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Pediatrics👶🏻 > Thalassemia > Flashcards

Thalassemia Flashcards

1
Q

Definition

A

Autosomal recessive disorders due to defective globin chain production
Quantitive defect

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2
Q

a thalassemia syndromes

A

˜ Impaired E chain production ˜ Due to deletion of one or more of the 4 a globin genes on chromosome 16

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3
Q

One gene missing p Silent carrier () (a)

A

Asymptomatic

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4
Q

Two gene missing ➡️a thalassemia trait

A
  • Familial microcytic anemia ; commonly mistaken as iron deficiency
  • Normal iron indices
  • Normal Electrophoresis for age.
  • Diagnosed by DNA analysis.
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5
Q

Three genes missing ➡️ Hemoglobin H disease

A
  • Mild to moderate microcytic hemolytic anemia at birth
  • Evidence of chronic hemolysis
  • Electrophoresis shows: Hb H (4b chains).
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6
Q

Four genes missing → Fetal hydropes

A
  • Severe intra uterine anemia and anemic heart failure
  • Resulting in death in-utero or short after birth
  • Electrophoresis shows: Dominant hemoglobin Bart (4 K globin chains )

with complete absence of normal fetal and adult hemoglobin

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7
Q

B-thalassemia syndromes

A

Impaired B chains production Due to mutation of one or more of the 2 F globin genes on chromosome 11

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8
Q

One gene mutation p F thalassemia trait ( Heterozygous F-thalassemia) B- minor

A

•BoB or B+B
Microcytic anemia with no evidence of overt hemolysis

• Differentiated from iron deficiency anemia by S Normal iron indices and Mentzer index <13 S Characteristic hemoglobin electrophoresis:

¿ Hb A 2 up to 3-7% in over 90% of cases.(diagnostic)
Normal (1-3%)
¿ HbF up to 1-3% in only 50% of cases.

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9
Q

Thalassemia intermedia

A
  • Due to a combination of homozygous mild A and B thalassemia
  • Moderate anemia (Hb 7–10 g/dL) doesn’t require regular transfusions
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10
Q

adult HB

A
  • Two alpha

* Two beta

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11
Q

. Hb a2

A

• Two alpha

. Two delta

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12
Q

fetal

A

• Two alpha

Two gama

•

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13
Q

B Thalassemia Major

Pathophysiology

Impaired Bchain production

A

Impaired B chain production➡️⬇️ Production of Hb

Impaired B chain production➡️ Deposition of excess unmatched E chain inside the RBCs → hemolysis➡️anemia

Impaired B chain production➡️ Compensatory production of other Hb containing non Beta chains especially Hb F➡️⬆️ oHbF (⬆️ O 2 affinity)
-anemia +⬆️O2 affinity ➡️➡️ Tissue hypoxia ➡️➡️ Compensatory increased RBCs production ➡️➡️ Medullary hematopoiesis ➡️➡️ Bone marrow expansion (Skeletal changes) +++++ Extra medullary hematopoiesis ➡️➡️ Splenomegaly (s hepatomegaly

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14
Q

Iron overload due to

A
  • Chronic hemolysis.
  • Enhanced iron absorption.
  • Repeated blood transfusion.
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15
Q

thalassemic facies

A

maxilla hyperplasia, flat nasal bridge, frontal bossing

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16
Q

Clinical picture

A

-General features of chronic hemolytic anemia (see before)

  • Manifestations start insidiously after the 6 th month of age when switch from y to B chain production usually normally occur.
  • Classic features: Progressive anemia, jaundice ,thalassemic facies,and organomegaly

Hemosiderosis p Iron deposition in:

17
Q

Hemosiderosis p Iron deposition in: features

A

1-Skin • Bronzed skin

2-Pituitary → Short stature ,Hypogonadism

3- Heart
• Restrictive cardiomyopathy  Dysrhythmias
• Heart failure
4-Liver
• Liver cirrhosis
• Liver cell failure  Hepatitis
5- Pancreas 1. Diabetes mellitus

