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Thalassemia

Thalassemia is a hereditary cause of microcytic hypochromic anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types and results from a deficiency in either the α or β globin chains, resulting in hemoglobinopathy. The presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor of thalassemia depends on the number of defective chains present and can range from being asymptomatic to rendering the more severely affected patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship to be transfusion dependent. The diagnosis can be confirmed using hemoglobin electrophoresis Electrophoresis An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current. Blotting Techniques, which will reveal the presence of abnormal α- or β-globin chains.

Last updated: Oct 8, 2021

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Disease characteristics

  • Thalassemias are hereditary hemoglobin ( Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange) disorders of α- or β-globin genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure. Defects in these genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure lead to abnormal hemoglobin and RBC structure and function.
  • Presents as microcytic hypochromic anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types:
    • Mild cases can be asymptomatic.
    • Severe cases may lead to splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly, hemolysis, and skeletal abnormalities.

Epidemiology

  • Worldwide prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency
    • α-Thalassemia: 5%; most common in Africa and Asia ASIA Spinal Cord Injuries
    • β-Thalassemia: 3%; most common in the Mediterranean
  • Equal incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency in men and women

Etiology

  • Autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance disorder
  • α-Thalassemia: 2 α genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure (HbA1 and HbA2) = 4 alleles (αα/αα)
    • Chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 16: deletion error Error Refers to any act of commission (doing something wrong) or omission (failing to do something right) that exposes patients to potentially hazardous situations. Disclosure of Information
    • 4 types of disease variations:
      • Minima: deletion of 1 α gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics
      • Minor: deletion of 2 α genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure (same chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics = cis CIS Multiple Sclerosis, opposite chromosomes Chromosomes In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. DNA Types and Structure = trans)
      • HbH disease: deletion of 3 α genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure
      • Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange Barts: deletion of 4 α genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure 
  • β-Thalassemia: 1 β gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics (HbB) = 2 alleles
    • Chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 11
      • Splicing mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations+: decreased expression) or
      • Nonsense mutation Nonsense mutation Types of Mutations0: absent expression)
    • 2 types of disease variations:
      • Thalassemia minor: heterozygous, approximately 50% decreased synthesis Synthesis Polymerase Chain Reaction (PCR)
      • Thalassemia major: homozygous, no production of β globulin, increase in HbA₂(α₂δ₂) and HbF(α₂γ₂), no HbA
Table: Etiology of α-thalassemia
Number of genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure deleted/ genotype Genotype The genetic constitution of the individual, comprising the alleles present at each genetic locus. Basic Terms of Genetics Disease Outcome
1
(αα/α-)
α-Thalassemia minima Silent carrier Carrier Vaccination
2
(α-/α-; trans)
(αα/–; cis CIS Multiple Sclerosis)
α-Thalassemia minor
  • Trait (2=Trait)
  • Mild anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
  • Cis CIS Multiple Sclerosis; worsens with generations
3
(α-/–)
HbH (4 β chains) Moderate-to-severe anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
4
(–/–)
Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange Barts (4 γ chains) Hydrops Hydrops Cholecystitis fetalis (incompatible with life)
Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange: hemoglobin
Table: Etiology of β-thalassemia
Number of genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure deleted/ genotype Genotype The genetic constitution of the individual, comprising the alleles present at each genetic locus. Basic Terms of Genetics Disease Outcome
β0/β or β+/β Thalassemia minor Asymptomatic (mild)
β0/β0 or β+/β+ Thalassemia major (Cooley’s anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types) Transfusion dependent

