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Review / Wrong Answers > Pathoma - RBC Disorders - Micro- and Macrocytic Anemia > Flashcards

Pathoma - RBC Disorders - Micro- and Macrocytic Anemia Flashcards

1
Q

What is the underlying cause of microcytic anemia?

A

Decrease in hemoglobin

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2
Q

What are the 4 types of microcytic anemia?

A

(1) Iron deficiency anemia
(2) Anemia of chronic disease (iron is unavailable for use)
(3) Sideroblastic anemia (decreased protoporphoryin)
(4) Thalassemia

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3
Q

Where does absorption of iron occur?

A

Duodenum

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4
Q

What are the proteins involved in iron absorption and transport?

A

Ferroportin (transports iron from gut lumen to blood)

Transferrin (transports iron within the blood)

Ferritin (stores intracellular iron)

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5
Q

Describe iron lab measures:

  • Serum iron
  • Total-iron binding capacity (TIBC)
  • % saturation
  • Serum ferritin
A

Serum iron = iron in the blood

TIBC = transferrin molecules in the blood

% saturation = percentage of transferrin molecules bound to iron

Serum ferritin = iron stores

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6
Q

How does a gastrectomy effect iron levels?

A

Gastric acids allow iron to maintain Fe2+ state, which is the form that can be absorbed (Fe2 go in TO the body)

Gastrectomy can cause iron deficiency because no acid means iron will be in Fe3+ form

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7
Q

Lab values in iron deficiency anemia:

  • Serum iron
  • Total-iron binding capacity (TIBC)
  • % saturation
  • Serum ferritin
  • RDW
  • Free erythrocyte protoporphyrin
A

Serum iron - decreased

Total-iron binding capacity (TIBC) - increased (liver pumps out more transferrin in search of iron)

% saturation - decreased

Serum ferritin - decreased

RDW - increased (due to normocytic anemia early in disease and microcytic later in disease)

Free erythrocyte protoporphyrin - increased

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8
Q

What is Plummer-Vinson syndrome

A

Iron deficiency anemia with esophageal web and atrophic glossitis

Presents as anemia with dysphagia and beefy-red tongue

Think: a plumber with bad breath (esophageal web), and plumber is pale (anemia) and fat with a big red tongue (glossitis)

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9
Q

Describe the role of Hepcidin in anemia of chronic disease

A

Liver will produce acute phase reactants such as Hepcidin, which will sequester iron in storage sites

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10
Q

Lab values in anemia of chronic disease:

  • Serum iron
  • Total-iron binding capacity (TIBC)
  • % saturation
  • Serum ferritin
  • Free erythrocyte protoporphyrin
A

Serum iron - decreased

Total-iron binding capacity (TIBC) - increased

% saturation - decreased

Serum ferritin - increased

Free erythrocyte protoporphyrin - increased

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11
Q

What is the cause of sideroblastic anemia

A

Defective protoporphyrin synthesis

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12
Q

Describe the steps of protoporphyrin synthesis + it’s attachment to iron

A

All occurs in the mitochondria:

Succinyl CoA converted to aminolevulinic acid (ALA) via Aminolevulinic acid synthetase (ALAS)

ALA converted to prophobilinogen via ALAD

Prophobilinogen converted to proptoporphyrin

Protoporphyrin attached to iron via ferrochelatase

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13
Q

What are ringed sideroblasts and how do they form?

A

Protoporphyrin deficiency wi;; cause iron to build up inside mitochondria, where they would usually be bound to protoporphyrin

Iron-laden mitochondria form a ring around the nucleus

Seen with Prussian blue stain

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14
Q

Lab values in sideroblastic aneia:

  • Serum iron
  • Total-iron binding capacity (TIBC)
  • % saturation
  • Serum ferritin
A

Serum iron - increased

TIBC - decreased

% sat - increased

Serum ferritin - increased

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15
Q

How does Thalassemia cause anemia?

A

Decreased SYNTHESIS of globin chains

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16
Q

What type of gene defect causes alpha-thalassemia

A

Gene deletion

17
Q

What population is associated with Cis- and Trans- alpha thalassemia 2 gene deletion

A 
Cis = Asians
Trans = Africans
18
Q

What causes damage in 3 gene deletion a-thalassemia?

A

HbH (beta tetramers) will damage RBCs

19
Q

What causes damage in 4 gene deletion a-thalassemia?

