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Clin Med - Hematology > Hemoglobinopathies > Flashcards

Hemoglobinopathies Flashcards

1
Q

most common causes of inherited hemoglobin disorders

A

DNA deletions or point mutations

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2
Q

what is a quantitative hemoglobin disorder

A

thalassemia

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3
Q

what is a qualitative hemoglobin disorder

A

hemoglobinopathy

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4
Q

normal fetal hemoglobin made of?

A

2 alpha chains and 2 gamma chains

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5
Q

normal adult hemoglobin made of

A

2 alpha chains and 2 beta chains

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6
Q

in thalassemia what is the balance of alpha and beta chains

A

alpha thalassemia- excess beta

beta thalassemia- excess alpha

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7
Q

pathophysiology of thalassemia

A

excess globins precipitate and damage the RBC membrane, ineffective erythropoiesis

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8
Q

outcomes of thalassemia

A

anemia, bone marrow expansion, extramedullary hematopoiesis, increased intestinal iron absorption

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9
Q

Sickle cell and thalassemia protects from what disease?

A

malaria

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10
Q

silent carrier in thalassemia

A

one deletion of the functional gene

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11
Q

What is alpha-thalassemia trait

A

two deletions of functional genes ( cis- more common in Asian pops or trans more common in African pop)

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12
Q

HbH disease

A

3 deletions of functional genes

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13
Q

hydrops fetalis

A

4 deletions of functional genes- incompatible with life

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14
Q

alpha thalassemia trait definition

A

reduced alpha globin chain synthesis due to 2-gene deletion- causes an excess amount of gamma globin at birth, or beta globin as an adult

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15
Q

best time to identify alpha thalassemia

A

in newborns- excess gamma globin and fast band production makes it more identifiable with testing. For adults, try to track newborn screen.

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16
Q

Heinz bodies

A

detects protein precipitates, denatured proteins. Test is

not commonly used due to common false negatives

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17
Q

treatment for hydrop fetalis

A

if caught in utero- can do transfusion support.

then stem cell transplantation to treat after birth.

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18
Q

beta thalassemia

A

beta-0- producing no beta globin

beta+ produces little beta globin

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19
Q

B-thalassemia major

A

homozygous
severe anemia
requires life-long RBC transfusion

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20
Q

B-thalassemia intermedia

A

mild anemia

occasional transfusions required

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21
Q

B-thalassemia trait

A

heterozygous
asymptomatic
confused with iron deficiency- suspect if patient does not respond to iron therapy

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22
Q

phenotypes for b thalassemia
mild
moderate
severe

A

B+ B+
Bo B+
Bo Bo

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23
Q

beta thalassemia trait under the microscope

A

unbalanced a:b chains
elevated A2
elevated Hb F
microcyctic anemia

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24
Q

treatment of beta thalassemia intermedia

A

hydroxyurea- increase in fetal hemoglobin production.

watch iron absorption- can be increased

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25
Q

outcomes of thalassemia major/erythropoiesis

A

expansion of marrow cavities, extramedullary hematopoiesis, splenic destruction of RBC, hypersplenism, growth failure

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26
Q

treatments for thalassemia major

A

hypertransfusion every 2-4 weeks
splenectomy (in non-transfusion dependent)
stem cell transplant to cure
treat iron overload with chelation

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27
Q

iron overload cause

A

RBC trasfusions
no body mechanism to get rid of excess iron
intake of 1 gm/month in chronic transfusion patients

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28
Q

iron overload complications

A

pericarditis, arrhythmias, cardia failure
fibrosis, cirrhosis, hepatic failure, cancer
diabeter, growth failure, infertility

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29
Q

how to test for iron overload

A

serum ferritin, liver biopsy, MRI

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30
Q

treatment of iron overload

A

chelation (deferasirox or deferoxamine)- start treatment early to prevent iron overload rather than trying to reduce amount of iron in the body if possible.
phlebotomy- regularly remove blood to reduce amount of iron in the blood

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31
Q

sickle cell disease definition

A

group of blood disorders containing HbS

32
Q

is sickle cell dominant or recessive?

A

autosomal recessive

33
Q

sickle cell pathophysiology

A

single point mutation on the beta chain
Adenine to Thymine at position 6 of the beta globin.
changes RBC shape (stiff due to deoxygenation)
blood flow obstruction leads to ischemia

34
Q

epidemiology of sickle cell

A

in US- 8%
1/400 births
3,000,000 with trait and 100,000 with disease

globally more than 400,000 births per year

35
Q

how does sickle cell trait protect against malaria

A

lower transmission
reduced parasitemia
decreased mortality

36
Q

how is sickle cell diagnosed in the US?