Pathophysiology

  • Defective Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange formation: leads to Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies that damages RBC membranes
  • Damaged RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology undergo hemolysis, resulting in: 
    • Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
    • Pigmented gallstones Gallstones Cholelithiasis (gallstones) is the presence of stones in the gallbladder. Most gallstones are cholesterol stones, while the rest are composed of bilirubin (pigment stones) and other mixed components. Patients are commonly asymptomatic but may present with biliary colic (intermittent pain in the right upper quadrant). Cholelithiasis
  • Ineffective erythropoiesis Erythropoiesis The production of red blood cells (erythrocytes). In humans, erythrocytes are produced by the yolk sac in the first trimester; by the liver in the second trimester; by the bone marrow in the third trimester and after birth. In normal individuals, the erythrocyte count in the peripheral blood remains relatively constant implying a balance between the rate of erythrocyte production and rate of destruction. Erythrocytes: Histology (due to lack of normal Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange components) leads to: 
    • Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types → high-output heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR)
    • Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis expansion
    • Extramedullary hematopoiesis Extramedullary Hematopoiesis Primary Myelofibrosis → hepatomegaly and/or splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly
  • Iron overload Iron overload An excessive accumulation of iron in the body due to a greater than normal absorption of iron from the gastrointestinal tract or from parenteral injection. This may arise from idiopathic hemochromatosis, excessive iron intake, chronic alcoholism, certain types of refractory anemia, or transfusional hemosiderosis. Hereditary Hemochromatosis (from multiple transfusions to account for damaged native RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology)
    • Compensatory increase in the GI uptake of iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements
    • Endocrinopathies

Clinical Presentation

Table: Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor based on variant
Disease Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor
α-Thalassemia minima Asymptomatic
α-Thalassemia minor
  • Incidental finding
  • Mild hypochromic microcytic anemia Microcytic anemia Conditions in which there is a generalized increase in the iron stores of body tissues, particularly of liver and the mononuclear phagocyte system, without demonstrable tissue damage. The name refers to the presence of stainable iron in the tissue in the form of hemosiderin. Anemia: Overview and Types
  • Offspring with HbH
HbH disease
  • Severe anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types (from birth)
  • Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis expansion
    • Frontal bossing Frontal Bossing Hydrocephalus in Children
    • Chipmunk facies
    • Fragility fractures Fragility fractures Pelvic fractures are a disruption in the cortex of a pelvic bone involving iliac wing fractures, acetabular fractures, or those causing loss of integrity of the pelvic ring (the sacrum and the 2 innominate bones). Patients often present with a history of trauma or a fall, limb length discrepancy, intense pain on palpation, and mechanical instability. Pelvic Fractures
  • Transfusion dependent: leads to iron overload Iron overload An excessive accumulation of iron in the body due to a greater than normal absorption of iron from the gastrointestinal tract or from parenteral injection. This may arise from idiopathic hemochromatosis, excessive iron intake, chronic alcoholism, certain types of refractory anemia, or transfusional hemosiderosis. Hereditary Hemochromatosis
Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange Barts
β-Thalassemia minor
  • Incidental finding
  • Hypochromic microcytic anemia Microcytic anemia Conditions in which there is a generalized increase in the iron stores of body tissues, particularly of liver and the mononuclear phagocyte system, without demonstrable tissue damage. The name refers to the presence of stainable iron in the tissue in the form of hemosiderin. Anemia: Overview and Types
  • Palpable spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: Anatomy (rare)
β-Thalassemia major (Cooley’s anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types)
  • Severe anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types (approximately 6 months of age)
  • Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis expansion
    • Frontal bossing Frontal Bossing Hydrocephalus in Children
    • Chipmunk facies
    • Fragility fractures Fragility fractures Pelvic fractures are a disruption in the cortex of a pelvic bone involving iliac wing fractures, acetabular fractures, or those causing loss of integrity of the pelvic ring (the sacrum and the 2 innominate bones). Patients often present with a history of trauma or a fall, limb length discrepancy, intense pain on palpation, and mechanical instability. Pelvic Fractures
  • Transfusion dependent: leads to iron overload Iron overload An excessive accumulation of iron in the body due to a greater than normal absorption of iron from the gastrointestinal tract or from parenteral injection. This may arise from idiopathic hemochromatosis, excessive iron intake, chronic alcoholism, certain types of refractory anemia, or transfusional hemosiderosis. Hereditary Hemochromatosis
Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange: hemoglobin
Frontal bossing due to excessive need for hematopoiesis

Frontal bossing Frontal Bossing Hydrocephalus in Children due to excessive need for hematopoiesis Hematopoiesis The development and formation of various types of blood cells. Hematopoiesis can take place in the bone marrow (medullary) or outside the bone marrow (extramedullary hematopoiesis). Bone Marrow: Composition and Hematopoiesis

