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USMLE Hematology Leukemmia and Lymphoma > Microcytic Anemia > Flashcards

Microcytic Anemia Flashcards

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USMLE® Step 1 flashcards
1
Q

How can RBC mass be estimated?

A
  • Hemoglobin (Hb)
  • Hematocrit (Hct)
  • RBC count
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2
Q

In trauma patients with severe blood loss what will the Hb and Hct levels be - PRIOR to giving any fluids

A

Normal - as the concentration of Hb and Hct will remain the same

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3
Q

What is microcytic anemia generally due to?

A

Decreased production of hemoglobin

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4
Q

Name types of microcytic anemias

A
  • Iron deficiency anemia
  • Anemia of chronic disease
  • Sideroblastic anemia
  • Thalassemia
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5
Q

Where does iron absorption take place?

A

Duodenum

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6
Q

What cells transport iron into the blood from the gut?

A

Enterocytes via ferroportin

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7
Q

What transports iron and delivers it to liver and bone marrow macrophages for storage?

A

Transferrin

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8
Q

What is stored intracelular iron bound to?

A

Ferritin

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9
Q

What is the ratio of iron to transferrin?

A

For every 3 transferrin molecules one will be bound to an iron

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10
Q

What is the meaurement of iron in the blood?

A

Serum iron

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11
Q

What is the measurement of transferrin molecules in the blood?

A

TIBC - how many transferrin molecules are in the blood

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12
Q

What is the % saturation?

A

% of transferrin molecules bound to iron

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13
Q

What does serum ferritin show us?

A

How much iron is in storage sites

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14
Q

What can breast feeding without any other foods lead to?

A

Iron deficiency

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15
Q

What parasite can cause iron deficiency in elderly patients in the developing world?

A

Hookworm

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16
Q

What is better absorbed Fe2+ or 3+?

A

Fe2+

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17
Q

What are the stages of iron deficiency anemia?

A
  • Storage iron depleted (decreased ferritin, increased TIBC)
  • Serum iron is depleted (decreased saturation)
  • Normocytic, hypochromic anemia
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18
Q

What is Pica?

A

Patients have an urge to chew on objects/dirt
- Associated with iron deficiency anemia
-

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19
Q

What are the key lab findings in iron deficiency anemia?

A
  • Microcytic, hypochromic (less pink) anemia with increased RDW (RBC distribution width)
  • Low ferritin, increased TIBC
  • Decreased serum iron and decreased % saturation
  • Increased FEP
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20
Q

What is the RDW?

A

RBC distribution width

  • Higher if there is a large variation in the size of the RBCs
  • Lower if the RBCs are all roughly the same size
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21
Q

What is FEP?

A

Free ethrythrocyte protoporphyrin
- This will be increased in iron deficiency anemia as protoporphyrin production is normal and they have less iron to bind to therefore increasing the levels of unbound protoporphyrin

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22
Q

What size dhould RBCs be in relation to lymphocytes?

A

RBCs should be same size as lymphocyte nucleus

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23
Q

What is the treatment of iron deficiency anemia?

A

Ferrous sulfate

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24
Q

What is Plummer-Vinson syndrome?

A

Iron deficiency anemia with esophageal web (mucosal protrusion) and atrophic glossitis
- Presents with anemia dysphagia and beefy-red tongue

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25
Q

What is the most common type of anemia amongst hospitilised patients?

A

Anemia of chronic disease

26
Q

How does chronic disease cause iron defiency anemia?

A

Hepcidin sequesters iron in storage sites

  • Limits iron transfer from macrophages to erythroid precursors
  • Suppresses EPO production
27
Q

WHat are the lab findings in anemia of chronic disease?

A
  • Increased Ferritin
  • Decreased TIBC (free transferrin will go down)
  • Decreased serum iron and decreased % saturation
  • Increased FEP
28
Q

What substance can be given to treat those with anemia of chronic disease (especially cancer)?

A

Exogenous EPO

29
Q

What is the rate limiting step in the production of protoporphyrin?

A

Succinyl coA (+Glycine) to δ-Aminolevulinic acid

  • Enzyme: δ-Aminolevulinic acid synthase
  • B6 acts as a cofactor
30
Q

If protoporphyrin is deficient where does iron remain trapped?

A

Mitochondria - creates dark mitochondria which gather around nucleus creating a ring - ringed sideroblasts

31
Q

What are ringed sideroblasts?

