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MBBS 3: Pediatrics > Anemia > Flashcards

Anemia Flashcards

1
Q

What is hematopoiesis?

A
  • formation of blood cellular components
  • derived from hematopoietic stem cells
  • largely controlled by feedback mechanism (cytokines)
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2
Q

What is Erythropoiesis?

A
  • the process which produces red blood cells
  • which is the development from erythropoietic stem cell to mature red blood cell
  • it is stimulated by decreased O2 in circulation which is detected by the kidneys which then secretes the hormone erythropoietin
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3
Q

Erythropoiesis through out life?
Which organs does it happen in?

A
  1. fetal
    - occurs in yolk sac, liver and spleen
    - At ~7 months moves to the BM and hepatic production decreases during the 3rd trimester and ceases soon after birth
  2. child
    - active bone marrow is present in all skeleton
  3. adult
    - active bone marrow is present in axial skeleton (head and trunk of vertebrae)
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4
Q

Erythropoiesis process?

A
  1. pluripotent hematopoietic stem cell
  2. proerythroblast
  3. erythroblast
    - loses nucleus + some organelles
    > processes above happen in bone marrow
  4. reticulocyte
    - spends 3 days in marrow, 1 day in blood
    - loses remaining organelles
  5. erythrocyte
    - lifespan aprox. 120 days (90 in an infant)
    > processes above happen in blood
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5
Q

Physiology of erythropoiesis?

A

Erythropoietin > hormone produced in the kidney
- Induces erythroid progenitor cells to differentiate into proerythroblasts
- Brings about expansion of the erythroid marrow and an increase in red cell production

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6
Q

Requirements for erythropiesis?

A
  1. Metals: Iron, cobalt, Mn.
  2. Vitamins: Vit B12, Folic acid, Vitamin C, Vitamin E Vit B6, Riboflavin.
  3. Amino acids
  4. Hormones: Erythropoietin, Androgens, Thyroxin
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7
Q

Structure of a normal erythrocyte?

A

Typically, without a nucleus.
Contain the pigment hemoglobin
Shape: Biconcave disks
Size:
~Diameter of 7.8um.
Thickness of 2.5um at the edge and 1um at the center
Volume: 90-95 m
Form: Flexible, deformable, elastic

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8
Q

Structure of RBC membrane?

A
  1. outer membrane
    - hydrophilic : glycolipids, glycoprotein, proteins
  2. inner layer
    - hydrophilic : proteins
  3. central layer
    - hydrophobic : proteins, cholesterol, phospholipids
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9
Q

RBC membrane function?

A

Maintain structure and contain the contents of the red cell- chiefly, hemoglobin.
Maintain cellular functions in transport of salts and nutrients.
Avoid adhesion to self and vascular wall
Deformability, metabolism, senescence
Provides cellular shape

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10
Q

What is hemoglobin?

A

iron containing oxygen transporting metalloprotein

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11
Q

2 parts of hemoglobin?

A
  1. Globin
    Consists of 4 polypeptide chains:
    Two alpha chains
    Two beta chains
  2. Heme
    Flat ring molecule with 4 pyrrole ring.
    Single Fe2+ ion at centre of each pyrrole ring.
    Without iron ring – Porphyrin Ring.
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12
Q

Hemoglobin function?

A
  1. Delivery of oxygen from the lungs to the tissues
  2. Transport of CO2 and protons from tissue to lungs for expiration and excretion
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13
Q

How does Hb work?

A
  1. One molecule of hb will bind to 4 molecules of O2
  2. Cooperative binding of O2 to hb: binding of O2 to one heme increases the binding of O2 to other heme
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14
Q

Bohr effect of hemoglobin?

A
  1. Haemoglobin’s lower affinity for oxygen secondary to increases in partial pressure of carbon dioxide and/or decreased blood pH.
  2. This lower affinity, in turn, enhances the unloading of oxygen into tissues to meet the oxygen demand of the tissue.
  3. It causes shift in the O2 dissociation curve to the right
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15
Q

Describe the oxyhemoglobin dissociation curve?

A
  1. right shift
    - increase pCO2, H+, temp, DPG, decrease pH, sulf-Hb, HbSS > decrease O2 affinity so increase O2 unloading
  2. left shift
    - decrease pCO2, H+, temp, DPG, increase pH, decrease phosphate, met-Hb, CO-Hb, fetal-Hb > increase O2 affinity sp decrease O2 unloading
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16
Q

What is globin switch?

A
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17
Q

Fate of the RBC?

A
  • RBCs normally circulate an average of 120days before being destroyed
  • Once the red cell membrane becomes fragile, the cell ruptures
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18
Q

Where do RBCs self destruct?

A
  • Many of the red cells self destruct in the spleen
  • Squeeze through the red pulp
    > Space between the structural trabeculae are only 3 umeters wide, in comparison with the 8-umeter diameter of the red cell
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19
Q

What are the products released when the RBC is destroyed?
What happens to them?

