Microcytic anemias

Question 1

What is microcytosis?

Answer 1

An extra division of RBC progenitor cells which occurs to maintain haemoglobin concentration

Question 2

What is hemoglobin made of?

Answer 2

Heme and globin

Question 3

What is heme made of?

Answer 3

iron and protoporphyrin

Question 4

Causes of microcytic anemias?

Answer 4

Iron deficiency anemia
anemia of chronic disease
sideroblastic anemia
thalassemia

Question 5

stages of iron deficiency

Answer 5

Storage depleted - decreased ferritin, increased TIBC
Serum iron depleted - decreased serum iron, decreased saturation
Normocytic anemia - bone marrow makes fewer but normal-sized RBCs
Microcytic, hypochromic anemia –bone marrow makes smaller and fewer RBCs

Question 6

Clinical features of iron deficiency

Answer 6

Anemia, koilonychia, pica

Question 7

Lab findings in iron deficiency anemia

Answer 7

Decreased ferritin
Decreased serum iron
Decreased saturaiton
Increased TIBC
Increased free erythrocyte protoporphyrin

Question 8

plummer-vinson triad

Answer 8

iron deficiency anemia, esophageal webs, atrophic glossitis

Question 9

Pathophys in anemia of chronic disease

Answer 9

Chonric inflammation leads to production of hepcidin, which sequester iron in storage sites by limiting transfers of iron from macrophages to erythroid precursors and suppresses EPO
This is done to prevent bacteria from accessing iron

Question 10

Lab findings in anemia of chronic disease

Answer 10

increased ferritin, decreased TIBC, decreased serum iron, decreased iron saturation
increased free erythrocyte protoporphyrin

Question 11

protoporphyrin synthesis pathway

Answer 11

succinyl coa –> ALA via ALAS
ALA –> porphobilinogen via ALAD
porphobiliniogen ———> protoporphyrin
Protoporphyrin + Iron –> Heme via ferrochetalase

Question 12

pathophys of sideroblastic anemia

Answer 12

Congenital defect involve ALAS or acquired. Results in protoporphyrin deficiency and buildup of Iron in mitochondria
Mitochondria form a ring around nucleus of erythroid precursors

Question 13

What is the cause of sideroblastic anemia?

Answer 13

Deficiency of protoporphyrin

Question 14

Causes of acquired sideroblastic anaemia

Answer 14

Alcoholism - mitochondrial poison
Lead poisoning - inhibits ALAD and ferrochetalase
Vitamin B6 def - needed for ALAS

Question 15

Lab findings in sideroblastic anemia

Answer 15

Increased ferritin
decreased TIBC
increased serum iron
increased iron saturation

Question 16

HbF

Answer 16

alpha 2 gamma 2

Question 17

HbA

Answer 17

alpha 2 beta 2

Question 18

HbA2

Answer 18

alpha 2 delta 2

Question 19

cause of alpha thalassemia

Answer 19

gene DELETION

Question 20

cause of beta-thalassemia

Answer 20

gene MUTATION

Question 21

What chromosome has the alpha genes?

Answer 21

16

Question 22

What chromosome has the beta genes?

Answer 22

11

Question 23

Presentation if one alpha gene is deleted?

Answer 23

asymptomatic

Question 24

Presentation if two alpha genes are deleted?

Answer 24

mild anemia with increased RBC count

Question 25

who more commonly has cis deletion of alpha gene?

Answer 25

asian persons

Question 26

who more commonly has trans delation of alpha gene?

Answer 26

african descent

Question 27

Presentation if three alpha genes are deleted?

Answer 27

severe anemia | Beta chains form tetramers (HbH) that damage RBCs

Question 28

Presentation if four alpha genes are deleted?

Answer 28

Hydrops fetalis in utero -- gamma chains form tetramers that damage RBCs

Question 29

HbH

Answer 29

tetramers of beta chains

Question 30

Hb Barts

Answer 30

tetramers of gamma chains

Question 31

beta thalassemia minor presentation

Answer 31

mild disease usually asymptomatic with increased RBC count

Question 32

what will hemoglobin electrophoresis show in Beta thalassemia minor?

Answer 32

increased HbA2 and increased HbF

Question 33

explain the pathophys of Beta-thalassemia major

Answer 33

Most severe form of disease. Unpaired alpha chains precipitate and damage RBC membranes causing ineffective erythropoiesis and intravascular hemolysis

Question 34

Presentation of beta-thalassemia major

Answer 34

Massive erythroid hyperplasia --> crewcut appearance from hematopoiesis in the skull, chipmunk facies, hepatosplenomegaly, risk of aplastic crisis from parvovirus