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H - pediatrics > Heme > Flashcards

Heme Flashcards

1
Q

Fanconi anemia

A

Aka constitutional aplastic anemia
- physical abn present at birth: thumb/radius anomalies, hyperpigmentation, small size, microcephaly, Rena anomalies (horseshoe, absent, duplicated kidney)
–> aplastic anemia presents around age 5
At risk of leukemia and epithelial carcinomas

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2
Q

Fanconi diagnosis

A

Chromosomal breakage analysis in lymphocytes and molecular diagnosis to confirm and test relatives

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3
Q

Disorders of red cell production in early childhood

A

Transient erythroblastopenia of childhood (TEC)
Diamond-Blackfan anemia

–> both have low Hgb and inappropriately low retic count, and bone marrows may be indistinguishable with reduced/absent erythroid activity

TEC = self limited
D-B = requires lifelong treatment
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4
Q

Diamond blackfan vs TEC diagnosis

A

Age of presentation: DB typically in first 6 months, TEC usually after 1 year
Red cells: DB have fetal characteristics (incr mcv, incr hgb F, presence of i antigen)
Adenosine deaminase: elevated in DB, normal in TEC

Mutations: DB gene for ribosomal protein S19

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5
Q

Wiskott-Aldrich syndrome

A

Eczema, thrombocytopenia, combined B and T cell immunodeficiency
X linked
WAS gene

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6
Q

Evan syndrome

A

Autoimmune hemolytic anemia + ITP

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7
Q

Direct vs. Indirect Coombs test

A

Direct: autoAb or complement on a patients rbcs
Indirect: autoAb in patients serum

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8
Q

Cell membrane defects causes of hemolytic anemia (4)

A
  1. Hereditary spherocytosis (75% AD, 25 AR)
  2. Hereditary eliptocytosis (AD)
    - -> both spectrin defect causing fragility of RBC membrane
  3. Hereditary stomacytosis (incr permeability of rbc membrane to cation, smear shows swollen cup shaped cells with a mouth-like slit –> very rare)
  4. Paroxysmal nocturnal hemoglobinuria (clonal abn with PIGA gene mutation –> abn surface protein anchor –> rbcs susceptible to complement mediated destruction.
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9
Q

Paroxysmal nocturnal hemoglobinuria diagnosis

A

Hemolytic anemia and hemoglobinuria
thrombocytpenia and leukopenia may also be present
** flow cytometry shows absence of CD 59
Hemolysis characteristically worse at night during sleep and morning hemoglobinuria is typical. Hemolysis often precipitated by infection.

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10
Q

Paroxysmal nocturnal hemoglobinuria treatment

A

steroids limit duration of hemolysis

BMT successful in some cases

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11
Q

Hemolytic anemia enzyme defects (2)

A

G6PD: deficiency leads to decreased protection from oxidative stress, hemolytic anemia precipitated by O2stress (e.g. sulfonamides, fava beans, antimalarials, napthalene). X-linked.
2. Pyruvate kinase deficiency: PK deficient RBCs unable to produce ATP, increased 2,3DPG –> rightward shift of O2 dissociation curve. Smear with polychromtophilic RBCs. AR, most common. Splenectomy not currative but may improve anemia.

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12
Q

Normal Hemoglobin types and % in adult

A 
Adult Hb (HbA): 2 alpha, 2 beta chains 95%
Minor adult Hb (HbA2): 2 alpha and 2delta chains
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13
Q

Hemoglobin in Sickle Cell

A

Hb S: single aa substitution (Glu –> Val) in HbA. DeO2 HbS polymerizes to form a spindle-shaped sickle erythrocyte with shortened survival and can obstruct small blood vessels –> distal tissue ischemia and necrosis

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14
Q

Hb S carrier

A

benign course, 30-40% of Hb is Hb S, which isn’t enough to cause sickling. Protective against malaria.

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15
Q

Other sickle cell syndromes (apart from Hb SS)

A

Hb SC: course similar but less severe than Hb SS
HbS B0 thalassemia: course similar to Hb SS
Hb S B+ thalassemia: similar but less severe to Hb SS

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16
Q

Acute complications of sickle cell disease (8!)

