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Clin Med - Hematology > Hemoglobinopathies > Flashcards

Hemoglobinopathies Flashcards

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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
outcomes of thalassemia major/erythropoiesis
expansion of marrow cavities, extramedullary hematopoiesis, splenic destruction of RBC, hypersplenism, growth failure
26
treatments for thalassemia major
hypertransfusion every 2-4 weeks splenectomy (in non-transfusion dependent) stem cell transplant to cure treat iron overload with chelation
27
iron overload cause
RBC trasfusions no body mechanism to get rid of excess iron intake of 1 gm/month in chronic transfusion patients
28
iron overload complications
pericarditis, arrhythmias, cardia failure fibrosis, cirrhosis, hepatic failure, cancer diabeter, growth failure, infertility
29
how to test for iron overload
serum ferritin, liver biopsy, MRI
30
treatment of iron overload
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
31
sickle cell disease definition
group of blood disorders containing HbS
32
is sickle cell dominant or recessive?
autosomal recessive
33
sickle cell pathophysiology
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
epidemiology of sickle cell
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
how does sickle cell trait protect against malaria
lower transmission reduced parasitemia decreased mortality
36
how is sickle cell diagnosed in the US?
all newborns tested with dried blood spots | most common disease found by newborn screening
37
newborn screening results | FA
normal
38
newborn screening results | FAS
sickle cell trait
39
newborn screening results | FS
sickle cell anemia
40
newborn screening results | FSA
sickle B+ thalassemia
41
newborn screening results | F
thalassemia major
42
newborn screening results | FA
fast band- alpha thalassemia trait
43
risks for sickle cell trait
hematuria renal medullary carcinoma sudden death during prolonged, strenuous physical activity
44
hyphema
increased occular pressure, loss of vision | those with sickle cell need referral to a specialist to prevent loss of vision
45
clinical manifestations of sickle cell disease
functional asplenia, pneumococcal infection hemolysis (partially compensated- increased reticulocytes) acute vaso-occlusive events (painful) organ damage
46
most common cause of death for sickle cell disease patients
organ damage- spleen, kidneys, lung, brain, eyes, hips
47
how to prevent sepsis in newborns with sickle cell disease
prophylactic therapy with oral penicillin by 3 months
48
penicillin regimen for sepsis prophylaxis with sickle cell
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
why stop prophylaxis at age 5
immunizations with HiB, prevnar, pneumovax, meningovax, no evidence of sepsis prevention beyond age 5
50
what temperature is considered a medical emergency for patients with sickle cell disease?
38.5 or greater
51
what to order in a SCD patient with fever
labs- blood cultures, cbc with retic, UA chest x-ray type and cross-match if increased pallor or splenomegaly or resp/neuro symptoms
52
treatment of sepsis in SCD patients
IV broad spectrum antibiotics
53
most common manifestation of SCD
acute vaso-occlusive pain- occurs as early as 6 months
54
painful events with SCD
sudden onset in extremities, back , and sternum/ribs | dactylitis/ hand-foot syndrome
55
treatment of painful events
NSAIDs and opioids fluids and hydration early pain control
56
warning signs with SCD pain
``` respiratory distress, chest pain- acute chest syndrome fever- infection weakness- stroke lethargy- splenic sequestration abdominal pain/jaundice- cholelithiasis ```
57
symptoms of acute splenic sequestation
tender splenomegaly, worsened anemia, increased retics, platelets less than 150,000, LUQ pain, SOB, vomiting
58
typical age of onset of acute splenic sequestation
6 months to 3 years
59
treatment of splenic sequestration
RBC transfusions | careful not to overshoot
60
recurrence rate of splenic sequestration
50%
61
acute chest syndrome signs/symptoms
+/-fever, dyspnea, pain, hypoxia, increased WBC, pleural effusion, fat embolism, atelectasis, sickling and intra-pulmonary sequestration
62
acute chest syndrome treatment
``` admission antimicrobial treatment- ceftriaxone, azithromycin, levofloxacin O2 bronchodilators IV fluids transfusions ```
63
avascular necrosis (AVN)
osteonecrosis in limited circulation areas | femoral head most common
64
AVN treatment
NSAIDs, PT, hip replacement
65
SCD and renal manifestations
hyposthenuria renal infarction progression to renal failure and proteinuria
66
priapism
prolonged, painful erection 40% of men with SCD blood flow is obstructed
67
priapism treatment
analgesics and hydration aspiration if greater than 4 hours vasodilators can prevent attacks, but do not treat
68
sickle retinopathy
vitreal hemorrhage and retinal detachment causes vision loss seen in HbSC > HbSS
69
leg ulcers and SCD
5-10% of people > age 10 have healing problems
70
incidence of stroke with SCD
11% by age 20 | 24% by age 45
71
stroke symptoms
``` hemiparesis (weakness as opposed to pain) visual/language dysfunction seizures headaches altered sensation altered mental status ```
72
treatment of stroke with SCD
transfusion immediately CT IV fluids MRI (can wait a few days)
73
stroke recurrence with SCD
47-93% without treatment treat with blood transfusions every 3-4 weeks 10-20% still experience recurrence with treatment
74
stroke prevention in SCD
``` transcranial doppler (TCD) ultrasonography screening if > 200 cm/sec- abnormal, requires transfusions ```
75
indications for simple transfusions
``` splenic sequestration transient aplastic crisis anaemia acute chest syndrome pre-ops ```
76
indications for chronic transfusions
clinical stroke abnormal TCD (>200 cm/sec) multisystem organ failure

Clin Med - Hematology (9 decks)

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