Image: “ Frontal bossing Frontal Bossing Hydrocephalus in Children (abnormally enlarged forehead Forehead The part of the face above the eyes. Melasma) in a child” by National Human Genome Genome The complete genetic complement contained in the DNA of a set of chromosomes in a human. The length of the human genome is about 3 billion base pairs. Basic Terms of Genetics Research Research Critical and exhaustive investigation or experimentation, having for its aim the discovery of new facts and their correct interpretation, the revision of accepted conclusions, theories, or laws in the light of newly discovered facts, or the practical application of such new or revised conclusions, theories, or laws. Conflict of Interest Institute (NIH). License: Public Domain

Diagnosis

Initial studies

  • Take a full medical and family history Family History Adult Health Maintenance (screen in high-risk areas).
  • Order CBC with erythrocyte indices and peripheral blood smear Peripheral Blood Smear Anemia: Overview and Types.
  • On CBC:
    • Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange → usually < 11 g/dL or < 6 g/dL in Cooley’s anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
    • MCV → microcytic (< 70 fL) in thalassemias
    • MCH → low in thalassemias
    • Red-cell distribution width → not very useful in thalassemias (can be normal or elevated)
  • On peripheral blood smear Peripheral Blood Smear Anemia: Overview and Types:
    • Target cells (most common)
    • Howell-Jolly body: blue spot in RBC ( DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure remnant)
    • Anisocytosis: RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology of unequal size
    • Inclusion bodies: seen only in hemoglobin H (HbH) disease (4 β aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies)
    • Heinz bodies Heinz bodies Abnormal intracellular inclusions, composed of denatured hemoglobin, found on the membrane of red blood cells. They are seen in thalassemias, enzymopathies, hemoglobinopathies, and after splenectomy. Asplenia: red spot at the periphery of RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology (denatured Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange)
    • Basophilic stippling
    • To recall the features seen on a peripheral blood smear Peripheral Blood Smear Anemia: Overview and Types of a patient with thalassemia, remember the mnemonic THAL:
      • Target cells (most common)
      • Howell-Jolly body
      • Anisocytosis
      • Low MCH, MCV, and Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange
  • If hemolysis is suspected, order LDH LDH Osteosarcoma:
    • If LDH LDH Osteosarcoma is elevated and hemolysis is suspected, order a reticulocyte Reticulocyte Immature erythrocytes. In humans, these are erythroid cells that have just undergone extrusion of their cell nucleus. They still contain some organelles that gradually decrease in number as the cells mature. Ribosomes are last to disappear. Certain staining techniques cause components of the ribosomes to precipitate into characteristic ‘reticulum’ (not the same as the endoplasmic reticulum), hence the name reticulocytes. Erythrocytes: Histology count: elevated in HbH disease.
  • Order iron studies Iron Studies Iron Deficiency Anemia: normal in thalassemias, abnormal in other causes of anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
Peripheral smear microcytic, hypochromia anemia

Peripheral Smear: microcytic hypochromic anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types with target cells (bull’s eye); anisocytosis (unequal-sized RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology) is also seen

Image: “Target cells (Codocytes, Leptocytes or Mexican hat cells)” by Prof. Osaro Erhabor. License: CC0 1.0

Confirmatory studies

  • If iron studies Iron Studies Iron Deficiency Anemia are normal, order Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange electrophoresis Electrophoresis An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current. Blotting Techniques.
  • Normal Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange electrophoresis Electrophoresis An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current. Blotting Techniques studies show:
    • HbA: 95%
    • HbA2: 3%–5%
    • HbF: minimal amount
    • No HbH or Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange Barts with normal Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange electrophoresis Electrophoresis An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current. Blotting Techniques
  • In α-thalassemia:
    • Minima: normal percentage of HbA and HbA2
    • Minor (trait): normal percentage of HbA and HbA2, but CBC shows anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
    • HbH disease: β-tetrad (i.e., Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange electrophoresis Electrophoresis An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current. Blotting Techniques will show only a β band)
    • Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange Barts: γ-tetrad (i.e., Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange electrophoresis Electrophoresis An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current. Blotting Techniques will show only a γ band)
  • In β-thalassemia
    • Minor: 
      • ↓ HbA (93%)
      • ↑ HbA₂ (5%)
      • ↑ HbF (2%)
    • Major: 
      • No HbA
      • ↑ HbF (90%)
      • ↑ HbA₂ (10%)
  • Other ancillary studies:
    • X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests will show osteopenia Osteopenia Osteoporosis and skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy with “hair on end” appearance.
    • An echocardiogram Echocardiogram Transposition of the Great Vessels may show a reduction in the left ventricular ejection Ventricular ejection Cardiac Cycle fraction.

