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HemOnc Week 1 > ICL 3.1: Disorders of Hemoglobin > Flashcards

ICL 3.1: Disorders of Hemoglobin Flashcards

1
Q

why do you want iron on the inside the porphyrin ring of heme?

A

oxygen doesn’t dissolve in water and we are mostly water

so oxygen has to be held to the iron on the inside so it can be carried around the body

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2
Q

how many Hb molecules are there in one RBC?

A

280 million

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3
Q

in what population is it not okay to have low Fe?

A

kids

you need the iron for growth

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4
Q

what chromosome are the alpha globin chain genes on?

A

16

4 alleles, 2 on each chromosome 16

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5
Q

what type of Hb do you have when you’re an embryo vs fetus vs adult

A

embryo: ζ2ε2
fetus: α2γ2
adult: α2β2

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6
Q

what chromosome are the ζ globin genes on?

A

chromsome 16

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7
Q

what chromosome are the β globin genes on?

A

chromsome 11

1 allele each

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8
Q

what chromosome are the γ globin genes on?

A

chromosome 11

2 alleles each

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9
Q

what chromosome is the ε globin chain on?

A

chromosome 11

1 allele each

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10
Q

what is the structure of hemoglobin?

A

4 globin chain

each globin chain holds on to one porphyrin ring and each porphyrin ring holds onto one iron molecule

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11
Q

how many AA make up each α globin chain?

A

141 AA

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12
Q

how many AA make up each β globin chain?

A

146 AA

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13
Q

how many total AA does HbA1 have?

A

574 AA

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14
Q

what holds together the four subunits of hemoglobin?

A

non-covalent interactions

ex. hydrophobic, ionic and hydrogen bonds

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15
Q

what types of hemoglobin are in an adult?

A

HbA1 (95%)

HbA2 (<3%)

HbF (1-2%)

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16
Q

how is oxygen released?

A

CO2 has more affinity to Hb than oxygen

so when oxygen gets to the tissues, CO2 displaces oxygen and it’s released

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17
Q

if you give a patient with a Hb=3.5 a blood transfusion, what will happen?

A

they will die from circulatory overload

in chronic anemia, their body overtime has adjusted and is used to a Hb this low

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18
Q

what’s a normal WBC count?

A

4000-10,000 /μL

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19
Q

what’s a normal RBC count?

A

male: 4.6-6 x 10ˆ6/μL
female: 4.2-5.4x10ˆ6/μL

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20
Q

what’s a normal Hb level?

A

male: 14-18 g/dL
female: 12-16 g/dL

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21
Q

what’s a normal Hct level?

A

male: 42-50%
female: 37-47%

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22
Q

what’s a normal MCV?

A

75-100 fL

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23
Q

what’s a hemoglobinopathy?

A

genetic defect that results in abnormal structure of one of the globin chains of the Hb molecules

inherited single-gene disorders

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24
Q

what is hereditary persistence of fetal hemoglobin?

A

HPFH

failure to silence genes

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25
Q

what’s a quantitative defect type of Hb abnormality?

A

thalassemia

imbalance of chain synthesis

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26
Q

what is a qualitative defect type of Hb abnormality?

A

sickle cell

additional, substitutions or deletions of AA

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27
Q

what is the HbC mutation?

A

Glu6Lys point mutation

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28
Q

what is the HbD mutation?

A

Glu121Gln point mutation

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29
Q

what is the HbE mutation?

A

Glu26Lys point mutation

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30
Q

what are Howell-Jolly bodies?

A

denatured DNA

seen in sickle cell disease

this tells you that the person has no spleen! the spleen should be removing anything that is abnormal and Howell-Jolly bodies aren’t normal

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31
Q

what is seen in the blood smear of alpha thalassemia?

A

Heinz bodies

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32
Q

how do you diagnose an alpha thalassemia silent carrier?

A

must do genetic testing!

their Hb electrophoresis will look normal

Hb electrophoresis works for everything else

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33
Q

what globin chains get up or down-regulated in alpha thalassemia?

A

nothing gets down or upregulated

the only other Hb gene on chromosome 16 is ζ but it’s gone so NOTHING gets upregulated in alpha thalassemia

34
Q

what is seen on x-rays of Hb disorders?

