Module 2: Hypochromic Anemias

Question 1

Disorders of iron metabolism (2)

Answer 1

Iron deficiency anemia (IDA)

• decreased dietary iron
• blood loss
• impaired iron transport

Anemias of chronic disease (ACH)

• Chronic inflammatory diseases
• Malignant disorders

Question 2

Disorders of Heme synthesis (Sideroblastic anemias) (3)

Answer 2

Hereditary Sideroblastic Anemia
Idiopathic Sideroblastic Anemia
Secondary Sideroblastic Anemia
-Drug induced
-Alcohol induced
-Lead poisoning

Question 3

Disorders of Globin synthesis (thalassemias) (3)

Answer 3

Beta thalassemia
alpha thalassemia
other thalassemia

Question 4

Function of iron (3)

Answer 4

formation of heme
component of cytochromes, catalase, myeloperoxidase
Enzyme activator in some reactions

Question 5

Total body iron content in adults

Answer 5

2-5grams

Question 6

Iron distribution % in the body

Answer 6

Heme (enzymes, hemoglobin, myoglobin) 80%

Transport (transferrin) 0.1%

Storage (spleen, liver, other) 20%

Question 7

Source of daily iron

Answer 7

diet provides 15mg per day
5-10% of this is absorbed into circulation (1.0-1.5mg)

Pregnant and menstruating women need more

Question 8

where is iron mostly absorbed

Answer 8

mostly in duodenum and jejunum

Question 9

What is iron absorption dependent on (3)

Answer 9

serum iron concentration (inversely): Amount of circulating iron

Amount in the diet (directly)

pH in the gut - an acid pH enhances absorption (inversely)

Question 10

Other things that may vary iron absorption

Answer 10

Reducing agents that enhance it (vit c)

Phytates and phosphates form insoluble iron complexes that decrease absorption

Alcohol enhances absorption by stimulating Hal secretion

Large amount of dairy product interfere with conversion of ferric iron to ferrous iron

Question 11

What state must iron be in to be absorbed

Answer 11

reduced, ferrous state (Fe 2+)

Question 12

Iron transport

Answer 12

in plasma, iron is transported by transferrin to areas of utilization (NRBC in BM, storage in macrophages and hepatic cells)

Question 13

normal transferrin saturation with iron

Answer 13

30%

meaning 30% of the iron binding sites available on transferrin are occupied by iron

Question 14

2 forms of Iron storage

Answer 14

ferritin (major normal storage form)

Hemosiderin

Question 15

Ferritin

Answer 15

water soluble (temporary) storage of iron in NRBC, intestinal mucosal cells, renal tubular cells, plasma and macrophages (mostly in liver and spleen)

Not large enough to be visible in RBC

Question 16

when is ferritin converted to hemosiderin

Answer 16

prolonged storage

Question 17

Hemosiderin

Answer 17

water insoluble storage of iron
Formed in macrophages by polymerization of many ferritin into large dense iron aggregates
Visible in cells using Prussian blue stain

Presence may indicate iron overload

Question 18

Pappenheimer bodies

Answer 18

hemosiderin in cells when stained with wrights stain

Question 19

Iron excretion

Answer 19

no form of excretion

Some is lost every day and must be replaced by diet or iron stores will be depleted

Question 20

Causes of iron deficiency (4)

Answer 20

decreased intake
incomplete or inadequate absorption
increased utilization
iron loss

Question 21

Cause of Iron deficiency: Decreased Iron intake

Answer 21

Nutritional deficiency
Most common cause of IDA in infants

Due to: Malabsorption, elderly and impoverished, fad diets, meat poor diets

Question 22

Cause of Iron deficiency: Incomplete or inadequate iron absorption

Answer 22

Iron is not absorbed in GI tract

Due to: Celiac disease, resection of small bowel, absence of factors required for absorption

Question 23

Cause of Iron deficiency: Increased iron utilization

Answer 23

Increased demand for iron that is not met

Due to: Pregnancy, growth spurts, increased need of RBC regeneration

Question 24

Cause of Iron deficiency: Iron loss

Answer 24

Acute or chronic bleeding (most common cause of IDA in canada)