Management

Minor α- and β-thalassemia

  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are usually asymptomatic and no chronic therapy is indicated.
  • Periodic folate Folate Folate and vitamin B12 are 2 of the most clinically important water-soluble vitamins. Deficiencies can present with megaloblastic anemia, GI symptoms, neuropsychiatric symptoms, and adverse pregnancy complications, including neural tube defects. Folate and Vitamin B12 supplementation may be helpful during physiologic stress (e.g., pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care).
  • Provide genetic counseling Genetic Counseling An educational process that provides information and advice to individuals or families about a genetic condition that may affect them. The purpose is to help individuals make informed decisions about marriage, reproduction, and other health management issues based on information about the genetic disease, the available diagnostic tests, and management programs. Psychosocial support is usually offered. Myotonic Dystrophies regarding risk to the offspring.

Cooley’s anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types and HbH disease

  • Transfusions: 
    • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are transfusion dependent.
    • Target Hb Hb The oxygen-carrying proteins of erythrocytes. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. Gas Exchange level > 10 g/dL
    • Folate Folate Folate and vitamin B12 are 2 of the most clinically important water-soluble vitamins. Deficiencies can present with megaloblastic anemia, GI symptoms, neuropsychiatric symptoms, and adverse pregnancy complications, including neural tube defects. Folate and Vitamin B12 supplementation, if not transfused
  • Splenectomy Splenectomy Surgical procedure involving either partial or entire removal of the spleen. Rupture of the Spleen and cholecystectomy Cholecystectomy Cholecystectomy is a surgical procedure performed with the goal of resecting and extracting the gallbladder. It is one of the most common abdominal surgeries performed in the Western world. Cholecystectomy is performed for symptomatic cholelithiasis, cholecystitis, gallbladder polyps > 0.5 cm, porcelain gallbladder, choledocholithiasis and gallstone pancreatitis, and rarely, for gallbladder cancer. Cholecystectomy
    • Splenectomies reduce transfusion requirements.
    • Post-splenectomy vaccinations ( encapsulated Encapsulated Klebsiella organisms)
      • Pneumococcal polyvalent
      • Haemophilus influenzae Haemophilus Influenzae A species of Haemophilus found on the mucous membranes of humans and a variety of animals. The species is further divided into biotypes I through viii. Haemophilus type b
      • Pneumococcal conjugate
    • Cholecystectomy Cholecystectomy Cholecystectomy is a surgical procedure performed with the goal of resecting and extracting the gallbladder. It is one of the most common abdominal surgeries performed in the Western world. Cholecystectomy is performed for symptomatic cholelithiasis, cholecystitis, gallbladder polyps > 0.5 cm, porcelain gallbladder, choledocholithiasis and gallstone pancreatitis, and rarely, for gallbladder cancer. Cholecystectomy to prevent recurrent gallstones Gallstones Cholelithiasis (gallstones) is the presence of stones in the gallbladder. Most gallstones are cholesterol stones, while the rest are composed of bilirubin (pigment stones) and other mixed components. Patients are commonly asymptomatic but may present with biliary colic (intermittent pain in the right upper quadrant). Cholelithiasis
  • Iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements chelation:
    • Reduces serum iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements levels
    • Deferoxamine Deferoxamine Natural product isolated from streptomyces pilosus. It forms iron complexes and is used as a chelating agent, particularly in the mesylate form. Hereditary Hemochromatosis (IV)
    • Deferiprone Deferiprone A pyridone derivative and iron chelator that is used in the treatment of iron overload in patients with thalassemia. Hereditary Hemochromatosis/ deferasirox Deferasirox A triazole and benzoate derivative that acts as a selective iron chelator. It is used in the management of chronic iron overload due to blood transfusion or non-transfusion dependent thalassemia. Hereditary Hemochromatosis (oral formulations)
  • Endocrine therapy:
    • Administer deficient hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types.
    • Bisphosphonates Bisphosphonates Bisphosphonates are pyrophosphate analogs most well-known for treating osteoporosis by preventing bone loss. Bisphosphonates end in the suffix “-dronate” or “-dronic acid” (e.g., alendronate, risedronate, pamidronate) and bind to hydroxyapatite crystals in bone, inhibiting osteoclast-induced bone resorption. Bisphosphonates to prevent osteopenia Osteopenia Osteoporosis and osteoporosis Osteoporosis Osteoporosis refers to a decrease in bone mass and density leading to an increased number of fractures. There are 2 forms of osteoporosis: primary, which is commonly postmenopausal or senile; and secondary, which is a manifestation of immobilization, underlying medical disorders, or long-term use of certain medications. Osteoporosis
    • Fertility agents
  • Definitive therapy: allogeneic stem cell transplantation Allogeneic Stem Cell Transplantation Acute Lymphoblastic Leukemia 
  • Genetic counseling Genetic Counseling An educational process that provides information and advice to individuals or families about a genetic condition that may affect them. The purpose is to help individuals make informed decisions about marriage, reproduction, and other health management issues based on information about the genetic disease, the available diagnostic tests, and management programs. Psychosocial support is usually offered. Myotonic Dystrophies

