Thalassemia: Difference between revisions

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==Background==
==Background==
*A group of hereditary disorders resulting in microcytic, hypochromic, hemolytic anemia
*A group of hereditary disorders resulting in microcytic, hypochromic, hemolytic [[anemia]]
*Most common in Mediterranean, Middle Eastern, African and Southeast Asian population
*Most common in Mediterranean, Middle Eastern, African and Southeast Asian population


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**β-globin gene mutations cause β-thalassemia; ɑ-globin mutations cause ɑ-thalassema
**β-globin gene mutations cause β-thalassemia; ɑ-globin mutations cause ɑ-thalassema


'''ɑ-Thalassemia Carrier and Trait'''
===ɑ-Thalassemia Carrier and Trait===
*no clinical symptoms or physical findings
*No clinical symptoms or physical findings
*microcytic RBCs and normal Hb level
*Microcytic RBCs and normal Hb level


'''Hemoglobin H Disease (HbH disease)'''
===Hemoglobin H Disease (HbH disease)===
*one ɑ-globin chain gene is still functional
*One ɑ-globin chain gene is still functional
*typically presents in neonatal period with severe hypochromic anemia
*Typically presents in neonatal period with severe hypochromic [[anemia]]
*hypochromic, microcytic anemia with jaundice and hepatosplenomegaly
*Hypochromic, microcytic anemia with [[jaundice]] and [[hepatomegaly|hepatosplenomegaly]]
*may not require regular transfusions
*May not require regular [[pRBCs|transfusions]]
*tranfusions may be necessary in setting of increased oxidative stress or infection which may precipitate hemolysis
*[[pRBCs|Transfusions]] may be necessary in setting of increased oxidative stress or infection which may precipitate [[hemolytic anemia|hemolysis]]
*Note that alpha thalassemia major (Hb Bart) results in [[hydrops fetalis]], and thus is not an adult disease process


'''β-Thalassemia Minor (β-Thalassemia Trait)'''
===β-Thalassemia Minor (β-Thalassemia Trait)===
*heterozygous for β-globin mutation
*Heterozygous for β-globin mutation
*mild microcytic anemia
*Mild microcytic [[anemia]]
*splenomegaly uncommon
*Splenomegaly uncommon
*microcytosis, hypochromia, basophilic stippling on blood smear
*Microcytosis, hypochromia, basophilic stippling on blood smear
*no clinical symptoms
*Co clinical symptoms


'''β-Thalassemia Major (Cooley Anemia)'''
===β-Thalassemia Major (Cooley Anemia)===
*both β-globin genes defective; β-globin chain production severely impaired
*Both β-globin genes defective; β-globin chain production severely impaired
*typically presents >6mos of life (HbF production replaced with β-globin to form HbA)
*Typically presents >6mos of life (HbF production replaced with β-globin to form HbA)
*hepatosplenomegaly, jaundice, expansion of erythroid marrow causing bone changes and osteoporosis, susceptible to infection
*[[hepatomegaly|Hepatosplenomegaly]], [[jaundice]], expansion of erythroid marrow causing bone changes and osteoporosis, susceptible to [[osteomyelitis|infection]]
*severe anemia requiring regular and lifelong blood transfusions
*Severe [[anemia]] requiring regular and lifelong blood [[pRBCs|transfusions]]
**iron overload secondary to frequent transfusions is etiology of most of morbidity and mortality
**[[hemochromatosis|Iron overload]] secondary to frequent transfusions is etiology of most of morbidity and mortality
*low MCV with microcytic and hypochromic RBC
*Low MCV with microcytic and hypochromic RBC


'''Sickle Cell-β-Thalassemia Disease'''
===Sickle Cell-β-Thalassemia Disease===
*gene for sickle Hb is inherited from one parent and gene for β-thalassemia is inherited from the other parent
*Gene for sickle Hb is inherited from one parent and gene for β-thalassemia is inherited from the other parent
*1 per 1600 African American births
*1 per 1600 African American births
*severity depends on type of β-thalassemia gene inherited
*Severity depends on type of β-thalassemia gene inherited
**80-90% inherit β-thalassemia gene that has some normal β-chain production; these patients have mild hemolytic anemia with near-normal Hb levels, few crises
**80-90% inherit β-thalassemia gene that has some normal β-chain production; these patients have mild hemolytic anemia with near-normal Hb levels, few crises
**10-20% inherit β-thalassemia gene that produces no-chains; these patients have severe hemolytic anemia and vaso-occlusive symptoms
**10-20% inherit β-thalassemia gene that produces no-chains; these patients have severe [[hemolytic anemia]] and [[vaso-occlusive crisis|vaso-occlusive symptoms]]


