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Pathoma > Heme (missing last RBC lecture) > Flashcards

Heme (missing last RBC lecture) Flashcards

1
Q

define anemia

A

reduction in circulating RBC mass

100)

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2
Q

surrogates for measuring RBC mass

A

Hb
Hct
RBC count

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3
Q

why does microcytic anemia occur?

A

undergo an extra division

decreased Hb –> divide one extra time to maintain its color

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4
Q

4 microcytic anemias

A

iron deficiency
anemia of chronic disease
sideroblastic
thalassemia

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5
Q

iron deficiency

A

most common nutritional deficiency in the world
absorbed in DUODENUM
heme iron more readily absorbed

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6
Q

transferrin

A

transports iron in blood to liver and bone marrow macrophages
generally one out of three is bound

TIBC: how many TF molecules are in the blood

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7
Q

% saturation?

A

how many TF molecules are bound by iron (normally 33%)

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8
Q

gastrectomy

A

decreased acid, decreased iron in the 2+ state, more in 3+ (acid keeps Fe2+ in that form)

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9
Q

stages of iron deficiency

A

1) storage iron (ferritin) depleted
2) serum iron depleted (and % sat)
3) normocytic anemia (marrow prefers to make fewer RBCs that are still nice)
4) microcytic, hypochromic (larger central pallor due to less Hb) anemia

*TIBC opposes ferritin levels (liver will produce more TIBC to go and find more iron when ferritin goes down)

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10
Q

features of iron deficiency

A

anemia
koilonychia (spoon nails)
pica (chew dirt)

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11
Q

lab findings in iron deficiency

A
  • microcytic, hypochromic anemia
  • increased RDW (spectrum of size) –> greater spectrum (some small some normal, thus incr RDW)
  • low ferritin, high TIBC
  • low serum iron, low % sat
  • high FEP (free protoporphyrin bc not enough iron to bind it)
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12
Q

tx iron deficiency anemia

A 
ferrous sulfate (supp Fe)
need to rule out colonic carcinoma
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13
Q

plummer-vinson syndrome

A

iron-def anemia plus esophageal web & atrophic glossitis

anemia+dysphagia+beefy-red tongue

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14
Q

anemia of chronic disease

acute phase reactants?

A

most common type in hosp pts
incr acute phase reactants: hepcidin (limits iron transfer from MP’s to erythroid precursors)
suppress EPO

*decreased availabilty of iron –> decr Hb –> decr RBC

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15
Q

lab findings in ACD

A 
ferritin up
TIBC down
down serum iron (used by marrow)
down % sat
up FEP

early phase: normocytic anemia
later: microcytic anemia
so can do both

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16
Q

tx of ACD

A

underlying cause of inflammation –> decr hepcidin

EPO –> especially useful in cancer pts

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17
Q

sideroblastic anemia

A

defect in protoporphyrin synthesis –> microcytic anemia

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18
Q

making protoporphyrin

where’s the iron located?

A

SCoA–>ALA (ALAS: rate limiting: B6 cofactor)

ALA–>protoporph (ALAD)

protop+Fe–>heme (ferrokelatase: in mito)

iron transferred to erythroblast, enters mito to create heme; if not making protopo, iron trapped in the mitochondria –> ring of Fe around nucleus –> RINGED SIDEROBLAST

**IN THE MITO

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19
Q

congenital sideroblastic anemia?

3 causes of aquired?

A

defect in ALAS (succCoA–>mva)

alcoholism (destroys protopo)
lead poisoning (destroys ALAD and ferrokelotase)
B6 deficiency (no cofactor for ALAS rxn) think ISONIAZID tx --> B6 def
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20
Q

lab findings in sideroblastic anemia

A

high ferritin, low TIBC
up serum iron, up % sat

when cells die (Fe creates free radicals), iron leaks out and marrow MP’s eat iron and store it

HH has very similar lab findings

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21
Q

thalassemia

A

decreased production/synthesis of globin chains–>down Hb–>microcytic anemia

protection against plasmodium FALCIPARUM malaria

alpha or beta depending on which chains cannot be produced

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22
Q

a-thalassemia

A

GENE DELETION
4 alpha alleles (copies) on Chr 16

1 gene deleted: asymptomatic
2 genes deleted: mild anemia w/slightly up RBC count (same chromosome or opposite? cis v. trans) CIS is worse –> incr risk in offspring, b/c can pass both copies along) higher rate of CIS deletion seen in asians, TRANS common in Africa
3 genes: severe anemia, B chains form tetramers that damage RBC’s (HbH seen on electrophoresis)
4 genes: in fetus, gamma tetramer causes fetal death in utero (HYDROPS FETALIS) **Tetramer of gamma=Hb BARTS

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23
Q

tetramer of Hb Beta?