Differential Diagnosis

The differential diagnosis includes other conditions associated with microcytic anemia Microcytic anemia Conditions in which there is a generalized increase in the iron stores of body tissues, particularly of liver and the mononuclear phagocyte system, without demonstrable tissue damage. The name refers to the presence of stainable iron in the tissue in the form of hemosiderin. Anemia: Overview and Types or target cells.

  • Iron-deficiency anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types: the other major cause of microcytic hypochromic anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types besides thalassemia. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may present with pallor and easy fatigability. Iron studies Iron Studies Iron Deficiency Anemia are required to obtain the diagnosis. Findings of the iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements study will indicate decreased iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements levels and an increased total iron-binding capacity. Treatment is with oral iron supplementation Iron Supplementation Iron Deficiency Anemia.
  • Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types of chronic disease (“ anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types of chronic inflammation Chronic Inflammation Inflammation”): secondary to inflammatory, infectious Infectious Febrile Infant, or malignant disease. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship present with findings similar to those of iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements deficiency, namely, pallor and easy fatigability. Iron studies Iron Studies Iron Deficiency Anemia will reveal low levels of serum iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements and transferrin Transferrin An iron-binding beta1-globulin that is synthesized in the liver and secreted into the blood. It plays a central role in the transport of iron throughout the circulation. Heme Metabolism; however, ferritin Ferritin Iron-containing proteins that are widely distributed in animals, plants, and microorganisms. Their major function is to store iron in a nontoxic bioavailable form. Each ferritin molecule consists of ferric iron in a hollow protein shell (apoferritins) made of 24 subunits of various sequences depending on the species and tissue types. Hereditary Hemochromatosis levels will be normal or increased. Treatment is targeted toward resolving the underlying chronic disease.
  • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy disease: Target cells can be seen on the peripheral blood smear Peripheral Blood Smear Anemia: Overview and Types of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy disease. These target cells, having a large and targetoid appearance, are formed due to excess membrane lipids Lipids Lipids are a diverse group of hydrophobic organic molecules, which include fats, oils, sterols, and waxes. Fatty Acids and Lipids.
  • Post-splenectomy patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship: Target cells and Howell-Jolly bodies Howell-Jolly Bodies Asplenia appear in the peripheral blood smear Peripheral Blood Smear Anemia: Overview and Types of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship after splenectomy Splenectomy Surgical procedure involving either partial or entire removal of the spleen. Rupture of the Spleen. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may also have a mild-to-marked increase in platelet count (thrombocytosis).

References

  1. Needs T., Gonzalez-Mosquera L.F., Lynch D.T. (2020). Beta Thalassemia. StatPearls. Retrieved July 5, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK531481/
  2. Harewood J., Azevedo A.M. (2020). Alpha Thalassemia. StatPearls. Retrieved July 5, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK441826/
  3. Scordino T. (2016). Target Cells. American Society of Hematology. Morphologic Variants of Normal Cells. https://imagebank.hematology.org/image/60310/target-cells

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