6-Thyroid and parathyriod → Hypothyroidism ,Hypoparathyriodism

7- Gonads → Hypogonadism • Delayed puberty

18
Q

Complications and causes of death

A
  1. Heart failure
  2. Liver cell failure
  3. Diabetic keto acidosis
  4. Hypersplenism :
    Sx\Pallor, purpura, pyrexia, and organomegaly S CBC: pancytopenia S Bone marrow\marrow hyperplasia , no malignant cells
  5. Frequent blood transfusions carry risk of blood bone infections e.g. HBV, HCV, AIDS, and CMV
19
Q

Investigations

A

a. For anemia → Low Hb% and Ht. value.
b. For chronic hemolysis

  • Unconjugated hyperbilirubinemia
  • Reticulocytosis (commonly <8%)
  • Skull X-ray in children >3 years

“😱Hair on end” appearance

c. For the cause
1- Blood film → hypochromic, microcytic anemia with target cells.
2- Alkaline denaturation (Apt) test p Hb F resist denaturation by alkali
3- Hemoglobin electrophoresis:
• Markedly raised Hb F (80-90%)
• Slightly raised Hb A2
• Absent or near absent Hb A

4- Prenatal diagnosis is possible by chorionic villous sampling (CVS)

d. For diagnosis of iron overload

  • Serum iron and ferritin
  • Cardiac / hepatic MRI*
  • Liver biopsy*
  • Liver iron by Superconducting Quantum Interference Device (SQUID)
20
Q

Chronic transfusion therapy

A

🌺 Indications for initiation of regular red cell transfusions include:
• Hemoglobin level 7 g/dl (on at least 2 measurements)
• Poor growth
• Facial bone changes

🌺 Aim: To keep pre transfusion Hb > 9.5- 10.5 gm/dl
🌺 Dose: 10-15 ml/kg packed RBCs monthly.

🌺 Benefits
• Allow normal growth and activity
• Decreases bone marrow activity ➡️⬇️ skeletal changes.
• Decreases extra medullary hematopoiesis ➡️⬇️ organomegaly.

21
Q

Iron chelation therapy indications

A

🌼 Often deferred until age 3 to 4 years.

🌼 Indications:
• Cumulative transfusion load of 120 ml/kg or greater
• Serum ferritin level persistently >1,000 ng/ml
• Liver iron concentration .5–7 mg/g dry weight

22
Q

. Drugs used chelation

A

A. Desferroxamine (Desferal)

  • Dose: 25-50 mg/kg/day
  • Route: IV or by continuous SC pump for 10 hours, 5-6 nights per week.
  • Side effect: anaphylaxis, deafness, cataract, retinal damage , yerssinia sepsis and skeletal changes
  • Ascorbic acid 200 mg daily enhance the chelating effect of Desferal

B. Recent Oral drugs

  1. Deferiprone (Ferriprox)
  • Dose : 75-100 mg/kg
  • Value: Effective in Reducing cardiac iron overload.
  • Side effects: Gastric upset ,neutropenia and agranylocytosis
  1. Defrasirox (Exjade)
  • As effective as desferal but oral with longer half life
  • Once daily, 20-40 mg /kg
  • Monitoring of liver enzymes and serum creatinine is essential
23
Q

Supportive treatment

A

Low iron diet
Folic acid 1mg/day
Endorcine support as necessary. Hepatitis A and B vaccine
_ vit c+D

24
Q

Splenectomy

A

y Indications

A. Hypersplenism suggested by:

  • Increasing need for transfusion by u 50% than usual for > 6 months.
  • Annual PRBCs > 250 ml/kg/year in face of uncontrolled iron overload
  • Severe leucopenia and / or thrombocytopenia (Pancytopenia)

B. Huge spleen with pain or pressure symptoms.

y When: Preferably after the 5 th – 6 th year y Risk: Overwhelming sepsis (especially if done < 5 years) y Precautions: See before

25
Q
  1. Other lines of treatment
A

— Hydroxyurea → Induction of Hb F → ⬇️Unmatched a chain accumulation → ⬇️ hemolysis (of limited value due to serious side effects).

— 😶Stem cell transplantation → best for patient less than 17 years —
😁Gene therapy is under research
6. Genetic counseling

Pediatrics👶🏻 (55 decks)

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