A
  1. Pain crisis (hydration, analgesia)
  2. Dactylitis (infarcts of small bones in hands/feet with swelling - usually in infancy)
  3. Sequestration crisis (trapping RBCs in spleen with abrupt fall in Hb)
  4. Acute chest syndrome (vaso-occlusion of pulmonary vessels with fever, new infiltrate on CXR and hypoxia) –> treat with hydration, abx, O2, PPV, transfusion
  5. Aplastic crisis (Parvo B19 causing severe anemia and reticulcytopenia, treat with transfusion)
  6. Stroke and TIAs (acute neuro deficit, 11-20% don’t have acute deficits, early detection with routine annual transcranial doppler (TCD), chronic transfusion therapy
  7. Priapism (vaso-occlusive obstruction of venous drainage of penis, sustained >24 hrs - hydration, analgesia, transfusion, epi, sildenifil, aspiration)
  8. INFECTION!! splenic dysfunction
17
Q

Hb SS common organisms for infection

A

Stept pneumo, H flu, Staph
Splenic dysfunction
ACS >3 years: chlamydia pneumo and mycoplasma - treat with ceftriaxone and macrolide
Osteomyelitis: think about salmonella

18
Q

Chronic complications of sickle cell (5)

A
  1. Gallstones (42% of patients age 15-18)
  2. Pulmonary htn (annual echo after 16)
  3. Renal disease (ACEi for microalbuminuria, hydroxyurea)
  4. Ocular (prolif and nonprolif retinopathy - eye exam starting at 10 years) - retinopathy more common in HbSC than SS
  5. avascular necrosis (from expansion of bone marrow and repeated bone infarction) - painful hip/knee
19
Q

Alpha thalassemias 1-4

A

Alpha chain is determined by 4 identical genes on Chrom 16
1 gene deletion: -, a/ a, a = silent carrier, asymptomatic normal Hb. 1-2% barts Hb on newborn elctrophoresis
2 del: -, a/ -a, or -,-/a,a = alpha-thal trait = asympt with mild anemia, no treatment. 5-10% Barts Hb on NBE
3 del: -,-/-,a = HbH disease (20-30% Bart’s Hb, 5-10% HbH), mod-severe anemia with transfusions, folate +/- splenectomy
4 del: -,-/-,- = hydrops fetalis, fatal 89-90% Barts Hb, no normal Hb.

20
Q

Beta thalassemia mutations

A

defective beta chain, relative excess of alpha chains
beta production controlled by 2 genes on chrom 11 with 2 mutations
1. B0 = absence of beta chain production
2. B+ = decr B chain

21
Q

Beta thal subtypes

A

B0 or B+ heterozygote: trait/minor with elevated HbA2 and HbF, mild anemia asymptomatic
B+ thal: B+/B+ = thal intermedia 70-90% HbF, 2% HbA2, trace A. Moderate anemia at 2 years, req periodic transfusions

B0 thal homozygous: Bthal major = 98% HbF, 2% Hb A2, severe anemia within 6 months, FTT CHF without treatment, transfusion dependent.

22
Q

dexferozmine

A

iron chelation to prevent iron overload in patients requiring chronic transfusions

23
Q

Barts Hb

A 
4 gamma chains
alpha thal (since less alpha chains)
24
Q

Hb H

A

4 beta chains

alpha thal

25
Q

alpha thalassemia diagnosis by electrophoresis

A

only helpful in the newborn period: shows barts Hb instead of HbF (no alpha)!

26
Q

beta thal electrophoresis

A

relative increase in alpha and normal amount of gamma and delta chains leads to increased Hb F (a2gamma2) and Hb H (a2d2)

27
Q

Parvovirus B19 marrow findings

A

nuclear inclusinos in erythoblasts and giant pronomoblasts on light microscopy
cytotoxic to erythroid progenitor cells
transient cessation in erythropoiesis aplastic crisis in those with hemolysis (e.e.g Hb SS, spherocytosis etc.)

28
Q

Parvo B19 in immunodeficient

A

persistent parvovirus infection bc unable to mount response –> severe pure RBC aplasia, often thought to have TEC. No spontaneous recovery, do Parvo PCR (not Ab!), treat with high dose IVIG

29
Q

Congenital Dyserythropoietic anemias

A

ineffective erythropoiesis, and resulting from a decrease in the number of red blood cells (RBCs) in the body and a less than normal quantity of hemoglobin in the blood

3 types, rare.

30
Q

Iron deficiency anemia progression

A
  1. Decreased tissue iron stored (correlates to ferritin in absence of inflammation)
  2. Serum Fe levels decrease, Fe-binding capacity increases (serum transferrin) and saturation decreases (transferrin saturation)
  3. RBCs become smaller and decreased Hb (MCV and MCH)
    –> increased RDW, hypochromic, microcytosis, poikilocytosis
    Absolute retic count shows insufficient response to anemia
    Nucleated RBCs on smear if severe

H - pediatrics (15 decks)

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