Due to: GI/ urinary bleed, intravascular hemolysis, malignancy, menstruation, pregnancy

Question 25

Iron deficiency anemia

Answer 25

an anemia of severely decreased or absent body iron stores results in decreased heme formation in developing NRBC as well as hypochromia and microcytosis in mature RBC

Question 26

Hypochromia

Answer 26

red cells with increased central pallor, indicating they contain less hemoglobin than normal

Question 27

3 stages of Iron deficiency anemia

Answer 27

iron depletion iron deficiency iron deficiency anemia

Question 28

Iron depletion stage of IDA lab results

Answer 28

Stage 1 Hb N Serum iron N TIBC (total iron binding capacity) N Ferritin Decreased

Question 29

Iron deficiency stage of IDA lab results

Answer 29

Stage 2 Hb N Serum iron Decreased TIBC Increased Ferritin decreased

Question 30

Iron deficiency anemia lab results hematology

Answer 30

Hb decreased Hit decreased RBC indices decreased RBC morph: Mild: hypochromia, microcytosis Severe: plus ovalocytes and target cells

Question 31

Iron deficiency anemia lab results chemistry

Answer 31

Iron Assay Decreased TIBC increased Transferrin saturation decreased Ferritin decreased sTfR increased FEP increased

Question 32

Iron assay

Answer 32

measures amount of circulating iron that is bound to transferrin

Question 33

TIBC total iron binding capacity

Answer 33

measures ability of transferrin to carry iron

Question 34

Transferrin saturation

Answer 34

measured as percentage Ratio of serum iron to TIBC (serum iron/TIBC) x100

Question 35

Serum ferritin

Answer 35

measurement of storage iron levels indirect method as levels reflect the levels of iron stores within cells

Question 36

sTfR Soluble Transferrin receptor

Answer 36

indicated number of RBC transferrin receptors are present on the cell

Question 37

Thalassemia

Answer 37

group of inherited disorders rate of synthesis of specific polypeptide chain (alpha or beta) use in global production in RBC is decreased Hypochromia, microcytic

Question 38

Sideroblastic anemia

Answer 38

caused by biochemical abnormalities in synthesis of heme NOT due to lack of iron Iron accumulates because protoporphyrin IX formation is decreased

Question 39

Classification of sideroblastic anemias

Answer 39

Refractory: inherited; idiopathic Secondary: due to Vit b6 deficiency, drugs/toxins that inhibit enzymes of heme synthesis (lead intoxication), malignancies

Question 40

3 ways lead disrupts normal function in Sideroblastic anemia of lead poisoning (plumbism)

Answer 40

1) interfere with enzymes of heme synthesis resulting in hypochromia 2) interfere with enzymes which normally depolymerize RNA in RBC resulting in basophilic stippling 3) interfere with membrane ATPase enzymes required for active transport = premature hemolysis of developing RBC and ineffective erythropoiesis

Question 41

Anemia of chromic disorders (3 causes)

Answer 41

seen in inflammatory diseases 1) inflammatory blockage of release of iron stores; mild accumulation of iron in storage areas and deficiency in developing RBC 2) Increase hemolysis of RBC 3) Decreased erythropoietin production

Question 42

Lab results of Iron Deficiency Anemia (IDA)

Answer 42

``` Serum Iron: D TIBC: I Transferrin saturation: D Serum ferritin: D sTfR: I Storage iron (BM iron stain): absent ```

Question 43

Lab results of Beta Thalassemia

Answer 43

HB electrophoresis: Increased HbA2

Question 44

Lab results for Anemia of Chronic Disease (ACD)

Answer 44

``` Serum Iron: D TIBC: D Serum Ferritin: I FEP: I Storage iron (BM iron stain): normal in macrophages; decreased in NRBC ```

Question 45

Lab results for Sideroblastic Anemias

Answer 45

``` Serum Iron: I TIBC: N Transferrin saturation: I Serum ferritin: I sTfR: D Storage iron (BM iron stain): I RBC morph: dimorphic, basophilic stippling and pappenheimer bodies Bone marrow: Ringed sideroblasts ```