A

HbH

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24
Q

B-thalassemia

A

due to MUTATIONS (not deletions)
B null and B+

B/B+ (minor, slight decr in production of B globin): mildest, asymptomatic w/up RBC count; microcytic hypochromic RBC’s w TARGET CELLS

increase in HbA2 to 5%
increase HbF to 2%

25
Q

target cell

A

bleb in membrane

26
Q

B-thalassemia major

A

B null/B null
no problem in fetus
when born, severe anemia in months; HbF is protective
alpha tetramers–>ineffective erythropoiesis
extravascular hemolysis (in spleen)

massive erythroid hyperplasia (extra medullary hematopoiesis with HSM)
risk of aplastic crisis with parvovirus B19 (infects and shuts down erythroid precursors)

“chipmunk-like face”
“crew-cut appearance” on X-ray

27
Q

tx of thalassemia?
smear?
electrophoresis?

A

chronic transfusions
–> risk of 2ndary hemochromatosis

microcytic, hypochromic, target cells and nucleated RBC’s (due to being made in abnormal location)

no HbA, only HbA2 and HbF

28
Q

macrocytic anemia (MCV >100)

A

B12/folate deficiency (megaloblastic)

why would one less division occur? due to loss of DNA precursors

29
Q

folate jazz

A

comes into body as THF–>methylated–>needs to then lose the methyl group to become DNA precursor (so gives it to B12) then B12 gives it to homocysteine, which becomes methionine

megaloblastic: b/c other cells that are dividing are also affected

30
Q

changes in lack of folate or B12?

A 
megaloblastic anemia
hypersegmented NPs (>5 lobes)
change in rapidly-dividing cells e.g. intestine
31
Q

other causes of macrocytic anemia

A

alcoholism; liver disease; drugs (5-FU)

32
Q

2 major causes of megaloblastic anemia

A

folate deficiency: abs in jejunum, develops in months (limited stores; alcoholics/elderly/incr demand/folate antagonists e.g. MTXate)

B12 deficiency: binds R binding; cleaved via proteases in SI, then binds IF and goes to ileum to be absorbed (less common than folate def) takes years to develop due to large hepatic stores

33
Q

lab findings of folate deficiency?

A 
macrocytic RBC and hypersegmented NP's
glossitis
down serum folate
up serum homocysteine
normal methylmalonic acid (B12 needed to convert to succCoA; but this isn't the problem)
34
Q

pernicious anemia

A

AI destruction of parietal cells (no IF) then cannot bind B12 to absorb in ileum

35
Q

parietal cells

A

Pink
Proton pumps (make acid)
Pernicious anemia

36
Q

other causes of VitB12 deficiency?

A

pancreatic insuff: cannot cleave B12 from R-binder (produced by saliva glands in mouth)

terminal ileum damage (Crohn, diphyllobothrium datum fish tapeworm, vegans may have dietary deficiency)

37
Q

lab changes in B12 deficiency

A 
macrocytic anemia w/hypersegmented NP's
glossitis
low serum B12
up serum homocysteine
up methylmalonic acid
subacute combined degeneration of spinal cord (buildup of methymalonic acid in myelin of spinal cord**this would not be seen in FOLATE DEF)
38
Q

2 B12 rxns in body

A

making DNA precursors

making SuccCoA from methylmalonic acid (this can buildup and damage the spinal cord)

39
Q

normocytic anemia

Q: peripheral destruction? or underproduction?

