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Pathology Post Midterm > Module 1: Thalassemia and Iron deficiency Anemia > Flashcards

Module 1: Thalassemia and Iron deficiency Anemia Flashcards

1
Q

Starting off with the microcytic hemolytic anemias is Alpha Thalassemia, what is the etiology of this?

A

Deletion mutations on chromosome 16 to any number of the 4 alpha globin genes, which leads to decreased synthesis of alpha globin and accumulation of unpaired Beta globin chains

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2
Q

What are the four different types of Alpha Thalassemia?

A
  1. Silent Carrier: 1 alpha gene deleted (Asymptomatic)
  2. Alpha thalassemia trait: Two genes deleted
    - – alpha/alpha and -/- (SE Asian) CIS
    - – alpha/- and alpha/- (African) TRANS
    - –mild anemia with increased RBC count
  3. Hemoglobin Hd: 3 genes affected; severe anemia
    - –B chain form tetramer (HbH) — high affinity O2 – severe tissue hypoxia
    - –HbH is prone to oxidation – precipitated inclusions in older RBCs — extravascular hemolysis
  4. Hydrops Fetalis= lethal in utero; 4 genes deleted
    - -gamma chains form tetramers (Hb Barts) – extremely high affinity for 02 — no O2 reaches tissues
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3
Q

The next hypochromic microcytic anemia is Beta Thalassemia, with extravascular hemolysis. What is the etiology of this anemia?

A

Decreased synthesis of structurally normal beta globin chains due to point mutations in chromosome 11 in promotor or splicing sites

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4
Q

Inadequate levels of B-globin leads to what?

A

unpaired alpha globin chains

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5
Q

Explain B+ and B0

A

B+ : decreased beta chains produced – mutation in promotor region of gene
B0: no beta chains (homozygous)-mutation in splicing or chain termination

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6
Q

What types of ppl get beta thalassemia?

A

Mediterranean and S.E. asian males

–autosomal recessive

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7
Q

There are two types of Beta thalassemia, what are these types?

A

Minor or Trait: B0/B or B+/B – mild asymptomatic anemia (one normal beta chain and one dimished (+) or absent (0) )
Major: B0/B0 or B+/B+ — severe transfusion dependent anemia (Abnormal in causes occlusion in small blood vessels)(no beta chains period)

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8
Q

As mentioned before beta thalassemia major is predominately extravascular hemolysis, so therefore what signs will you see in the patient?

A

Splenomegaly (again this is happening in the spleen) causing a dragging pain in the LUQ
Chronic Hemolytic Anemia (spleen is destroying the RBCs)
—splenic macrophages are eating the defective RBC causing splenomegaly

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9
Q

Beta thalassemia major also involves extramedullary hematopoiesis, what does this involve?

A

Eventually the liver and spleen starts compensating for the lysing and decreased RBC so more hematopoietic cells are made causing hepatosplenomegaly.
–also causes lymphadenopathy

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10
Q

Patient with beta thalassemia major also have frontal bossing seen on examination (called crew cut appearance on xray) and chipmunk faces, what is this due to?

A 
Expansion of the hematopoietic marrow in the skull via two mechanisms: 
Intramedullary hematopoiesis (erythroid hyperplasia): Bone marrow is making more reticulocytes due to increased destruction of RBCs. 
Intramedullary hemolysis (aka ineffective erythropoiesis): alpha chain tetramers break RBCs before they leave the marrow.
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11
Q

What are other signs and symptoms in a patient with beta thalassemia?

A

Jaundice (Due to the unconjugated bilirubin)
Fatigue
Hepatomegaly
Failure to thrive in small kids

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12
Q

Electrophoresis is the best investigation for beta thalassemia, what is seen?

A

Major: very prominent HbF and small amount of HbA2 (if B0/B0 then no HbA at all; if B+/B+ then a very small amount of HbA)
Minor: HbA2 small amount, small amount of HbF and still majority HbA

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13
Q

What do you see on peripheral blood smear in a patient with thalassemia major?

A
  • -Anisopoikilocytosis (RBCs of different shapes and sizes) causes an increase in RDW
  • –Reticulocytosis (Due to the intramedullary hematopoiesis)
  • –Target cells ( Hb settling in the center of the cell)
  • –Normoblasts (due to the Intramedullary hemolysis )
  • -Hypochromic microcytic RBCs (decreased MCHC due to decreased Hb and decreased MCV)
  • -Howell Jolly Bodies (because the spleen is getting over worked)
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14
Q

What is seen in regards to lab values in these patients?

A

Increased LDH
Increased Potassium
Increased Serum Iron
Increased Ferritin (protein that stores iron in the liver)
Increased reticulocytes
Increased RDW
Decreased TIBC (total iron binding capacity)

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15
Q

Patients with beta thalassemia major need repeated blood transfusions, why?

A

Due to lack of HbA (worst type of anemia)

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16
Q

What do patients with beta thalassemia major die from?

A

Most common cause of death is CHF secondary to hemochromatosis
—in a state of iron overload and keep getting blood transfusions so more and more overload of iron — decreased hepcidin

17
Q

What are the complications of beta thalassemia major?

