Microcytic Anemia - Iron Deficiency Anemia

Question 1

What is the cause of all microcytic anemias and what effect does that have on the RBC? Essentially, how do we get smaller RBCs because of this cause?

Answer 1

Erythroblast is the progenitor cell of RBCs. They are much larger, but they divide a ton, producing smaller RBCs. Now, all microcytic anemias are due to a reduced production of hemoglobin. The effect is that each RBC will divide “an extra time” to maintain normal concentrations of HgB. So the RBCs are smaller.

Question 2

Explain the simple biochemistry of hemoglobin, what it is made of, and how this leads to our types of microcytic anemia?

Answer 2

Hemoglobin is made up of heme and globin. Heme is made up of iron and protoporphyrin. Any decrease in any of the components making up hemoglobin will lead to a microcytic anemia.

1. Iron deficiency anemia
2. Anemia of chronic disease, which traps iron in cells or makes the iron unavailable
3. Sideroblastic anemia, which is low proto
4. Thalassemia, which is low globin.

Question 3

What is the most common type of anemia and what is the most common nutritional deficiency in the world?

Answer 3

Iron deficient anemia

Iron deficiency

Question 4

Explain where we get iron from, how we absorb it and how it is stored?

Answer 4

We either get it in the heme form, from meat, or the non heme form, from vegetables.
It is absorbed in the duodenum via enterocytes which have both heme and non heme transporter on the lumen side to bring iron into the enterocyte. The heme form is more readily absorbed.
Because we really don’t have a mechanism in the body to get rid of iron, we have to be careful with how much iron we take in. The enterocytes have ferroportin on the blood side which dictates how much iron is released from the enterocyte into the blood.
Once in the blood, it is bound to transferrin and transported in the blood to the liver and bone marrow macrophages for storage and is fond to ferritin.

Question 5

What do the following lab values tell us about iron?
Serum iron
TIBC
% saturation
Serum ferritin

Answer 5

Measure of iron in the blood
Unbound and bound transferrin. This is our binding capacity for iron
How much transferrin is actually bound by iron
Reflects iron stores in macrophages and liver

Question 6

What two things usually cause iron deficiency?

Answer 6

Dietary lack or blood loss

Question 7

What is the specific cause in the following age groups for iron deficiency?
Infants, children, adults (20-50), elderly

Answer 7

Breast feeding , breast milk very low in iron
Poor diet
Peptic ulcer disease in males and menorhagia or pregnancy in females
Colon polyps/carcinoma in western world and hook worms in developing world (ancylostoma and necator two common worms )

Question 8

What is the other high yield cause of iron deficiency he mentioned and what is the mechanism of it?

Answer 8

Gastrectomy.
Stomach acid encourages the Fe2+ state of iron and that is the state more easily absorbed. When you take part of the stomach out, you might have less acid which in turn would encourage the Fe3+ state and not so easily absorbed.

Question 9

Explain the 4 stages of iron deficiency and how it lead to anemia?

Answer 9

1. When there is a drop in iron throughout the body, the storage anemia is used up first, resulting in less ferritin bound iron and an increased production of transferrin to go find more iron and bring it into storage.
2. Next, the serum iron is depleted so serum iron goes down and saturation goes down.
3. The bone marrow still needs to make RBCs, but there is a problem…not enough iron. So the bone marrow says, OK we will still make RBCs in normal size but fewer, so there is a normocytic anemia.
4. The iron deficiency is so bad that it will have no choice but to make smaller RBCs with less hemoglobin, so there will be a microcytic hypochromic anemia.

Question 10

3 common clinical signs/symptoms of iron deficiency anemia?

Answer 10

Anemia, koilonychia (spoon shaped fingernails), and pica (chewing on weird things like dirt)

Question 11

What 7 lab values will we see for iron deficiency anemia?

Answer 11

Microcytic hypo chromic RBC
Increased RDW
Low ferritin
Increased transferrin
Low serum iron
Low saturation
Increased free protoporphyrin

Question 12

2 thing to consider with with treatment of iron deficiency anemia?

Answer 12

Supplement with ferrous sulfate and treat the underlying issue causing the low iron

Question 13

What is the high yield syndrome that is associated with iron deficiency anemia, what are the three problems in the syndrome and what are the three symptoms?

Answer 13

Plummer Vinson syndrome
Iron deficiency anemia, esophageal web and glossitis
Anemia, dysphagia and beefy red tongue