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MEDD 412 > Week 23 - Anemia > Flashcards

Week 23 - Anemia Flashcards

1
Q

How do you categorize RBC disorders?

A

Hemoglobin, membrane, enzymes

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2
Q

Discuss the most common RBC membrane disorders.

A

Hereditary spherocytosis
- Mutations in vertical support components of cytoskeleton (ankryin, spectrum)
- Rigid cells that easily lyse
- Highest prevalence in northern Europeans
- Symptom triad = anemia, jaundice, splenomegaly
Diagnosed by blood smear (spherocytes & polychromasia) and flow cytometry
Management = supportive (folic acid to protect spleen) or spleen removal.

Hereditary elliptocytosis

  • Weakness in horizontal interaction of skeletal protein (alpha-spectrin, beta-spectrin)
  • Clinically mild
  • Same management as spherocytosis, but often just observation
  • More common in sub-Saharan africa
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3
Q

Discuss the most common hemoblobinopathies of RBCs

A

Beta Thalassemia
- mutation in B globin resulting in imbalance of alpha-beta pairing. Autosomal recessive
- Result in damage to the RBC membrane, hepatosplenomegaly and bone problems due to marrow growth trying to compensate
- Diagnosed with Hb electrophoresis and liquid chromatography and manage with blood transfusions every month and iron chelation therapy
Sickle Cell
- Single nucleotide mutation (glu for val) causing Hb to polymerize when deoxygenated. Becomes stiff and deformed. Causes ischemic infarct to end organs.
- Prone to infections due to spleen problems. Manage hydration, pain, infections and transfuse, but not too much. Viscosity is key.

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4
Q

Describe the most common RBC enzymopathies.

A

G6PD deficiency
- Need G6PD to make glutathione which is key for protection against oxidative damage
- Diagnosis made with enzyme assay. Need to be careful of fava beans or any other oxidizing drugs. Sex linked inheritance hitting boys more.
Pyruvate Kinase deficiency
- Final rate-controlling step in glycolysis. Leads to ATP depletion, decrease ion pump action, then hemolysis
- Well tolerated, lifelong anemia. Supportive management.

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5
Q

Describe the clinical and pathogenetic approaches to anemia.

A

Clinical - micro, normo, macrocytic

Patho - Loss, inc destruction, dec production

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6
Q

What are some common medications that may precipitate hemolysis in G6PD deficiency?

A

Anti-malarial drugs, analgesics, antibiotics, infections, fave beans, mothballs

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7
Q

What are some cardinal features of G6PD based on history and exam?

A

Typically male, background (west Africa, mediterranean, middle east, SE Asia), family history, precipitating factor, symptoms of hemolysis.

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8
Q

What lab evidence would indicate oxidative stress hemolysis (G6PD)?

A

CBC with normocytic (maybe macro), blood smear will show bite cells, contracted cells, blister cells and polychromasia (reticulocytosis), heinz bodies

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9
Q

What would be involved in a hemolytic workup?

A

inc bilirubin total and unconjugated, inc LDH, dec haptoglobin, inc relic, neg direct anti globulin test

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10
Q

Describe other drug associated types of hemolysis.

A

Drug-induced immune hemolytic anemias
- penicillin, ampicillin, quinidine, rifampicin, methyldopa
- Drug tags RBC, Ab binds, go to spleen and gets nipped, turn into shistocytes
Drug induced TTP-HUS syndromes (MAHA’s)
- despite thrombocytopenia, prothrombotic states cause thrombi to form in vessels, as blood flows through, the RBCs get sheared and eventually lyse.

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11
Q

How does warfarin work and what factors require vitamin K?

A

Warfarin is a vitamin K antagonist. It acts by blocking Vitamin K epoxide reductase, which normally reduces vitamin K back to its active form. Factors 10, 9, 7 and 2 require K to function. Also proteins C & S

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12
Q

How does heparin work?

A

Activates antithrombin which forms complexes with thrombin, 11a, 10a, 9a, and inactivates them.

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13
Q

What are the advantages of the older classes of anticoagulants?

A

Can monitor therapy with lab tests, long term experience, available reversal agents (warfarin - vitamin K, prothrombin complex concentrate, frozen plasma)(heparin - protamine sulphate)

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14
Q

What are some of the new anticoagulants (DOACS)?

A

dabigatran (thrombin inhibitor), rivaroxaban & apixaban (10a inhibitors)

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15
Q

What are the advantages and disadvantages of the DOACS?

A

Adv
- oral, no monitoring required
Disadv
- No true reversal agent (high thrombogenic risk)

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16
Q

How is iron used as a treatment for anemia?