A

bone marrow expansion leads to hair-on-end X ray

seen in sickle cell and thalassemia and other Hb disorders

you will never see this in iron deficiencies

35
Q

what is commonly seen on the blood smear of a thalassemia?

A

target cells

36
Q

what populations have thalassemia?

A

african

mediterranean

37
Q

how are iron levels effected in thalassemia?

A

they’re either normal or high

chronic hemolysis is happening which leads to iron overload states

38
Q

what is the sickle cell mutation?

A

glu6val in the B chain

  • to neutral charge

hydrophobic val stick together and sickle

MCV normal

39
Q

what’s the benefit to having sickle cell trait?

A

sick cell trail = 1 normal B chain and 1 sickle B chain

protects against malaria

40
Q

what problems does sickle cell disease cause?

A

microvascular occlusion

sticky RBCs

decreased NO by free Hb

41
Q

what is SC disease?

A

Hemoglobin Sickle cell Disease

one HbS B chain and one HbC b chain

milder disease

MCV normal

42
Q

what is S-thalassemia?

A

1 sickle B chain and 1 B chain thalassemia type

mildest disease because increased HbF helps compensate

sickled and target cells

decreased MCV = microcytic

43
Q

what are the 5 types of sickle cell crisis?

A
  1. sequestration crisis
  2. aplastic crisis*
  3. hemolytic crisis*
  4. megaloblastic crisis
  5. vaso-occlusive crisis*
44
Q

what is sequestration crisis?

A

kids only

acute splenomegaly

hypotension

possible death

45
Q

what do sickle cell patients need a supplement of?

A

folate

to keep up with RBC production that’s needed due to all the hemolysis

46
Q

what is dactylitis?

A

seen in kids only

really puffy red swollen hands

47
Q

what is acute chest syndrome?

A

lots of sickling in the lungs

you have to do a transfusion to replace sickled RBCs with normal RBCs

48
Q

what things have improved sickle cell patient life spans?

A
  1. penicillin antibiotics
  2. transfusions
  3. hydroxyurea
49
Q

what is HbC disease?

A

glu6lys substitution

because + lysin, HbC moves more slowly on electrophoresis compared to HbA and HbS

mild hemolytic anemia

no specific therapy is recommended because it’s usually not that bad!

50
Q

what is porphyria?

A

heme synthesis enzyme deficiency

if you’re missing an enzyme in the heme synthesis pathway, it all back-up and the rest of the enzymes build up

you can’t make heme so you need oxygen and you can’t go out into the sun because the porphyrin precursors have a lot of photosensitivity = this is where the myths of vampires comes from!

51
Q

how is HepC related to porphyria?

A

HepC can cause porphyria!!

so treat HepC and you can fix the porphyria

52
Q

what is the classical symptom combination associated with porphyria?

A

abdominal symptoms

AND

neuropsychiatric symptoms

53
Q

what symptoms are associated with porphyria?

A
  1. abdominal
  2. neuropsychiatric
  3. skin rashes
  4. dark urine when exposed to sunlight
54
Q

what are the two ways porphyria can be classified?

A
  1. symptomatically
    - acute
    - cutaneous
  2. pathophysiology
    - hepatic
    - erythropoietic

based on the sites of accumulation of heme precursors, either in the liver or bone marrow and RBC

everything except one porphyria is hepatic

55
Q

what are the types of acute porphyria?

A

ALA-D deficiency porphyria

acute intermittent porphyria

variegate porphyria

hereditary coproporphyria

56
Q

what are the types of non-acute porphyria

A

porphyria cutanea tarda

erythropoietic prootophorphyria

congenital erythropoietic porphyria

57
Q

what is acute intermittent porphyria?

A

type of inherited hepatic porphyria

uroporphyrinogen I synthase deficiency = porphobilinogen deaminase

normally, porphobilinigoen –> hydroxymethylbilane via UPSI but without it, porphobilinogen and ALA build up

increased excretion of porphobilinogen & γ-ALA

urine gets darkened on exposure to air due to conversion of porphobilinogen to porphobilin & porphyrin

58
Q

what enzyme is effected in acute intermittent porphyria?

A

uroporphyrinogen I synthase

59
Q

when is acute intermittent porphyria expressed?

A

after puberty

60
Q

what’s the inheritance of acute intermittent porphyria?

A

autosomal dominant

61
Q

in what population is acute intermittent porphyria most common?