==Differential Diagnosis==
==Differential Diagnosis==
===[[Anemia]]===
===[[Anemia]]===
====RBC Loss====
====RBC Loss====
*Hemorrhage
*[[Hemorrhage]]
====RBC consumption (Destruction/hemolytic)====
====RBC consumption (Destruction/hemolytic)====
*Hereditary  
*Hereditary  
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*Chemicals (e.g. [[ETOH]])
*Chemicals (e.g. [[ETOH]])
*Radiation
*Radiation
*Infection ([[HIV]], parvo)
*Infection ([[HIV]], [[parvovirus B19|parvo]])
====Megaloblastic (macrocytic)====
====Megaloblastic (macrocytic)====
*Vitamin B12/folate deficiency
*Vitamin B12/folate deficiency
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*Identify and discontinue precipitating agent
*Identify and discontinue precipitating agent
*Supportive care  
*Supportive care  
*Blood transfusions for severe anemia
*[[pRBCs|Blood transfusions]] for severe anemia


==Disposition==
==Disposition==

Latest revision as of 18:47, 1 October 2019

Background

  • A group of hereditary disorders resulting in microcytic, hypochromic, hemolytic anemia
  • Most common in Mediterranean, Middle Eastern, African and Southeast Asian population

Clinical Features

  • Categorized depending on globin chain affected or the abnormal Hb produced
    • β-globin gene mutations cause β-thalassemia; ɑ-globin mutations cause ɑ-thalassema

ɑ-Thalassemia Carrier and Trait

  • No clinical symptoms or physical findings
  • Microcytic RBCs and normal Hb level

Hemoglobin H Disease (HbH disease)

  • One ɑ-globin chain gene is still functional
  • Typically presents in neonatal period with severe hypochromic anemia
  • Hypochromic, microcytic anemia with jaundice and hepatosplenomegaly
  • May not require regular transfusions
  • Transfusions may be necessary in setting of increased oxidative stress or infection which may precipitate hemolysis
  • Note that alpha thalassemia major (Hb Bart) results in hydrops fetalis, and thus is not an adult disease process

β-Thalassemia Minor (β-Thalassemia Trait)

  • Heterozygous for β-globin mutation
  • Mild microcytic anemia
  • Splenomegaly uncommon
  • Microcytosis, hypochromia, basophilic stippling on blood smear
  • Co clinical symptoms

β-Thalassemia Major (Cooley Anemia)

  • Both β-globin genes defective; β-globin chain production severely impaired
  • Typically presents >6mos of life (HbF production replaced with β-globin to form HbA)
  • Hepatosplenomegaly, jaundice, expansion of erythroid marrow causing bone changes and osteoporosis, susceptible to infection
  • Severe anemia requiring regular and lifelong blood transfusions
    • Iron overload secondary to frequent transfusions is etiology of most of morbidity and mortality
  • Low MCV with microcytic and hypochromic RBC

Sickle Cell-β-Thalassemia Disease

  • Gene for sickle Hb is inherited from one parent and gene for β-thalassemia is inherited from the other parent
  • 1 per 1600 African American births
  • Severity depends on type of β-thalassemia gene inherited
    • 80-90% inherit β-thalassemia gene that has some normal β-chain production; these patients have mild hemolytic anemia with near-normal Hb levels, few crises
    • 10-20% inherit β-thalassemia gene that produces no-chains; these patients have severe hemolytic anemia and vaso-occlusive symptoms

Differential Diagnosis

Anemia

RBC Loss

RBC consumption (Destruction/hemolytic)

Impaired Production (Hypochromic/microcytic)

  • Iron deficiency
  • Anemia of chronic disease
  • Thalassemia
  • Sideroblastic anemia

Aplastic/myelodysplastic (normocytic)

  • Marrow failure
  • Chemicals (e.g. ETOH)
  • Radiation
  • Infection (HIV, parvo)

Megaloblastic (macrocytic)

  • Vitamin B12/folate deficiency
  • Drugs (chemo)
  • HIV

Evaluation

  • CBC
  • CMP
  • Blood smear
  • Reticulocyte count
  • LDH
  • Haptoglobin

Management

  • Identify and discontinue precipitating agent
  • Supportive care
  • Blood transfusions for severe anemia

Disposition

See Also

External Links

References

  • Tintinalli's Emergency Medicine 7th Edition, pg1486-7
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