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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

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
Q

seen in unstained tissues as golden-brown granules
seen in Prussian blue stained tissues

A

hemosiderin

26
Q

longer-term, larger capacity storage of Fe

A

hemosiderin

27
Q

Fe deposits in the tissues, accumulates in macrophages in the RES

A

hemosiderosis

28
Q

2 ways to accelerate Fe excretion

A
  • chelating agents
  • therapeutic phlebotomy
29
Q

2 methods of transferring iron to developing RBCs

A
  • transferrin-bound iron delivered to receptor sites
  • Ropheocytosis: normoblasts encircle macrophages with iron (nursing red cells)
30
Q

3 causes of IDA

A
  • increased demand (birth through infancy, pregnancy)
  • decreased absorption
  • increased loss (donation, pregnancy, menstruation, GI bleeds)
31
Q

3 stages of IDA

A
  1. Fe depletion
  2. Fe deficient erythropoiesis
  3. Fe deficiency anemia
32
Q

events in stage 1 of IDA

A
  • decrease in serum ferritin and hemosiderin
  • increased mucosal absorption
  • no anemic sx
33
Q

events in stage 2 IDA

A
  • TIBC increased
  • % sat decreased to 15%
  • serum iron decreased
  • FEP increased
  • normocytic, normochromic RBCs
34
Q

events in stage 3 IDA

A
  • Hgb, Hct, MCV decreased
  • hypochromic microcytes appear
  • RDW increased
  • anemix sx (fatigue, dizziness, paresthesia, chelitis, pica)
35
Q

chelitis

A

chapped lips
IDA sx

36
Q

IDA may cause —— platelet ct because…

A

↑
increased CFU-EMk
more megakaryocytes

37
Q

sideropenic state

A

low iron
no/few sideroblasts

38
Q

if ———– is found in BM, IDA is excluded

if ———— are absent or decreased, it is suspected

A

hemosiderin
sideroblasts

39
Q

first indicator of IDA

A

decreased serum ferritin

40
Q

serum ferritin no longer correlates with stored iron if it is decreased below…

A

12 μg/L

41
Q

not a good indicator of IDA, affected by many other things

A

transferrin levels

42
Q

protoporphyrins found in IDA

A

FEP
zinc protoporphyrins

43
Q

tx for dietary IDA

A

oral ferrous sulfate

44
Q

it takes —– to correct 1/2 cases of IDA

A

3 weeks

45
Q

autosomal recessive disorder affecting 1/200 Americans
most common form of Fe overload

A

hereditary hematochromatosis

46
Q

in patients with HH, —— of Fe are absorbed daily

A

4 mg

47
Q

HH generally manifests in…

A

males 50s-60s

48
Q

Bronze diabetes

A

HH

49
Q

body has adequate iron, but is unable to incorporate it into hemoglobin

A

sideroblastic anemia

50
Q

classic sign of sideroblastic anemia

A

ringed sideroblasts

Fe accumulates in mitochondria of young RBCs, forms ring around nucleus

51
Q

3 categories of sideroblastic anemia

A
  • hereditary
  • acquired
  • idiopathic
52
Q

hereditary SA population

A

young males
first 30 years of life

53
Q

2 common causes of acquired SA

A
  • lead poisoning
  • alcohol abuse
54
Q

coarse basophilic stippling
high FEP

A

lead poisoning

55
Q

tx for lead poisoning

A

lead chelating agents

56
Q

idiopathic SA is considered a… (2)

A

myelodysplastic syndrome (MDS)
refractory anemia with ringed sideroblasts (RARS)

57
Q

idiopathic SA often ends in…

A

leukemia

58
Q

micro/hypo anemia with ↓ retics

A

sideroblastic anemia

RS lyse before release into PB

59
Q

increased RDW
pappenheimer bodies
high % sat transferrin

A

sideroblastic anemia

60
Q

iron-laden non-nucleated RBCs

A

siderocytes

61
Q

definitive direct test for assessing iron deposition and tissue damage in iron overload states

A

liver biopsy

Mercy CLS 6: Hematology (25 decks)

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