A

affects all races and ethnicities

more common in caucasians

occurs predominantly in woman (80%)

62
Q

what acute porphyria is most common?

A

acute intermittent porphyria

63
Q

what are the aggravating factors for acute porphyrias?

A
  • drugs and chemicals (anti-seizure medications)
  • luteal phase of menstrual cycle
  • pregnancy
  • post-partum period
  • infection
  • stress/exhaustion
  • fasting/starvation
  • surgery

some of these reasons are why women are the ones effected by acute intermittent porphyria 80%

64
Q

what are some porphyria treatment options?

A

liver transplant

stop medications that triggered symptoms

treat infections that may have caused symptoms

IV glucose

IV fluids

hemin injections production of porphyrin

65
Q

how does IV glucose help treat porphyria?

A

IV glucose inhibits porphyrin pathway via negative feedback

66
Q

injections of what helps with porphyria?

A

hemin injections

a form of heme but help limit the body’s production of porphyrin

67
Q

what is methemoglobinemia?

A

increased levels of methemoglobin

methemoglobin is a form of Hb that has ferric Fe+3 which can’t bind oxygen!

normal Hb goes from Fe+2 to Fe+3 when it binds oxygen so methemoglobin is already in Fe+3 state

oxygen binding to methemoglobin increases the affinity for oxygen in the hemes with Fe+2 which decreases the ability of the RBC to release oxygen

can be acquired or born with it

68
Q

where in the US do you find people born with methemoglobinemia?

A

appalachian areas because there’s inbreeding

69
Q

what are the two types of methemoglobinemia?

A
  1. inherited

2. acquired (more common; usually from antibiotics)

70
Q

what are the types of inherited methemoglobinemia?

A
  1. cytochrome b5 reductase deficiency

2. hemoglobin M disease

71
Q

what are the types of cytochrome b5 reductase deficiencies?

A

type I: limited to RBCs

type II: all cells - most die in infancy

72
Q

what are some methemoglobin-inducing agents?

A

lots of common things can cause it!

*naphthalene = moth balls!

nitrofurantoin = common antibiotic for UTI

amyl nitrite

aniline dyes

chlorates

food additives

inks

lidocaine

local anesthetics

nitrates

shoe dye/polish

73
Q

what are the symptoms of methemoglobinemia?

A

based on methemoglobin concentration

0-3%: no symptoms

10-20%: mild symptoms, cyanosis, chocolate brown blood from high methemoglobin levels

20-50%: dyspnea, decreased exercise tolerance, fatigue, HA, dizziness, tachycardia

> 50%: CNS hypoxia, seizures, coma, dysrhythmias, ischemia, tachypnea, metabolic acidosis

> 70%: death

74
Q

what’s a hallmark of methemoglobinemia?

A

brown blood!!!

it’s from the methemoglobinemia that’s brown in color

75
Q

how do you treat methemoglobinemia?

A

methylene blue! it’s an antiseptic dye

methb-reductase turns MetHb (Fe+3) –> Hb (Fe+2)

vitamin C can also reduce Fe+3 to Fe+2

76
Q

how does CO poisoning happen?

A

CO binds super tightly to Hb and displaces oxygen from Hb

this only happens when CO concentration gets high

**cherry red skin

77
Q

what are some sources of CO?

A

tons of common stuff!

gas or wood-burning fireplace

car left running in garage

portable generators

portable kerosene gas heaters

loose vent pipes

improperly installed kitchen range/vent

78
Q

what are the symptoms of carbon monoxide poisoning?

A

depends on the % of CO in blood

<10%: none

20-30%:drowsiness, headache, increased respiratory rate, dizziness, headache, nausea

30-40%: impaired judgement, difficulty breathing, blurry vision, bad headache, more drowsiness, stomach pain

40-50%: confusion, pounding headache, uncontrolled sleep, vertigo, chest pain, memory loss

> 50%: seizure, unconsciousness, heart attack

79
Q

how do you treat CO poisoning?

A

hyperbaric oxygen for about 5 hours to displace CO

it can only go out through the lungs! Just have to breath it out

keep giving till confusion stops

80
Q

what does the oxygen association curve look like for CO poisoning?

A

oxygen tension vs. HbO2% saturation

shifted to the left

CO is staying attached to Hb

HemOnc Week 1 (32 decks)

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