A

Oral or intravenous (only if severe and no GI tolerance), but oral absorption of iron is poor… Better with meat iron.
Get bad side effects including constipation, nausea, and epigastric discomfort
Only helps anemias that are due to Fe deficiency!

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17
Q

How is B12 used as a treatment for anemia?

A

Oral or IM, but route and dose depends on cause of B12 deficiency.
If it’s pernicious anemia, IM dose is standard, but high oral dose can also overcome impaired absorption.

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18
Q

How are folic acid supplements used as a treatment for anemia?

A

Very rare to have a folic acid deficiency, but it is easy to treat. Just a bit given orally.
Important to check for B12 deficiency as well.

19
Q

How can erythropoiesis stimulating agents be used to treat anemia?

A

EPO is made in the kidney, so it’s most important use is in chronic kidney disease.
Can use for low risk myelodysplasia, chemotherapy induced anemia (very select patients)

20
Q

What are the 5 causes of microcytic anemia? Which ones really matter?

A

TAILS!

Thalassemia, Anemia of chronic disease, iron deficiency, lead poisoning, sideroblastic anemia

21
Q

If you have a macrocytic anemia with increased retics, what do you think?

A

EASY! Always hemolytic anemia or bleeding

22
Q

How are macrocytic anemias divided?

A

Megaloblastic (B12 def) or nonmegaloblastic (liver disease, alcohol excess, hypothyroidism)
Tell from the blood smear! (Oval macrocytes and hypersegmented neutrophils)

23
Q

How are nonmegaloblastic anemias categorized?

A

Bone marrow normal
- alcohol excess, liver disease, hypothyroidism
Bone marrow abnormal
- Failure (myelodysplasia), infiltration (acute leukaemia), suppression (meds)

24
Q

Shistocytes + thrombocytopenia = ________

A

MAHA

25
Q

A severe underlying illness is always associated with what type of anemia?

A

DIC

26
Q

What is the role of hepcidin?

A

It negatively regulates iron release from stores in liver, macrophages and enterocytes. The bone marrow signals the liver to adjust hepcidin production based on needs.

27
Q

What is the approach to a hemolytic anemia?

A

Extrinsic vs intrinsic RBC defects

Intrinsic
- membrane, enzyme, hb
Extrinsic
- autoimmune, non-immune (HUS etc.)

28
Q

What are the two indications for RBC transfusion?

A
  • Improved oxygen carrying capacity

- Suppression of abnormal hematopoiesis (don’t think about)

29
Q

What is the best Hb threshold for RBC transfusion?

A
30
Q

What does a group and screen tell you?

A

Group tells you about ABO & D

Screen tells you about IgG Abs (allo-Ab)

31
Q

What is a crossmatch and how is it done?

A

Final compatibility test before transfusion. Can do immediate spin, indirect anti globulin method, or computer assisted (most common)

32
Q

What is the risk of getting the wrong blood transfused?

A

1/14K

33
Q

What if you need blood and you don’t have time do to a group and screen?

A

You can get emergency-release red cells

34
Q

Where is iron stored in the body?

A

Spleen and liver.

35
Q

Why is iron always protein bound?

A

It is is toxic to cells in ferrous form. Donates electron and creates ROS.

36
Q

Describe how iron is absorbed in the gut.

A

Ferric reductase reduces it to Fe2, transported in by DMT1 protein, ferritin snags it, ferroportin transports it across baso membrane

37
Q

What is the role of transferrin?

A

Transports iron in the blood. Snags it from the ferritin stores in storage cells.

38
Q

What is the role of hemosiderin?

A

More long term storage of iron within cells. Liberated more slowly than ferritin.

39
Q

How does hepcidin actually work?

A

Acts like a hormone. Binds to ferroportin and causes it to be internalized and destroyed. Stops iron release.

40
Q

What are the main causes of iron deficiency?

A

Blood loss, diet, malabsorption

41
Q

What does an iron deficient peripheral blood smear show?

A

Hypo chromatic cells (very pale with thin rim of cytoplasm around edge). Also tear drop cells.

42
Q

What is hemochromatosis and how is it caused?

A

iron overload cause by mutation in HFE protein (plays role in iron sensing)

43
Q

What are the two biochemical reactions B12 is involved in and how?

A

Homocysteine to methionine (generates tetrahydrofolate)

Methylmalonyl CoA to succinyl CoA

These are key for DNA synthesis

44
Q

What are some causes of B12 deficiency? Folate deficiency?

A

Nutrition (takes a long time), pernicious anemia, gastrectomy, intestinal disease

Folate just adds increased utilization…

MEDD 412 (6 decks)

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