A

Found in sideroblastic anemia

  • Iron-laden mitochondria which form a ring around the nucleus of erythroid precursors
  • Seen with Prussian blue stain
32
Q

What stains iron?

A

Prussian-blue stain

33
Q

What are the causes of aquired sideroblastic anemia?

A
  • Alcoholism - mitochondrial poison which damges the production of protporphyrin
  • Lead poisoning - denatures ALAD and ferrocheletase
  • B6 deficiency (ALAS requires this)
34
Q

What drug commonly causes B6 deficiency?

A

Isoniazid

35
Q

What are the labratory findings in sideroblastic anemia?

A
  • Increased ferritin
  • Decreased TIBC
  • Increased serum iron
  • Decreased % saturation
36
Q

What condition shares the same iron related lab results as sideroblastic anemia?

A

Hemochromatosis

37
Q

What is thalassemia?

A

Decreased production of globin chains

38
Q

What does thalassemia protect against?

A

Plasmodium falciparum malaria

39
Q

WHat are the normal types of hemoglobin?

A
  • HbF (alph2 y2)
  • HbA (alph2 Beta2)
  • HbA2 (alph2 delt2)
40
Q

How many alleles are responsible for alpha chain?

A

4 (on chr 16)

41
Q

What kind of genetic mutation causes alpha thalassemia?

A

Deletion

42
Q

If 1 alpha gene is deleted what is the cause to the patient?

A

Asymptomatic

43
Q

What is the effect of 2 deleted alpha genes? (alpha thalassemia)

A

Mild anemia with slightly increased RBC count

44
Q

If 2 alpha genes are deleted what are the different ways this can occur in alpha thalassemia?

A
  • Cis deletion - same chromosome (worse)

- Trans deletion - opposite chromosome

45
Q

Why is cis deletion considered worse?

A

Associated with increased risk of severe thalassemia in offspring

46
Q

What race of people are more likely to be affected by cis alpha thalassemia?

A

Asians

- Trans more likely in africans

47
Q

What are the effects and clinical findings of alpha thalassemia of 3 genes?

A
  • Severe anemia
  • Beta chains form tetramers (HbH) that damage RBCs
  • HbH is seen of electrophoresis
  • Not seen in utero
48
Q

What type of thalassemia is lethal in utero (hydrops fetalis)?
What are some of the signs

A

alpha thalassemia of 4 genes

  • Gamma chains form tetramers (Hb Barts) that damage RBCs
  • Hb Barts is seen on electrophoresis
49
Q

What is hemoglobin Barts?

A

Tetramer of gamma (y) chains

- Seen in alpha thalassemia of 4 genes

50
Q

How many Beta genes are there and where are they found?

A

2 one on each chromosome 11

51
Q

What kind of genetic disorder causes Beta thalassemia?

A

Gene mutations (not deletions)

52
Q

What are the 2 types of mutations in beta-thalassemia?

A
  • B^0 - no production

- B+ - diminished production

53
Q

What is the mildest form of Beta-thalassemia?

A

Beta thalassemia minor

  • B/B+
  • Asymptomatic with increased RBC count
  • Microcytic, hypochromic RBCs and target cells on blood smear
54
Q

What type of hemoglobin is increased in beta thalassemia?

A

HbA2 (alpha2 delta2)

- Increased from 2.5% to 5%

55
Q

What is the most severe form of Beta-thalassemia?

A

B0/B0

56
Q

When does Beta-thalassemia major present?

A

Few months after birth

- HbF (a2y2) provides protection to fetus and neonate

57
Q

What may damage RBCs in Beta-thalassemia major?

A

Alpha tetramers

May cause:

  • Ineffective erythropoesis
  • Extravscular hemolysis
58
Q

What can Beta-thalassemia cause?

A
  • Extravscular hemolysis
  • Ineffective erythropoesis

Massive erythroid hyperplasia

  • Expansion of hematopoeisis into marrow of skull and facial bones
  • Extramedullay hematopoeisis with Hepatosplenomegaly
59
Q

What virus are beta-thalassemia patients at risk of?

A

Parvovirus B19

60
Q

How can Beta-thalassemia patients gwt hemochromatosis?

A

Chronic transfusions

61
Q

WHat may a bood smear of beta-thalassemia show?

A

Microcytic, hypochromic, target cells and nucleated RBCs

62
Q

What will electrophoresis show in Beta-thalassemia?

A

Little or no HbA

- Increased HbA2 and HbF

USMLE Hematology Leukemmia and Lymphoma (14 decks)

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