A
  1. Hemochromatosis: bronze skin, diabetes, arthritis, restrictive cardiomyopathy, liver cirrhosis, pseudogout
  2. Shuts down anterior pituitary: no TSH so thyroid gland atrophies and therefore secondary hypothyroidism ; no LH so testicular atrophy and infertility; no ACTH so secondary adrenal cortical insufficiency so low cortisol
  3. Bilirubin gallstones (Cholelithiasis)
  4. Encapsulated bacterial infections
  5. Aplastic crisis (Parvo B19 - causing reticulocytopenia)
  6. Sepsis due to iron loving bacteria: Vibrio Vulnificus and Yersinia Enterolytica (mimics acute appendicitis)
  7. Megoblastic anemia due to using up all the folate in the body
18
Q

What is treatment for beta thalassemia major?

A

Iron Chelators
Folate supplements
vaccinations
blood transfusions

19
Q

The next anemia that will be discussed is iron deficiency anemia, which is what type of anemia?

A

Microcytic Hypochromaic Anemia

20
Q

There are 4 etiologies for iron deficiency anemia each card will go through one. The first etiology is…

A
  1. Nutritional deficiency: very common in children—most of iron intake is from meat as heme iron and grains as stored non heme iron so its okay to give kids meat.
21
Q

The 2nd etiology for iron deficiency anemia is….

A
  1. Malabsorption: Iron is absorbed in duodenum
    - –Crohns Disease
    - -Celiac Sprue (gluten sensitive entropathy)
    - –Tropical Sprue (bacterial)
    - –Whipple’s (gram positive bacteria common in white men)
22
Q

3rd etiology for iron deficiency anemia is …

A
  1. Increased demand
    - -pregnant women
    - -growing infants and children
    - -pre-menopausal women
23
Q

4th etiology for iron deficiency anemia is..

A
  1. Chronic blood loss
    - –Right sided colon cancer (Due to occult blood)
    - –Uterine fibroids in nulliparous black women who get heavy periods
    - –Peptic ulcer causes melena
    - -Gastric cancer or esophagus cancers
24
Q

Plummer Vision Syndrome is super un common but happens mostly in middle aged women , what is the triad of etiologies?

A
  1. Iron deficiency anemia (fatigue)
  2. Glossitis: beefy tongue
  3. Esophageal Webbing: dysphagia
25
Q

How does a patient with iron deficiency anemia present?

A

Just fatigue

  • -no jaundice due to no elevation in bilirubin
  • -no megaly
  • -normal urine
  • -normal LDH and bilirubin
26
Q

What is the best investigation for iron deficiency anemia?

A

Bone marrow biopsy with Prussian Blue staining (Way to invasive to do clinically)
–hypocellular bone marrow because its a production problem not enough iron to make red cells.

27
Q

What are the lab values for a patient with iron deficiency anemia?

A

Storage Iron is depleted: so decreased ferritin and increased TIBC
Serum Iron is depleted: low serum iron and low % saturation

28
Q

What is seen on peripheral blood smear in patients with iron deficiency anemia?

A

Poikilocytosis (elevated RDW)
Pencil Red Cells
Hypochromic (low MCHC–decreased Hb)
Microcytic (low MCV–small RBC)
Thrombocytosis (idiopathic–elevated platelet count)
Reticulocytopenia (no iron to make reticulocytes)

29
Q

What are the complications for iron deficiency anemia?

A
  1. CHF
  2. Esophageal webs can become squamous carcinoma of the esophagus
  3. Pica (eat soil/dirt) due to the chronic iron deficiency
  4. Spooning of Fingernails: Koilonychia
30
Q

Pregnant women need iron supplements as well as what?

A

Vit C this is for them to be able to absorb iron in the duodenum

31
Q

What is the normal iron metabolism?

A

Iron is absorbed in the duodenum. Nonheme iron is carried across the apical and basolateral membranes of enterocytes by transporters

  • –after reduction by ferric reductase, ferrous iron (Fe2) is transported across the apical membrane
  • –A second transporter, ferroportin, then moves iron from the cytoplasm to the plasma across the basolateral membrane
  • -the newly absorbed iron is next oxidized by hephaestin and ceruloplasmin to ferric iron (Fe3), this binds to transferrin.
32
Q

What is the pathogenesis for iron deficiency anemia?

A

decreased iron —- decreased heme —- decreased hemoglobin — microcytic anemia

33
Q

When the body is replete with iron, what happens?

A

Most iron entering duodenal cells is handed of to ferritin and transfer to plasma transferritin is enhanced when iron is deficient or erythropoiesis is inefficient

34
Q

Explain the role of hepcidin in iron?

A

A small hepatic peptide that is synthesized and secreted in an iron dependent fashion

  • -plasma hepcidin binds ferroportin and induces its internalization and degradation
  • -when hepcidin levels fall the basolateral iron is increased eventually leading to systemic iron overload

Pathology Post Midterm (50 decks)

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