A

all newborns tested with dried blood spots

most common disease found by newborn screening

37
Q

newborn screening results

FA

A

normal

38
Q

newborn screening results

FAS

A

sickle cell trait

39
Q

newborn screening results

FS

A

sickle cell anemia

40
Q

newborn screening results

FSA

A

sickle B+ thalassemia

41
Q

newborn screening results

F

A

thalassemia major

42
Q

newborn screening results

FA

A

fast band- alpha thalassemia trait

43
Q

risks for sickle cell trait

A

hematuria
renal medullary carcinoma
sudden death during prolonged, strenuous physical activity

44
Q

hyphema

A

increased occular pressure, loss of vision

those with sickle cell need referral to a specialist to prevent loss of vision

45
Q

clinical manifestations of sickle cell disease

A

functional asplenia, pneumococcal infection
hemolysis (partially compensated- increased reticulocytes)
acute vaso-occlusive events (painful)
organ damage

46
Q

most common cause of death for sickle cell disease patients

A

organ damage- spleen, kidneys, lung, brain, eyes, hips

47
Q

how to prevent sepsis in newborns with sickle cell disease

A

prophylactic therapy with oral penicillin by 3 months

48
Q

penicillin regimen for sepsis prophylaxis with sickle cell

A

125mg BID- until age 3
250mg BID- until age 5
usually has to be refridgerated and picked up every 2 weeks from the pharmacy- difficult to get patients to be compliant

49
Q

why stop prophylaxis at age 5

A

immunizations with HiB, prevnar, pneumovax, meningovax, no evidence of sepsis prevention beyond age 5

50
Q

what temperature is considered a medical emergency for patients with sickle cell disease?

A

38.5 or greater

51
Q

what to order in a SCD patient with fever

A

labs- blood cultures, cbc with retic, UA
chest x-ray
type and cross-match if increased pallor or splenomegaly or resp/neuro symptoms

52
Q

treatment of sepsis in SCD patients

A

IV broad spectrum antibiotics

53
Q

most common manifestation of SCD

A

acute vaso-occlusive pain- occurs as early as 6 months

54
Q

painful events with SCD

A

sudden onset in extremities, back , and sternum/ribs

dactylitis/ hand-foot syndrome

55
Q

treatment of painful events

A

NSAIDs and opioids
fluids and hydration
early pain control

56
Q

warning signs with SCD pain

A 
respiratory distress, chest pain- acute chest syndrome
fever- infection
weakness- stroke
lethargy- splenic sequestration
abdominal pain/jaundice- cholelithiasis
57
Q

symptoms of acute splenic sequestation

A

tender splenomegaly, worsened anemia, increased retics, platelets less than 150,000, LUQ pain, SOB, vomiting

58
Q

typical age of onset of acute splenic sequestation

A

6 months to 3 years

59
Q

treatment of splenic sequestration

A

RBC transfusions

careful not to overshoot

60
Q

recurrence rate of splenic sequestration

A

50%

61
Q

acute chest syndrome signs/symptoms

A

+/-fever, dyspnea, pain, hypoxia, increased WBC, pleural effusion, fat embolism, atelectasis, sickling and intra-pulmonary sequestration

62
Q

acute chest syndrome treatment

A 
admission
antimicrobial treatment- ceftriaxone, azithromycin, levofloxacin
O2
bronchodilators
IV fluids
transfusions
63
Q

avascular necrosis (AVN)

A

osteonecrosis in limited circulation areas

femoral head most common

64
Q

AVN treatment

A

NSAIDs, PT, hip replacement

65
Q

SCD and renal manifestations

A

hyposthenuria
renal infarction
progression to renal failure and proteinuria

66
Q

priapism

A

prolonged, painful erection
40% of men with SCD
blood flow is obstructed

67
Q

priapism treatment

A

analgesics and hydration
aspiration if greater than 4 hours
vasodilators can prevent attacks, but do not treat

68
Q

sickle retinopathy

A

vitreal hemorrhage and retinal detachment
causes vision loss
seen in HbSC > HbSS

69
Q

leg ulcers and SCD

A

5-10% of people > age 10 have healing problems

70
Q

incidence of stroke with SCD

A

11% by age 20

24% by age 45

71
Q

stroke symptoms

A 
hemiparesis (weakness as opposed to pain)
visual/language dysfunction
seizures
headaches
altered sensation
altered mental status
72
Q

treatment of stroke with SCD

A

transfusion immediately
CT
IV fluids
MRI (can wait a few days)

73
Q

stroke recurrence with SCD

A

47-93% without treatment
treat with blood transfusions every 3-4 weeks
10-20% still experience recurrence with treatment

74
Q

stroke prevention in SCD

A 
transcranial doppler (TCD) ultrasonography screening
if > 200 cm/sec- abnormal, requires transfusions
75
Q

indications for simple transfusions

A 
splenic sequestration
transient aplastic crisis
anaemia
acute chest syndrome
pre-ops
76
Q

indications for chronic transfusions

A

clinical stroke
abnormal TCD (>200 cm/sec)
multisystem organ failure

Clin Med - Hematology (9 decks)

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