Anemia Part II Flashcards
Anemias due to increased destruction of red blood cells (hemolysis) consistently show what kind of reticulocyte count?
increased
Bone marrow aspirates or biopsies from patients with hemolytic anemias show?
an increase in primitive nucleated red cell precursors such as normoblasts as well as more differentiated forms
Many of the genetic (inherited) diseases which cause hemolytic anemia produce defects in ?
the red blood cell membrane or cytoskeleton
The red cell membrane is associated with the outer cytoskeleton in which (1) dimers combine to form tetramers producing a head (further associating with (2) and a dimeric tail which associates with (3).
- alpha and beta spectrin
- ankyrin, band 4.2 and band 3.1
- band 4.1
Mutations in the red cell membrane can cause the red cells to lose membrane which makes them more (1) instead of their usual (2) shape.
- spherical
2. biconcave disc
Spherical cells increase the (1) and the red cells lose (2)
- MCHC
2. intracellular potassium, glucose, and water.
Spherical cells are less deformable in the splenic cords so they are removed from circulation by the (1)
- spleen
Splenectomy leaves the (1) but solves the (2) problem of hemolytic anemia
- spherocytes
2. shortened red cell life span
The usual red cell life span is 120 days but these patients have life span closer to (1) days. This clinical disorder is known as (2) and can be due to a variety of mutations in genes encoding any of these genes.
- 10-20
2. hereditary spherocytosis
The mutations arose most commonly in northern Europe and most commonly produce an autosomal (1) disorder with a frequency of 1/5000.
hereditary spherocytosis
1. dominant
Individuals with two mutations will usually be (1) because of the tremendous heterogeneity of causative mutations.
- compound heterozygotes
refers to hereditary spherocytosis
Extravascular hemolysis (in spleen and not within the blood) in patients with hereditary spherocytosis can lead to?
elevation of indirect (unconjugated) bilirubin, cholithiasis with calcium bilirubin stones, and increased lactate dehydrogenase (LDH) due to leakage of this enzyme from the damaged red cells.
What test can identify these spherocytes and why?
An osmotic fragility test because they lyse more readily when incubated in hypotonic solutions.
In contrast, glucose 6-phosphate dehydrogenase deficiency is (1) disorder which usually presents with (2) after patients have an (3) problem due to an infection or treatment with certain drugs.
- an X-linked
- intravascular hemolysis
- oxidative
There are both (1) forms due to differing founder mutations and the (2) form is more sensitive to protein misfolding.
- Mediterranean and African-American
2. Mediterranean
G6PD is a major source of (1) which is needed to restore (2) to eliminate (3)
- reduced NADPH
- reduced glutathione
- oxidative products like hydrogen peroxide (H202).
Why is G6PD deficiency generally episodic and self-limiting?
Older red cells tend to be more suspectible to this type of damage so this disease is generally episodic and self-limiting once more new red cells have been produced (they have more glutathione and NADPH).
The oxidative stress can be due to oxygen radicals from (1) (and leukocytes responding to infections), oxidant drugs including (2), and ingestion of (3) which contains oxidant substances.
- infections
- antimalarials, sulfonamides, and nitrofurantoin
- fava beans
The excess oxidants cause the crosslinking of (1) groups in (2) proteins which denature and bind (3) proteins forming precipitates called (4) which can be stained with (5)
- reactive sulfhydryl
- globin
- membrane
- Heinz bodies
- crystal violet
When the splenic cords deform these cells the (1) try to remove these inclusions by taking a “bite” out: so these cells with areas of membrane loss are called bite cells.
- macrophages
refers to G6PD deficiency
Because there is intravascular hemoglobin outside of red cells, (1) binds the intravascular hemoglobin and is usually decreased in the serum relative to normal since it is consumed.
- haptoglobin
refers to G6PD deficiency
Acute hemolysis results in?
hemoglobinemia (hemoglobin outside RBCs in plasma) and hemoglobinuria.
