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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
target cell
bleb in membrane
26
B-thalassemia major
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
tx of thalassemia? smear? electrophoresis?
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
macrocytic anemia (MCV >100)
B12/folate deficiency (megaloblastic) | why would one less division occur? due to loss of DNA precursors
29
folate jazz
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
changes in lack of folate or B12?
``` megaloblastic anemia hypersegmented NPs (>5 lobes) change in rapidly-dividing cells e.g. intestine ```
31
other causes of macrocytic anemia
alcoholism; liver disease; drugs (5-FU)
32
2 major causes of megaloblastic anemia
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
lab findings of folate deficiency?
``` 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
pernicious anemia
AI destruction of parietal cells (no IF) then cannot bind B12 to absorb in ileum
35
parietal cells
Pink Proton pumps (make acid) Pernicious anemia
36
other causes of VitB12 deficiency?
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
lab changes in B12 deficiency
``` 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
2 B12 rxns in body
making DNA precursors | making SuccCoA from methylmalonic acid (this can buildup and damage the spinal cord)
39
normocytic anemia | Q: peripheral destruction? or underproduction?
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
extravascular
RE system: macrophages of liver, spleen, lymph nodes
41
macrophage digestion
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
clinical findings w/extravascular hemolysis
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
intravascular hemolysis
haptoglobin binds Hb to save it from excretion (so earliest change is haptoglobin decrease) later will see Hb in the urine
44
lab findings of intravasc hemolysis
hemoglobinemia hemoglobinuria hemosiderinuria (Hb taken up and broken down and iron stored in renal tubular cells and sloughed) decr serum haptoglobin
45
hereditary spherocytosis
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
lab findings of spherocytosis
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
dx spherocytosis? | tx?
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
sickle cell anemia
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
increased risk of sickling
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
tx of sickle cell?
hydroxyurea increases levels of HbF
51
findings in sickle cell
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
irreversible sickling
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
acute chest syndrome (vasoocclusive crisis)
``` 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
renal papillary necrosis
gross hematuria and proteinuria
55
sickle cell trait
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
renal medulla
extreme hypoxia/hypertonicity (cause sickling) microinfarctions microscopic hematuria eventual decreased ability to conc urine
57
lab findings in sickle cell anemia | electrophoresis shows? (HbS/F/A2/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
HbC (has lyCeene)
AR MUT in B chain of Hb normal glut acid replaced by lysine less common than sickle cell disease see HbC crystals on smear

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