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Internal medicine > Red blood cell disorders > Flashcards

Red blood cell disorders Flashcards

1
Q

What is the pathophysiology of porphyrias?

A

Defective enzyme activity in heme biosynthesis resulting in an accumulation of intermediates of heme production that deposit into different tissues

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2
Q

How do you classify porphyrias?

A 
Primary
- acute hepatic
- chronic hepatic
Secondary
- anemia
- alcohol
- heavy metal poisoning
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3
Q

What is the most common porphyria?

A

Porphyria cutanea tarda

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4
Q

What is the peak incidence of porphyria cutanea tarda?

A

30-50yo

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5
Q

What is the pathophysiology of porphyria cutanea tarda?

A

Reduced activity of the uroporphyrinogen III decarboxylase enzyme -> uroporphyrin accumulation in the skin

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6
Q

What are the types of porphyria cutanea tarda?

A 
Type I (sporadic)
Type II (AD)
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7
Q

Name susceptibility factors for porphyria cutanea tarda

A 
Iron overload
Alcohol
Smoking
Hepatitis C
Estrogen therapy
Sunlight exposure
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8
Q

Name the clinical features of porphyria cutanea tarda

A 
Blistering photosensitivity
Hypertrichosis
Hyperpigmentation
Scarring
Milia 
Tea coloured urine
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9
Q

How do you confirm the diagnosis of porphyria cutanea tarda?

A

Urine sample

Serum porphyrins

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10
Q

Discuss the management of porphyria cutanea tarda

A 
General
- avoid susceptibility factors
- phlebotomy
Pharmacological
- low dose hydroxychloroquine
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11
Q

What is the peak incidence of acute intermittent porphyria?

A

20-30yo

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12
Q

Which sex does acute intermittent porphyria predominantly affect?

A

Females > males

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13
Q

What is the pathophysiology of acute intermittent porphyria

A

Porphobilinogen deaminase mutation resulting in porphobilinogen and ALA accumulation

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14
Q

What is the inheritance pattern of acute intermittent porphyria?

A

Autosomal dominant

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15
Q

Name triggers of acute intermittent porphyria attacks

A

Medications
Alcohol
Smoking
Fasting

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16
Q

Which medications trigger acute intermittent porphyria attacks?

A 
CYP450 inducers
Anticonvulsants
Sulfonamides
Anesthetics
Hormone therapy
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17
Q

What are the clinical features of acute intermittent porphyria?

A 
GIT
- severe abdominal pain
- nausea
- vomiting
Neurological
- non-specific pain
- weakness
- paresthesia
- paresis
Autonomic
- tachycardia
- hypertension
Psychiatric
- hallucinations
- disorientation
- anxiety
- insomnia
Red-purple urine
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18
Q

How do you confirm the diagnosis of acute intermittent porphyria?

A

Spot urine sample

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19
Q

How do you manage acute intermittent porphyria?

A 
Acute
- hemin therapy
- glucose loading
Long-term
- Avoid triggers
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20
Q

Why is glucose loading performed in acute intermittent porphyria?

A

Glucose decreases heme synthesis and the excretion of heme precursors

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21
Q

What is a differential diagnosis for acute intermittent porphyria?

A

Lead poisoning

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22
Q

What is the definition of anemia?

A

A decrease in the absolute number of circulating RBCs

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23
Q

What is the WHO criteria for anemia?

A

Men: Hb<13.5g/dL
Women: Hb<12g/dL

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24
Q

How can you classify anemia?

A 
Pathophysiological
Morphological
- microcytic
- normocytic
- macrocytic
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25
Q

Which MCV values determine the morphological classification of an anemia?

A

Microcytic <80
Normocytic 80-100
Macrocytic >100

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26
Q

What is the mechanism of microcytic anemia?

A

Insufficient Hb production

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27
Q

What is the mechanism of normocytic anemia?

A

Decreased blood volume

Decreased erythropoesis

28
Q

What is the mechanism of macrocytic anemia?

A

Defective DNA synthesis

Defective DNA repair

29
Q

Name causes of a microcytic anemia

A 
Defective heme synthesis
- iron deficiency
- lead poisoning
- chronic disease
- sideroblastic
Defective globin chain
- thalassemia
30
Q

Name causes of a normocytic anemia

A 
Hemolytic anemias
Intrinsic defects
1. Hemoglobinopathies
- sickle cell anemia
- HbC disease
2. Enzyme deficiencies
- G6PD deficiency
- pyruvate kinase deficiency
3. Membrane defects
- PNH
- hereditary spherocytosis
- hereditary elliptocytosis
Extrinsic defects
- autoimmune HA
- microangiopathic HA
- macroangiopathic HA
- infections
- mechanical destruction

Non-hemolytic anemias

  • blood loss
  • aplastic anemia
  • chronic kidney disease
31
Q

Name causes of a macrocytic anemia

A 
Megaloblastic
- B12 deficiency
- folate deficiency
- medications
- Fanconi anemia
- orotic aciduria
Non-megaloblastic
- liver disease
- alcohol use
- myelodysplastic anemia
- multiple myeloma
- hypothyroidism
32
Q

Which medications can cause megaloblastic anemia?

A 
Phenytoin
Sulfa drugs
Trimethoprim
Hydroxyurea
MTX
6-mercaptopurine
33
Q

Name the clinical features of anemia

A 
Pallor
Exertional dyspnea
Fatigue
Pica
Worsening angina pectoris
Hyperdynamic state
Extramedullary haematopoesis
34
Q

What are signs of extramedullary haematopoesis?

