Microcytic Anemias

Question 1

Reason for Microcytic Anemia

Answer 1

Decreased production of Hb. Extra division to concentrate the less Hb leaves microcytic cells.

Question 2

Iron Deficiency Anemia

Answer 2

Most common type of anemia and nutritional deficiency in world.
Sx: Anemia, Koilonychia, Pica
Labs: Microcytic, Hypochromic Anemia with Increase RDW + decrease ferritin, Increase TIBC, decrease %-Sat and increase FEP
Tx: Ferrous Sulfate + underlying

Question 3

Iron is consumed in 2 ways. 
Absorbed in which part of intestine.
Transported by which enzyme?
Carried in which protein?
Stored intracellular in protein?

Answer 3

meat derived Heme and Vegie derived non-heme. Heme is better absorbed in Duodenum, regulated by enterocyte.
Ferroportin used between entero and blood.
Transferrin transports iron in blood
Bound to Ferritin (or free radicals).

Question 4

Common Causes of Iron Deficiency

Dietary or Blood Loss

Answer 4

Infants = Breastfeeding
Children = Poor Diet
Adults = Peptic Ulcer Disease or Menorrhagia/Pregnancy
Elderly = Colon Polyps / Carcinoma or Hookworms (3rd world)
Also, Malabsorption or Gastrectomy (Acid maintains Fe2+ state)

Question 5

Stages of Iron Deficiency

Answer 5

1) Storage of Iron is Depleted (serum ferritin decreases, TIBC-transferrin goes up)
2) Serum Iron is Depleted (%-Sat goes down)
3) Normocytic Anemia
4) Microcytic, hypochromic anemia

Question 6

Plummer-Vinson Syndrome

Answer 6

Iron Deficiency Anemia with Esophageal Web and Atrophic Glossitis.
Presents with Anemia, Dysphagia and beefy-red tongue.

Question 7

Anemia of Chronic Disease (ACD)

Most common type of anemia in hospitalized patients.

Answer 7

Associated with chronic inflammation or cancer. Hepcidin guptas iron in storage sites. Limits transfer from macrophages to erythroid precursors and supresses EPO.
Normocytic, then Microcytic Anemia 
High Ferritin, Low TIBC
Low Serum Iron, Low % Sat
High FEP

Question 8

Sideroblastic Anemia leads to Microcytic Anemia

Answer 8

Defective Protoporphyrin Synthesis
Less Protoporphyrin 
Iron trapped in Mitochondria, creating Ring of Iron-loading Mitochondria around nucleus "Ringed Sideroblast."
Increase Ferritin, Decrease TIBC
Increase Serum Fe, Increase %-sat.

Question 9

Causes of Acquired Sideroblastic Anemia

Answer 9

1) Alcoholism - Mitochondrial Poison, decreasing synthesis.
2) Lead Poisoning - Denatures ALAD and Ferrochelatase
3) Vitamin B6 Deficiency - Cofactor for ALAS, rate-limiting step *Isoniazid

Question 10

Thalassemia

Answer 10

Decreased Synthesis of Globin Chains
Alpha and Beta Thalassemia
Alpha is Gene Deletion - CIS deletion is higher risk in Thalassemia in off-spring.
Beta from mutation on Chromosome 11.

Question 11

HbH on electrophoresis

Answer 11

HbH is a tetramer of Beta Globulin, resulting from lack of Alphas in Alpha Thalassemia. They damage RBCs.

Question 12

Hb Barts seen on electrophoresis

Answer 12

All 4 Alpha deleted, lethal in Utero (Hydrops Fetalis) where Gamma Chains form tetramers (damage RBCs)

Question 13

Target Cell

Answer 13

Results from Hb filling a bleb in the central pallor region from decreased cytoplasm or increased membrane. Hemoglobin C, Asplenia, Liver Disease, Thalassemia and severe Iron deficiency anemia.

Question 14

Massive Erythroid Hyperplasia

Answer 14

Expansion of hematopoeisis into marrow of skull and facial bones + liver and spleen (HSM) - Risk of aplastic crisis with Parvo B19. Circulating, nucleated RBCs. Seen in Beta Thalassemia Major.