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Mercy CLS 6: Hematology > 7) Anemias of disordered iron metabolism & heme synthesis > Flashcards

7) Anemias of disordered iron metabolism & heme synthesis Flashcards

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1
Q

distribution of Fe in the body
- 70%…
- 25%…
- 4%…
- 1%…

A
  • 70% in hemoglobin
  • 25% as storage/serum iron
  • 4% in myoglobin
  • 1% in iron-containing enzymes
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2
Q

average adult total body iron

A

2.5-4 g
2/3 bound to heme

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3
Q

iron absorbed per day

A

about 1.5 mg
5% of daily need

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4
Q

iron needed to make 1 mL of RBCs
iron needed per day for new Hgb

A

0.5 mg
20 mg

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5
Q

3 processes that maintain iron homeostasis

A
  • dietary iron
  • recycling of iron from destroyed RBCs
  • iron storage
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6
Q

5 phases of iron metabolism

A
  • absorption
  • transport
  • storage
  • loss
  • utilization
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7
Q

cause increased Fe absorption

A
  • decreased Fe stores
  • erythropoiesis
  • large amounts of Fe ingestion
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8
Q

special factors known to affect Fe absorption

A
  • ascorbic acid and citric acid ↑ absorption
  • gastric juices ↑ absorption
  • phosphates, phytates, tannates ↓ absorption
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9
Q

2 forms of dietary Fe

A
  • heme Fe —red meats and fish, ferrous form
  • nonheme Fe —veggies and whole grains, ferric form
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10
Q

function of ferric reductase

A

reduces dietary ferric iron to ferrous iron, so it can be absorbed by intestinal mucosal cells

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11
Q

function of ferrooxidase

A

oxidizes ferrous iron in intestinal mucosal cell back to ferric iron, so it can bind to transferrin and be transported

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12
Q

transferrin binds ——– iron

A

ferric, 3+

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13
Q

serum iron measures…

A

transferrin-bound iron

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14
Q

iron measure affected by diurnal variation

A

serum iron
30% higher in morning

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15
Q

total iron binding capacity measures…

A

amount of iron bound if transferrin was fully saturated

normally, it is 1/3 saturated

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16
Q

TIBC equation

A

TIBC = UIBC + serum Fe

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17
Q

functional TIBC test

A
  • excess Fe added to serum
  • unbound Fe removed
  • iron content of serum remeasured
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18
Q

% Fe saturation measures…

A

relates amount of iron present in the serum to amount of transferrin present (TIBC)

% sat = 100(serum Fe)/TIBC

normal = 33%

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19
Q

places ferritin can be stored

A
  • mucosal cells
  • BM
  • spleen
  • liver
  • plasma
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20
Q

3 places transferrin can take Fe

A
  • normoblasts (BM)
  • liver, spleen
  • other body cells
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21
Q

2 storage forms of iron

A

ferritin
hemosiderin

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22
Q

ferritin composition

A

ferric hydroxyphosphate
apoferritin

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23
Q

cannot be seen with usual iron stain

A

ferritin

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24
Q

amount of circulating ——– parallels concentration of storage Fe

A

ferritin

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25
seen in unstained tissues as golden-brown granules seen in Prussian blue stained tissues
hemosiderin
26
longer-term, larger capacity storage of Fe
hemosiderin
27
Fe deposits in the tissues, accumulates in macrophages in the RES
hemosiderosis
28
2 ways to accelerate Fe excretion
- chelating agents - therapeutic phlebotomy
29
2 methods of transferring iron to developing RBCs
- transferrin-bound iron delivered to receptor sites - **Ropheocytosis**: normoblasts encircle macrophages with iron (nursing red cells)
30
3 causes of IDA
- increased demand (birth through infancy, pregnancy) - decreased absorption - increased loss (donation, pregnancy, menstruation, GI bleeds)
31
3 stages of IDA
1. Fe depletion 2. Fe deficient erythropoiesis 3. Fe deficiency anemia
32
events in stage 1 of IDA
- decrease in serum ferritin and hemosiderin - increased mucosal absorption - no anemic sx
33
events in stage 2 IDA
- TIBC increased - % sat decreased to 15% - serum iron decreased - FEP increased - normocytic, normochromic RBCs
34
events in stage 3 IDA
- Hgb, Hct, MCV decreased - hypochromic microcytes appear - RDW increased - anemix sx (fatigue, dizziness, paresthesia, chelitis, pica)
35
chelitis
chapped lips IDA sx
36
IDA may cause ------ platelet ct because...
↑ increased CFU-EMk more megakaryocytes
37
sideropenic state
low iron no/few sideroblasts
38
if ----------- is found in BM, IDA is excluded if ------------ are absent or decreased, it is suspected
hemosiderin sideroblasts
39
first indicator of IDA
decreased serum ferritin
40
serum ferritin no longer correlates with stored iron if it is decreased below...
12 μg/L
41
not a good indicator of IDA, affected by many other things
transferrin levels
42
protoporphyrins found in IDA
FEP zinc protoporphyrins
43
tx for dietary IDA
oral ferrous sulfate
44
it takes ----- to correct 1/2 cases of IDA
3 weeks
45
autosomal recessive disorder affecting 1/200 Americans most common form of Fe overload
hereditary hematochromatosis
46
in patients with HH, ------ of Fe are absorbed daily
4 mg
47
HH generally manifests in...
males 50s-60s
48
Bronze diabetes
HH
49
body has adequate iron, but is unable to incorporate it into hemoglobin
sideroblastic anemia
50
classic sign of sideroblastic anemia
ringed sideroblasts Fe accumulates in mitochondria of young RBCs, forms ring around nucleus
51
3 categories of sideroblastic anemia
- hereditary - acquired - idiopathic
52
hereditary SA population
young males first 30 years of life
53
2 common causes of acquired SA
- lead poisoning - alcohol abuse
54
coarse basophilic stippling high FEP
lead poisoning
55
tx for lead poisoning
lead chelating agents
56
idiopathic SA is considered a... (2)
myelodysplastic syndrome (MDS) refractory anemia with ringed sideroblasts (RARS)
57
idiopathic SA often ends in...
leukemia
58
micro/hypo anemia with ↓ retics
sideroblastic anemia | RS lyse before release into PB
59
increased RDW pappenheimer bodies high % sat transferrin
sideroblastic anemia
60
iron-laden non-nucleated RBCs
siderocytes
61
definitive direct test for assessing iron deposition and tissue damage in iron overload states
liver biopsy

Mercy CLS 6: Hematology (25 decks)

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