Anemia and Hematology Lecture Notes

Flashcards covering the classification, clinical features, diagnostic tests, and treatments for various pediatric anemias as described in the lecture notes.

Hematopoiesis

The process which maintains lifelong production of RBCs, occurring in the liver, yolk sac, spleen, and postnatally in the bone marrow (BM).

Hb F (fetal)

A hemoglobin type composed of 2 $\alpha$ alpha chains and 2 $\gamma$ gamma chains, making up 74% of hemoglobin at birth and 1% in adults.

Hb A (adult)

A hemoglobin type composed of 2 $\alpha$ alpha chains and 2 $\beta$ beta chains, making up 25% of hemoglobin at birth and 97% in adults.

Hb A2

A hemoglobin type composed of 2 $\alpha$ alpha chains and 2 $\delta$ delta chains, making up 1% of hemoglobin at birth and 2% in adults.

Hb H

A hemoglobin type composed of 2 $\beta$ beta chains only.

Hb Barts

A hemoglobin type composed of 2 $\gamma$ gama chains only.

Mentzer's index

Calculated as MCV / RBC's count; it is typically Normal in Thalassemia ($< 13$) and High in IDA ($> 13$).

Target cell

An RBC shape abnormality seen in conditions such as Thalassemia.

Spherocyte

An RBC shape abnormality characteristic of Spherocytosis.

Schistocyte

An RBC shape abnormality associated with Microangiopathic Hemolytic Anemia (MAHA).

Heinz bodies

RBC inclusion bodies typically seen in G6PD deficiency.

Howell Jolly bodies

RBC inclusion bodies characteristic of Sickle Cell Disease (SCD).

Physiological anemia of newborns

Anemia caused by intrauterine hypoxia leading to erythropoietin-induced polycythemia, followed by post-birth oxygenation leading to BM suppression.

Iron Deficiency Anemia (IDA)

The most common anemia in pediatrics, most often caused by nutritional factors, peaking between 6 and 24 months of age.

Koilonychia

Spoon-shaped nails, a clinical sign associated with Iron Deficiency Anemia.

Transferrin

The protein responsible for carrying iron in the blood.

Ferritin

The storage form of iron; its serum level is the most important iron study for diagnosing IDA (low in IDA).

Total iron binding capacity (TIBC)

A laboratory value that is high in patients with Iron Deficiency Anemia.

Megaloblastic anemia (B12 deficiency)

Anemia characterized by macrocytic hyperchromic RBCs and hypersegmented neutrophils, caused by low intake (vegans) or low absorption at the terminal ileum.

Folate deficiency

A form of megaloblastic anemia where stores last 3-4 months and absorption occurs in the small intestine (duodenum and jejunum); can be caused by anticonvulsants like phenytoin.

G6PD deficiency

The most common enzymatic disorder in RBCs; it is an X-linked recessive (XLR) disorder triggered by oxidizing agents like fava beans or certain antibiotics.

Sickle cell anemia (Hb SS)

An autosomal recessive structural defect where valine replaces glutamic acid in the 6th position of the $\beta$ chains.

Hand foot syndrome (dactylitis)

A common vaso-occlusive crisis in children under 2 years old with SCD, presenting as painful swelling of hands and feet.

Acute chest syndrome

A fatal crisis in SCD characterized by sudden SOB, chest pain, cough, fever, respiratory distress (RD), and CXR patches.

Sequestration crisis

A crisis involving the occlusion of venous outflow and acute pooling of blood in the spleen and liver, leading to hypovolemic shock and massive splenomegaly.

Hydroxyurea

A medication used in Sickle Cell Disease and Thalassemia to increase the production of Hb F on a long-term basis.

Hydrops fetalis

The most severe form of $\alpha$-thalassemia involving the loss of all 4 globin genes ($- - / - -$), resulting in severe anemia, anasarca, and heart failure.

Cooley’s anemia

Also known as $\beta$-thalassemia major; the most severe form of thalassemia requiring chronic blood transfusions and monitoring for iron overload.

Hair on end appearance

A characteristic finding on a skull X-ray in patients with $\beta$-thalassemia major due to bone marrow expansion.

Hereditary spherocytosis (HS)

An autosomal dominant intrinsic defect in membrane proteins (spectrin-ankyrin) resulting in less flexible, spherical RBCs that are rapidly removed by the spleen.

Osmotic fragility test

The diagnostic laboratory investigation for Hereditary Spherocytosis.

Warm Autoimmune Hemolytic Anemia (AIHA)

AIHA caused by IgG antibodies active between $35 \text{--} 40^{\circ} \text{C}$, often primary (idiopathic) and diagnostic via a positive Direct Coombs test.

Cold Autoimmune Hemolytic Anemia

AIHA caused by IgM antibodies active at temperatures below $37^{\circ} \text{C}$, which require complement for intravascular hemolysis and cause agglutination in vitro.

Aplastic anemia

Bone marrow failure characterized by pancytopenia (low RBCs, WBCs, and platelets) and a hypoplastic bone marrow with increased fat.

Fanconi anemia

An autosomal recessive inherited form of aplastic anemia presenting at 5-6 years old with short stature, microcephaly, cafe au lait spots, and absent or abnormal thumb-radii.

Schwachman diamond syndrome

An autosomal recessive disorder presenting with bone marrow failure (neutropenia/pancytopenia) and pancreatic exocrine failure (chronic diarrhea).

Diamond-Blackfan syndrome

An autosomal recessive disorder known as pure red cell aplasia, appearing in the first year of life with macrocytic anemia and skeletal triphalangeal thumbs.

Transient erythroblastopenia of childhood

An isolated red cell defect occurring between 6 months and 5 years of age with normal MCV and spontaneous recovery.