Topic 4: Iron Deficiency Anemia

Question 1

why does an iron deficiency lead to decreased heme production?

Answer 1

heme is the iron-containing component of the hemoglobin protein that’s made via heme synthesis pathway

Fe is a substrate for the enzyme ferrochelatase in the final step of heme synthesis

deficiency of iron will impair this process and result in decreased heme production

Question 2

what compensatory mechanisms does the body have during anemia to maintain oxygen delivery to tissues?

Answer 2

1. increase in cardiac output
2. increased oxygen extraction by tissues
3. right shift of oxyhemoglobin curve - this graph measures hemoglobin oxygen
   saturation as a function of the partial pressure of oxygen

a right shift decreases hemoglobin’s affinity for oxygen and allows for increased oxygen unloading from hemoglobin

if anemia develops rapidly (like from hemorrhage) the patient will be symptomatic but if anemia onset is gradual, these compensatory mechanisms will be able to maintain oxygen delivery

Question 3

what is anemia?

Answer 3

a condition in which there is a reduction in RBC number or hemoglobin concentration

Question 4

what are the causes of iron deficiency?

Answer 4

1. blood loss
2. decreased nutritional intake
3. increased iron requirement

Question 5

what is blood loss often due to?

Answer 5

1. menses, trauma, hematemesis
2. frequent blood donation
3. occult GI bleeding
4. parasitic hookworm in tropical areas

Question 6

what populations have an increased iron requirement?

Answer 6

1. children

2. pregnant women

Question 7

Why do iron-deficient patients develop anemia?

Answer 7

Iron is a required substrate in the synthesis of heme, which is a major component of hemoglobin. If iron is deficient, hemoglobin synthesis will be impaired

Anemia occurs when the hemoglobin concentration drops below the normal reference range.

Question 8

what are common symptoms of IDA?

Answer 8

fatigue, weakness, lightheadedness, shortness of breath on exertion, and exercise intolerance

craving for ice = pagophagia

pallor, dry skin, spoon nails (koilonychia)

Question 9

what is Plummer-Vinson syndrome?

Answer 9

chronic iron deficiency anemia associated with glossitis and esophageal web with accompanying dysphagia and fatigue

at risk for developing squamous cell carcinoma of the esophagus

treatment: iron supplement and esophageal dilation to alleviate dysphagia

Question 10

how are Hb and hematocrit levels on the CBC of an IDA patient effected?

Answer 10

hemoglobin and hematocrit are decreased

Question 11

how is the RBC count on the CBC of an IDA patient effected?

Answer 11

RBC is also decreased, since the main problem is that it’s hard to make red cells

Question 12

how is the size of RBC of IDA patient effected?

Answer 12

microcytic and MCV is low too (<80)

because there’s a problem making Hb

Question 13

how is RDW in IDA effected?

Answer 13

RDW is increased

RDW measures how much the red cells vary in size

in IDA there are some little cells and some bigger cells and the RDW is high = anisocytosis

anisocytosis happens in IDA because each new wave of red cells produced is smaller than the last

Question 14

how is the reticulocyte count in IDA effected?

Answer 14

decreased

you can’t make enough red blood cells because there’s not enough iron around

Question 15

what iron studies can definitively confirm IDA?

Answer 15

CBC isn’t enough because it may have similarities to ACD

1. serum iron
2. TIBC
3. serum ferritin
4. % transferrin saturation

Question 16

how is the serum iron in IDA effected?

Answer 16

decreased

non-diagnostic alone because iron is decreased in both iron deficiency and anemia of chronic disease

Question 17

how is the TIBC in IDA effected?

Answer 17

TIBC increases

this is a measure of how many binding sites are available for iron on the transferrin molecule

in iron-deficiency anemia, since there is little iron around, the TIBC goes up

Question 18

how is the serum ferritin in IDA effected?

Answer 18

decreased ferritin levels

ferritin is an iron storage protein that is proportional to total body iron stores

low ferritin is virtually diagnostic for iron deficiency

sometimes though, ferritin can be elevated in conditions like systemic inflammation so a normal or high ferritin level doesn’t rule out IDA

so if ferritin is low, definitely IDA

but if ferritin is normal or high, you don’t know if it’s IDA or not

Question 19

how is % transferrin saturation effected in IDA?

Answer 19

it’s decreased

since there is little iron around, the percent of transferrin binding sites that are saturated with iron is low

Question 20

Which parameter on iron panel is most reliable for determining iron deficiency?

Answer 20

Serum ferritin is most reliable because low levels are highly specific for iron deficiency

Question 21

what does an IDA blood smear show?

Answer 21

1. less RBCs = lots of white space between cells
2. RBCs look paler due to decreased Hb content = hyperchromic
3. anisocytosis
4. elliptocytes
5. reactive thrombocytosis may be present

Question 22

how do you evaluate chromasia of RBC?

Answer 22

chromasia = amount of Hb in RBC

look at the zone of central pallor which should be 1/3 of cell diameter

in IDA, zone of pallor is increased

Question 23

what is anisocytosis?

Answer 23

that a patient’s red blood cells are of unequal size

Question 24

can you see anisocytosis in blood smear of IDA?

Answer 24

yup

there are some little cells (these are the newer ones) and some larger ones (these are older, and are bigger because there was more iron around then)

Question 25

what is the feared cause of IDA in older males or post-menopausal women

Answer 25

occult gastrointestinal bleeding from a gastrointestinal malignancy such as colon cancer

should be evaluated with a colonoscopy to rule out any potential bleeding or masses

Question 26

how do you treat IDA?

Answer 26

figure out the underlying cause

once the cause of iron deficiency is identified, treatment is targeted towards the underlying etiology in addition to supportive treatment, including iron replacement

Question 27

when would iron supplement be given via IV instead of orally?

Answer 27

given to patients who cannot tolerate oral iron or those with inflammatory bowel disease, gastric bypass surgery, or malabsorption syndromes

Question 28

what impairs absorption of iron if it’s given orally?

Answer 28

Calcium, phytates, and tannates

so iron shouldn’t be given with milk, eggs, or cereal

Question 29

what enhances iron absorption if it’s given orally?

Answer 29

iron absorption is enhanced in an acidic environment

so it’s usually given with vitamin C or orange juice

Question 30

what are some side effects of oral iron supplements?

Answer 30

• gastrointestinal upset
• constipation,
• dyspepsia
• nausea