Microcytic Anemias

Question 1

What are the types of microcytic anemia?

Answer 1

Iron deficiency
ACD
Thalassemia
Sideroblastic anemias

Question 2

What is the most common and least common type of microcytic anemia?

Answer 2

Most- iron deficiency

Least- sideroblastic anemias

Question 3

Detail the pathogenesis of microcytic anemias.

Answer 3

All are defects in Hb synthesis- heme + globin chains

Question 4

What microcytic anemias are due to defects in heme synthesis?

Answer 4

Iron deficiency
ACD
Sideroblastic anemia

Question 5

What microcytic anemias are due to a defect in globin chain synthesis?

Answer 5

Thalassemias

Question 6

Iron deficiency anemia is the most common overall anemia, what age ranges have the greatest disease prevalence?

Answer 6

Toddlers (inadequate intake)

Females (menstrual loss)

Question 7

What is the most common cause of iron deficiency?

Answer 7

GI bleed

Question 8

What are causes of iron deficiency?

Answer 8

Blood loss
Increased utilization
Decreased intake
Decreased absorption
Intravascular hemolysis

Question 9

Where is iron absorbed?

Answer 9

Duodenum

Question 10

Define koilonychia.

Answer 10

Spoon nails

Question 11

What makes heme?

Answer 11

Iron + protoporphyrin: enzyme is ferrochelatase

Question 12

What is the rate limiting enzyme in protoporphyrin synthesis?

Answer 12

ALA synthase

Question 13

What are the substrates to make ALA?

Answer 13

Succinyl-CoA + glycine + pyridoxine

Question 14

What are the 3 main causes of sideroblastic anemias?

Answer 14

EtOH- damages mitochondira
Vitamin B6 deficiency- inhibits ALA formation
Lead poisoning- inhibits ferrochelatase

Question 15

What populations are associated with α-thalassemia?

Answer 15

Asians (cis), Blacks (trans)

Question 16

Can you detect α-thalassemia on electrophoresis?

Answer 16

No, all forms of Hb are equally decreased

Question 17

There are 4 genes that control α-thalassemia, detail the conditions that result from gene deletions.

Answer 17

1 gene deletion: normal
2 gene deletion: mild anemia (α-thalassemia minor)
3 gene deletion: HbH disease (4 β chains)

Question 18

What is the treatment for α-thalassemia?

Answer 18

None- do not give iron

Question 19

α-thalassemia is due to gene deletions, contrast this with β-thalassemia.

Answer 19

β-thalassemia involves splicing defects, nonsense mutation (premature stop codon)

Question 20

WhatWhat populations are associated with β-thalassemia?

Answer 20

Blacks, Greeks, Italians

Question 21

Detail the electrophoresis pattern in β-Thal minor.

Answer 21

Decreased HbA

Increased HbA2 and HbF

Question 22

Detail the electrophoresis pattern in β-Thal major.

Answer 22

No HbA

Increased HbA2 and HbF

Question 23

If you have a β-δ thalassemia what does the electrophoresis show?

Answer 23

HbF

Question 24

What cell is commonly seen in all hemoglobinopathies?

Answer 24

Target cells

Question 25

What are the most common causes of iron deficiency in the following age groups: prematurity, newborn/child, woman under 50, man under 50 , men/woman over 50.

Answer 25

Prematurity- decreased iron 
Newborn/child- Meckel's diverticulum
Woman under 50- Menorrhagia 
Man under 50- PUD
Men/Woman over 50- colon cancer

Question 26

What is the most common nutritional deficiency in children worldwide?

Answer 26

Iron deficiency

Question 27

How do you check for a ringed sideroblast?

Answer 27

Bone marrow

Prussian blue

Question 28

Do you need to check for a ringed sideroblast in lead poisoning? Detail how you make the diagnosis.

Answer 28

No

Basophilic stippling of peripheral RBC- represents ribosomes

Question 29

What is the only heavy metal that deposits in the epiphysis of bone? What is the consequence of this in a child?

Answer 29

Lead

Failure to grow

Question 30

What do iron studies show in the sideroblastic anemias?

Answer 30

Serum iron- high
Serum ferritin- high
Iron saturation- high
TIBC- low
(iron overload disease)