A

Paravertebral mass

Skull diploic space widening

35
Q

What are laboratory signs of hemolysis?

A

Decr haptoglobin
Incr LDH
Incr indirect bilirubin

36
Q

How do you differentiate between folic acid deficiency and vitamin B12 deficiency using bloods?

A

B12 - incr methylmalonic acid

Folic acid - normal methymalonic acid

37
Q

How do you treat anemia?

A

Treat underlying cause
Blood transfusion
Bone marrow transplant

38
Q

What is aplastic anemia?

A

A pancytopenia caused by bone marrow insufficiency

39
Q

Name causes of aplastic anemia

A 
Acute hepatitis
Medication
Toxins
Ionizing radiation
Viruses
Fanconi's anemia
40
Q

Which medications can cause aplastic anemia?

A 
Carbamazepine
Methimazole
NSAIDs
Chloramphenicol
Sulfa drugs
Antimetabolites
41
Q

Which viruses can cause aplastic anemia?

A 
Parvovirus B19
CMV
HBV
HIV
EBV
42
Q

What is Fanconi’s anemia?

A

Bone marrow failure resulting in pancytopenia and normo/macrocytic anemia due to a DNA crosslink repair defect

43
Q

What is the inheritance pattern of Fanconi’s anemia?

A

Autosomal recessive

44
Q

What disease are patient’s with Fanconi’s anemia prone to developing?

A

Acute myeloid leukemia

Myelodysplastic syndromes

45
Q

Name the clinical features of aplastic anemia

A 
Pallor
Fatigue
Malaise
Petechiae
Purpura
Mucosal bleeding
Infection
46
Q

How do you diagnose an aplastic anemia?

A 
Pancytopenia
Normo/macrocytic anemia
Low reticulocyte count
High EPO
Dry bone marrow tap
47
Q

Discuss the treatment of aplastic anemia

A 
Treat the underlying cause
Supportive
- infection treatment
- blood transfusion
- platelet transfusion
BM stimulants
Immunosuppressants
Haematopoetic cell transplant
48
Q

What is the pathophysiology of anemia of chronic disease?

A

Inflammation

  • reduced iron release from macrophages
  • reduced iron intestinal absorption
  • reduced EPO response
  • reduced erythrocyte survival
49
Q

How do you distinguish between anemia of chronic disease and iron deficiency anemia?

A

Chronic disease = high ferritin

Iron deficiency = low ferritin

50
Q

Discuss the treatment of anemia of chronic disease

A

Treat the underlying cause
Blood transfusion
EPO

51
Q

Define sideroblastic anemia

A

Defective heme metabolism -> iron trapped in mitochondria

52
Q

What is the inheritance pattern of sideroblastic anemia?

A

X linked

53
Q

What are the causes of sideroblastic anemia?

A 
Inherited
Acquired
- B6 deficiency
- lead poisoning
- alcohol use
- drugs 
- copper deficiency
- myelodysplastic syndromes
54
Q

How can you confirm sideroblastic anemia?

A

High iron

Prussian blue BM staining

55
Q

What is pure red cell aplasia?

A

Normocytic, normochromic anemia characterized by a severe reduction in circulating reticulocytes and marked reduction or absence of erythroid precursors in the bone marrow

56
Q

What is the pathophysiology of pure red cell aplasia?

A

Abnormal T-cell function and IgG antibodies that target erythroblasts and erythropoietin

57
Q

Name causes of pure red cell aplasia

A 
Acquired
- idiopathic
- thymoma
- myelodysplastic syndrome
- drugs
- parvovirus B19
- AI disorders
Congenital 
- Diamond-Blackfan anemia
58
Q

How do you confirm the diagnosis of pure red cell aplasia?

A

Low reticulocyte count

BM - absent erythroid precursors

59
Q

Discuss your treatment of pure red cell aplasia

A

Treatment of the underlying cause
RBC transfusions
Immunosuppressants
Cytotoxic agents

60
Q

What is polycythaemia vera?

A

A chronic myeloproliferative neoplasm that is characterized by an erythropoietin-independent, irreversible increase in erythrocyte, granulocyte, and platelet counts

61
Q

Which gene is commonly mutated in polycythaemia vera?

A

JAK2

62
Q

What are the clinical features of polycythaemia vera?

A 
Plethora
Hyperviscosity syndrome
Aquagenic pruritis
Hypertension
Splenomegaly
63
Q

What are the laboratory findings in polycythaemia vera?

A 
↑ Hb/Hct, ↑ RBCs
↑ Platelets (> 450,000/μL)
↑ Leukocytes (> 12,000/μL)
↓ Serum iron levels
↓ ESR
↓ EPO
Arterial O2 saturation: normal
64
Q

What is the diagnostic criteria for polycythaemia vera?

A

3 major/2major + 1 minor

Major

  1. Increased RBCs
  2. BM biopsy showing hypercellularity with trilineage growth
  3. JAK2 gene mutation

Minor
- Decr EPO

65
Q

Give a differential diagnosis for polycythaemia vera

A 
Severe dehydration
Stress erythrocytosis
Chronic hypoxia
High altitude exposure
Paraneoplastic syndrome
Polycystic kidney disease
66
Q

Discuss the management of polycythaemia vera

A

Phlebotomy
Antiplatelet therapy
Cytoreductive therapy

67
Q

Name complications of polycythaemia vera

A 
Thrombotic
- DVT
- stroke
- MI
Hematological
- petechiae
- epistaxis
- bleeding gums
Late stage
- acute myeloid leukemia
- myelodysplastic syndrome
- myelofibrosis

Internal medicine (16 decks)

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