Chronic hemolysis results in?
hemosiderin in the urine
bilirubin stones in the gallbladder
splenomegaly
secondary hemosiderosis in liver
Sickle cell anemia is an autosomal (1) disorder which produces microvascular occlusion due to a genetic defect which makes red cells occlude small blood vessels.
- recessive
The specific mutation within codon 6 of the adult beta globin gene from GAG to GTG produces an amino acid substitution of (1) (encoded by the triplet GTG) for the normal (2) (encoded by the triplet GAG) which results in Hb S or sickle hemoglobin.
- valine
2. glutamic acid
(1) leads to aggregation of needle like fibers which lose (2) and have (3) pH which leads to more sickling of the hemoglobin.
- Deoxygenated HbS
- intracellular potassium and water
- decreased
The continued dehydration leads to an increase in the
(1) of the sickled cells which correlates well with the presence of crises and other disease.
- MCHC
Reduction of the (1) of the sickle hemoglobin seems to decrease vascular obstruction
- MCHC
Compound heterozygotes with (1) also have sickling in small blood vessels but this may be more a consequence of (2) than in the HbSS homozygous disorder.
- HbC and HbS
2. dehydration
The sickled and dehydrated cells generally show (1) which contributes to the microvascular occlusion
- increased adhesion of the red blood cells to vascular endothelium
Vessel occlusion occurs in the (1) at an early age in patients with sickle cell anemia so they often have (2)
- spleen
2. splenic infarcts and damaged spleen with minimal splenic function.
These patients are said to be autosplenectomized and usually have (1) present due to the lack of splenic function.
- Howell-Jolly bodies
sickle cell disease
During vessel occlusion there is sometimes (1) and the free hemoglobin in the circulation can locally bind and decrease (2) leading to (3)
- intravascular hemolysis
- nitrous oxide
- more vasoconstriction and platelet aggregation.
refers to SCD
Heterozygotes with (1) (called sickle cell trait) usually only have crises or problems under what conditions?
- HbA and HbS
2. at high altitudes or in low oxygen environments.
generally only seen in vascular beds with slow transit time
microvacular occlusion
Clinically sickling crises can lead to acute chest syndrome which is a sickling in the (1) which leads to (2), and continued sickling with microvascular occlusion.
- pulmonary vasculature
2. pulmonary infiltrates, hypoxygenation
Manifestations of sickling crises
Acute chest syndrome, strokes, vascular necrosis of the femur, renal infarcts, skin ulcers, and retinopathy
(1) or other encapsulated organisms occurs as a consequence of inflection and autosplenectomy.
- Osteomyelitis with salmonella
(1) occurs as a consequence of the multiple transfusions and hemolysis which can lead to (2)
- Secondary hemosiderosis (iron overload)
2. calcium bilirubin stones and cholecystitis as well.
Bone marrow expansion occurs in uncommon skeletal areas such as the skull where there is intermittent bone resorption and secondary new bone formation which leads to a tower appearance clinically and a “crewcut” like appearance on X-ray.
sickle cell disease
There can also be erythroid hyperplasia in sites of extramedullary hematopoiesis including (1)
- liver, spleen, and lymph nodes.
refers to Sickle cell disease thalassemia
How is sickle anemia identified?
- Sickle cell test - mix blood with metabisulfite which deoxygenates blood leading to sickling
- Hemoglobin electrophoresis
(more quantitative way to determine the percentage of HbA, HbC, HbS based on the differential electrophoresis of these different proteins)
How do you determine if there is a sickling crisis?
No blood test, apart from elevated WBC levels in inflammatory response; therefore, must be judged by clinical findings.
Pathophysiology of thalassemia
mutational problems with globin gene regulation or problems with splicing of pre-mRNA to mRNA which then encodes for protein
The thalassemias tend to have reduced (1) so they are more quantitative defects than qualitative defects in globin.
- mRNA levels and less protein
Beta thalassemia (decreased (1) produces an excess of (2)
- beta globin mRNA
2. alpha globin chains
Thalassemia with truncated non-functional globin proteins are caused by mutations in?
Frameshift mutations which create internal stop codons
Frameshift mutations leads to (1)
- reduced levels of mRNA