A

check retic #
normal marrow will bump retics to >3%
BUT the retic count is falsely elevated bc you just have fewer RBCs (must correct by Hct/45–>fraction of normal Hct)

40
Q

extravascular

A

RE system: macrophages of liver, spleen, lymph nodes

41
Q

macrophage digestion

A

globin –> AA’s
heme –> iron and protopo
protopo –> unconjugated bilirubin (–>serum to bind albumin and sent to liver for conjugation and excretion into bile)

42
Q

clinical findings w/extravascular hemolysis

A

anemia w/splenomegaly
jaundice due to unconj bilirubin (liver can’t keep up)
incr risk for bilirubin gallstones
marrow hyperplasia w/corrected retic count >3%

43
Q

intravascular hemolysis

A

haptoglobin binds Hb to save it from excretion (so earliest change is haptoglobin decrease)
later will see Hb in the urine

44
Q

lab findings of intravasc hemolysis

A

hemoglobinemia
hemoglobinuria
hemosiderinuria (Hb taken up and broken down and iron stored in renal tubular cells and sloughed)
decr serum haptoglobin

45
Q

hereditary spherocytosis

A

inherited defect of RBC cytoskeleton-membrane tethering proteins (spectrin, ankryn, band 3.1)

blebs are formed over time –> loss of biconcave shape and central pallor too (oldest cells will have lost the most membrane and thus smallest)

less able to maneuver thru spleen; consumed –> anemia

46
Q

lab findings of spherocytosis

A

spherocytes w/loss of central pallor
up RDW and MCHC (bc Hb is concentrated)
splenomegaly “work hypertrophy”, jaundice w/unconj bilirubin, and gallstones
risk for APLASTIC CRISIS w/parvovirus B19 of erythroid precursors

47
Q

dx spherocytosis?

tx?

A

osmotic fragility test: increased fragility in hypotonic solution (cells burst more easily than normal cells)

splenectomy: anemia resolves, spherocytes persist, HOWELL-JOLLY bodies emerge on smear (it is the job of the spleen to remove residual DNA fragments)

48
Q

sickle cell anemia

A

recessive MUT in B Hb chain
glut (phillic) replaced w/valine (phobic)
protective v malaria

disease when 2 abnormal B genes –> >90% HbS in RBC’s –> polymerizes when deoxygenated

49
Q

increased risk of sickling

A

hypoxemia
dehydration
acidosis

every time RBC’s pass through capillaries they sickle (deoxygenate) and cause damage to cell membrane (some cells will lyse, some will be digested…both intra/extravascular hemolysis)

HbF is protective for first months

50
Q

tx of sickle cell?

A

hydroxyurea increases levels of HbF

51
Q

findings in sickle cell

A

target cells (dehydration –> leaking cytoplasm–> extra membrane –> blebs)
massive erythroid hyperplasia (expansion of hematopoeisis)
extramedullary hematopoesis w/hepatomegaly
risk of aplastic crisis w/PB19

52
Q

irreversible sickling

A

vaso-occlusion:
dactylitis (presenting sign)
autosplenectomy (infarction due to loss of blood supply) and loss and incr risk of capsulated bugs
also incr risk of S. paratyphoid
HJ bodies on smear (no more spleen)
acute chest syndrome (occl pull microcirculation)

53
Q

acute chest syndrome (vasoocclusive crisis)

A 
vaso-occlusion in pulm microcirculation
present w/chest pain, SOB, lung infiltrates
precipitated by pneumonia
most common COD in adults
COD in kids is infection w/encaps orgs
54
Q

renal papillary necrosis

A

gross hematuria and proteinuria

55
Q

sickle cell trait

A

one mutated gene
produce both HbA and HbS
going to have <50% of HbS bc production of HbA is more efficient, therefore will be asymptomatic, except for RENAL MEDULLA

56
Q

renal medulla

A

extreme hypoxia/hypertonicity (cause sickling)
microinfarctions
microscopic hematuria
eventual decreased ability to conc urine

57
Q

lab findings in sickle cell anemia

electrophoresis shows? (HbS/F/A2/A)

A

sickle cells/targets in sickle cell disease, but NOT “TRAIT”

Metabisulfite screen: causes cells w/ ANY HbS to sickle (+ in both disease and trait)

Disease: 90% HbS, 8% HbF, 2% HbA2, NO HbA
Trait: 55% HbA, 43% HbS, 2% HbA2

58
Q

HbC (has lyCeene)

A

AR MUT in B chain of Hb
normal glut acid replaced by lysine
less common than sickle cell disease

see HbC crystals on smear

Pathoma (5 decks)

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