where does oxygen bind to hemoglobin?
It binds to the iron.
What causes iron deficiency anemia?
inadequate intake of iron or excessive loss of iron, the type of anemia is prevalent in 3rd world countries where there is a lack of meat in the diet
How do you treat iron deficiency anemia?
- treat the underlying cause
- give iron PO for 4-6 months
Why isn’t a CBC the test of choice to detect iron deficiency anemia?
because it tells you about the cells and not their iron content
What role do vitamin B12 and folic acid have in hematopoeisis?
They are required for DNA synthesis and cell division. If there is a deficiency there will be abnormal production of erythrocytes, leukocytes and thrombocytes.
How are vitamin B12 and folic acid deficiency treated?
- give vitamin B12 (250 micrograms)
- give folic acid
What is pernicious anemia?
When the gastric mucosa is damaged and doesn’t produce intrinsic factor and consequently cannot absorb vitamin B12. This impairs RBC production.
How is pernicious anemia treated?
- give a high dose of vitamin B12 PO (1000 micrograms) to ensure passive absorption (no intrinsic factor needed)
- give vitamin B12 IM if there are neurological symptoms
What is aplastic anemia?
Anemia due to a problem in the bone marrow. This affects RBCs, WBCs and thrombocytes.
What causes aplastic anemia?
1/3 is from autoimmunity, radiation, toxic chemicals, 2/3 is idiopathic
How is aplastic anemia treated?
- treat the underlying cause
- may need a transfusion
- if severe, may need a marrow transplant
What is hemolytic anemia?
When there is premature or excessive hemolysis.
What causes hemolytic anemia?
It can be acquired (autoimmunity or from drugs) or genetic (thalassemia).
What is thalassemia?
A group of diseases where there is defective synthesis of hemoglobin. It causes the production of abnormal RBCs and the abnormal cells are destroyed.
What are the manifestations of hemolytic anemia (in addition to hypoxia)?
- jaundice (from increase in bilirubin)
- splenomegaly (from increased workload)
- hepatomegaly (from increased workload)
How is hemolytic anemia treated?
- treat the underlying cause
- give oxygen for the hypoxia
- give a transfusion
- steroids to dampen hemolysis
- monitor kidney function (excessive hemolysis can cause precipitation to accumulate in renal tubule and lead to renal failure)
- if problem lies in spleen, splenectomy
What is hemorrhagic anemia?
Anemia due to rapid or gradual loss of blood (lose both RBCs and Hb).
What can cause hemorrhagic anemia?
- prolonged or heavy menses
- bleeding peptic ulcers (ulcers in stomach and duodenum)
- CA lesions in gastrointestinal tract
- hemorrhoids
How is hemorrhagic anemia treated?
- find and eliminate the cause (can be tricky)
What causes sickle cell anemia?
It is a genetic problem. It is a recessive homozygous trait.
If an individual is heterozygous, they are a carrier and may have mild anemia or not be affected.
What is the pathophysiology of sickle cell anemia?
- mutated gene codes for Hb S instead of Hb A (adult hemoglobin) [difference is only 1 amino acid]
- Hb S crystalizes on dissociation (after offloading its oxygen) at low partial pressure of oxygen (in tissues, for example)
- this causes RBCs to deform and sickle
- leads to chronic hemolysis
- leads to vessel occlusion in the capillaries
- leads to ischemia and infarction
- obstructed capillaries lead to hypoxia and cause more sickling
- blood viscosity is also increased, which impairs circulation… causes further hypoxia and more sickling
What are the manifestations of sickle cell anemia?
- anemia
- pain from ischemia (from thrombosis and infarction)
- jaundice from increased bilirubin (d/t hemolysis)
How is sickle cell anemia treated?
- supportive (analgesics, rest, oxygen, IV fluids and lytes)
- hypertransfusion in those with increased risk (pregnant, sx) = transfusion till blood is 75% donor blood
- hydroxyurea - causes production of fetal hemoglobin which has a higher affinity for oxygen but this drug also has serious SE (risk for leukemia, hepatotoxic)
- marrow/stem cell transplant