A

Hb Barts (gamma tetramers) will damage RBCs

Lethal in utero (hydrops fetalis)

20
Q

What type of gene defect causes beta-thalassemia

A

Gene mutation

21
Q

What are the possible results of mutation in beta-thalassemia

A 
B0 = absent globin chain
B+ = diminished production of globin chain
22
Q

What will RBCs look like in beta-thalassemia minor (B/B+)

A

Microcytic, hypochromic RBCs with target cells (decreased hemoglobin in cytoplasm allows for membrane blebbing)

23
Q

What types/levels of hemoglobins will you see in beta-thalassemia minor?

A

Slightly decreased HbA (a2b2)

Increased HbA2 (a2d2)

Increased HbF (a2y2)

24
Q

What is the damage in b-thalassemia major (B0/B0)

A

Unpaired alpha chains will precipitate and damage RBCs, resulting in ineffective erythropoiesis and extravascular hemolysis

25
Q

Describe the cause and effect of erythroid hyperplasia in b-thalassemia major

A

Because there is such severe anemia, the body will try to even harder to make more RBCs and erythropoeisis will begin to take place in locations other than the norm (central axial skeleton), such as:

  • skull (‘crewcut’ appearance on x-ray)
  • facial bones (‘chipmunk faces’)
  • extramedullary areas (hepatosplenomegaly)
26
Q

What types of cells will you see in b-thalassemia major

A

Microcytic, hypochromic RBCs with target cells

Nucleated RBCs (more easily escape from the locations of abnormal hematopoiesis)

27
Q

What type of hemoglobin will you see in b-thalassemia major

A

Little or no HbA

Elevated HbA2 and HbF

28
Q

What is the underlying cause behind macrocytic anemia and what are the causes

A

One less division of RBCs

Usually caused by Folate or B12 deficiency (necessary for DNA precursors)

Can also be cause by alcoholism, liver disease, and drugs

29
Q

What is megaloblastic anemia and what are the defining features

A

A macrocytic anemia caused by Folate or B12 deficiency that also causes megaloblastic change in other rapidly dividing cells

This is because Folate and B12 are needed to DNA synthesis in all cells, not just RBCs

Defining features:

  • Megaloblastic anemia
  • Hypersegmented neutrophils
  • Megaloblastic change in rapidly-dividing (e.g. intestinal) epithelial cells
30
Q

Folate:

  • Source
  • Site of absorption
  • Stores
A

Folate found in green vegetables

Absorbed in the jejunum

Liver stores lasting 3-4 months

31
Q

Clinical and lab findings in folate deficiency

A
  • Macrocytic RBCs with hypersegmented neutrophils
  • Glossitis (inflammation of tongue because cells are not turning over as quickly)
  • Decreased serum folate
  • Increased serum homocysteine
  • Normal methylmalonic acid (vs. B12 deficiency which will have elevated)
32
Q

Describe the steps of Vitamin B12 (cobalamin) absorption

A

Dietary B12 complexed to meat products

Salivary amylase breaks B12-meat complex and saliva also produces R-binder to attach to B12 for travel through the stomach

Pancreatic proteases in the duodenum detach B12 from R-binder

B12 complexed with IF (made in parietal cells) can be absorbed in the ILEUM

33
Q

What is the body store of B12

A

Large hepatic stores (3-4 years)

34
Q

What is pernicious anemia

A

Autoimmune destruction of parietal cells leads to decreased IF production, so B12 cannot be absorbed, leading to megaloblastic anemia

35
Q

Describe 3 causes (other than pernicious anemia) that can lead to B12 deficiency

A

(1) Pancreatic insufficiency (no proteases to cleave B12 from R-factor)
(2) Damage to the terminal ileum, site of B12 absorption (e.g. Crohn’s Diphyllobathrium latum)
(3) Dietary deficiency (rare) - vegans

36
Q

Clinical and lab findings in Vitamin B12 deficiency

A
  • Macrocytic RBCs with hypersegmented neutrophils (megaloblastic anemia)
  • Glossitis (inflammation of tongue because cells are not turning over as quickly)
  • Decreased serum folate
  • Increased serum homocysteine
  • Increased methylmalonic acid (vs. Folate deficiency which will have normal)
  • Subacute combined degeneration of the spinal cord due to methylmalonic building causing destruction of myelin
  • Leads to poor proprioception and vibratory sense (posterior column) and spastic paresis (lateral corticospinal tract)

Review / Wrong Answers (140 decks)

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