A

when RBC is destroyed in the spleen hemoglobin is released which in turn breaks down into
1. iron + apoferritin > ferritin > stored and reused
2. globin > protein pool > stored and reused
3. porphyrin > bilirubin > excreted

20
Q

What is anemia?

A

Reduction in red blood cell mass or blood hemoglobin concentration”
- Hemoglobin level too low to meet cellular oxygen demands.

21
Q

Physiology of anemia?

A
  1. Decreased production
  2. Increased destruction
  3. Loss
    - In the normal functioning Bone marrow, anemia results in erythroid hyperplasia which can increase RBC production
22
Q

Epidemiology of anemia?

A
  • Most common hematological disorder in childhood
  • Iron deficiency- the most common cause of anemia in pediatric age worldwide
  • Prevalence of anemia among children 6-59months in Malawi is 55%
23
Q

Epidemiology of anemia is influenced by?

A

age, race, Tanner stage, altitude, genetics

24
Q

Normal Hgb concentration parameters?

A
  • starts high at birth (mean 18.5)
  • declines to its nadir at 2 months (mean 11.5, Lower limit of normal 9.0)
  • rises again to adult values around age 12 (mean 14 female, 14.5 male).
25
Q

Compare Hgb between men and women?

A

Women run about 1 g/dL less than men.

26
Q

MCV normal parameters?

A
  • starts high at birth (mean 108)
  • declines to its nadir at 6-24 months (mean 78, lower limit of normal 70)
  • and rises again to mean 85 around age 12, and to adult values around age 18 (mean 90, lower limit of normal 80
27
Q

Physiologic adaptation to anemia?

A
  1. increased heart rate
  2. increased stroke volume
  3. vasodilation
  4. Decreased oxygen affinity (right shift in oxygen dissociation curve) leading to enhanced 02 delivery to tissues
  5. Elevated 2,3‐BPG (2,3‐DPG)
  6. Bohr effect (↓pH, ↑temp.)
28
Q

Anemia history?

A

Age of onset
Duration
Birth Weight and Gestational age
Milk intake
Solid diet
Feeding problems
Symptoms attributable to anemia
Symptoms of hemolysis
History of blood loss or bruising
Blood transfusions indicate severity or chronicity
Any other symptoms: symptoms of chronic GI, liver or kidney disease
Family history
Drugs and toxins

29
Q

Anemia examination?

A

Dysmorphic features – Bone marrow failure syndrome
Jaundice -Hemolysis
Tongue (atrophy of papillae) –severe Iron deficiency
Purpura or bleeding -Thrombocytopenia
Koilonychia –severe Iron deficiency
Cardiac examination –Heart Failure
Lymphadenopathy –leukemia, lymphoma
Splenomegaly –Hemolysis, leukemia, lymphoma

30
Q

Anemia investigations?

A

FBC (Hb, Hematocrit, MCV, MCH, MCHC, Platelets, RDW)
Peripheral Blood Film (microcytic, normocytic, macrocytic)
Reticulocyte count: High (hemolysis), Low (hypoplastic)
ESR,CRP (chronic disease)
Serum Ferritin, Serum Iron (Iron deficiency, chronic inflammation)
Hemoglobin Electrophoresis (Hemoglobinopathies)
Bone Marrow Examination (hypoplasia, leukemia)

31
Q

RBC size morphology?

A

Normocyte normal size (MCV = 75 105 fl)
Microcyte small cells (MCV < 75 fl)
Macrocye large cells ( MCV > 105 fl)

32
Q

RBC shape morphology?

A

Anisocytosis variation in size
Poikilocytosis variation in shapes
Spherocyte small round cell

33
Q

What is microcytic anemia?

A
34
Q

What is normocytic anemia?

A
35
Q

What is macrocytic anemia?

A
36
Q

How is anemia classified?

A
  1. absolute anemia - decrease in red cell volume
  2. relative anemia - increase in plasma volume
37
Q

Classification of absolute anemia?

A
  1. decreased red cell production
  2. increased red cell destruction
  3. blood loss and blood redistribution
38
Q

What is non severe anemia?

A

Young children
(aged<6years)- Hb <9.3g/dl

39
Q

What is severe anemia?

A

All children
Hb<4g/dl

40
Q

Management of non-severe anemia?

A

Begin treatment, unless the child has severe acute malnutrition

TREAT UNDERLYING CAUSE

41
Q

Management of severe anemia?

A

Give blood transfusion as soon as possible
All children Hb<4g/dl
Less severely anemic children (EVF 13-18%, Hb 4-6g/dl) with the following clinical features:
Shock
Impaired consciousness
Heart failure
Deep, labored breathing
Very high malarial parasitemia (>10% of red cell with parasites)

42
Q

Indications for RBC transfusion?

A
43
Q

Dos for RBC transfusion?

A
44
Q

Blood transfusion complications?

A
45
Q
A

MBBS 3: Pediatrics (43 decks)

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