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Clinical Chemistry 2 > 4. Iron Studies > Flashcards

4. Iron Studies Flashcards

1
Q

Excess in later intermediates (URO, COPRO, PROTO) of porphyrin/heme synthesis pathway causes ________ symptoms

A

cutaneous

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2
Q

How to distinguish true from secondary porphyrias?

A

Measure urinary ALA and PBG. In secondary:

  • ALA increased
  • PBG normal
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3
Q

Porphyrin compound excreted in urine

A

URO

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4
Q

Present in early childhood w/ extreme photosensitivity

A

Congenital erythropoietic porphyria (CEP)

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5
Q

Presence of an isomer of COPRO (isocoproporphyrin) is distinctive of PCT in this test

A

Fecal porphyrins

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6
Q

Increased in all porphyrias except in Acute Intermittent Porphyria

A

Fecal porphyria

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7
Q

Porphyrin compound excreted in feces

A

PROTO

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8
Q

What happens to oxygen when there is a RIGHT shift?

A

Hgb more likely to RELEASE O2 to tissues (decreased oxygen affinity of Hgb)

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9
Q

Enzyme deficiency in PP

A

Ferrochelatase

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10
Q

Low iron in anemia of chronic illness is due to?

A

Macrophages holding back iron availability for RBC production

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11
Q

Enzyme deficiency in HCP

A

Coprophyrinogen oxidase

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12
Q

Enzyme deficiency in CEP

A

Uroporphyrinogen III synthase

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13
Q

Porphyrin compound excreted in EITHER urine or feces

A

COPRO

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14
Q

Irreversrible chemical alteration of hemoglboin

A

Sulfhemoglobin

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15
Q

Early indicator of hemochromatoesis

A

Increased ferritin

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16
Q

Most common type of porphyria; remains dormant until some form of liver dysfunction

A

Porphyria cutanea tarda (PCT)

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17
Q

Most hemoglobin is degraded via this pathway

A

Extravascular hemolysis

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18
Q

What causes the formation of methemoglobin?

A

Oxidation of ferrOus to ferrIC iron in hgb = cannot reversibly bind oxygen

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19
Q

Colour of carboxyhemoglobin?

A

Bright cherry red

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20
Q

Free erythrocyte protoporphyrin (FEP) reflects concentrations of __________

A

zinc protoporphyrin (ZPP)

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21
Q

2 neurocutaneous porphyrias?

A
  • Hereditary coproporphyria (HCP)

- Variegate porphyria (VP)

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22
Q

2 most common SCREENING tests based on PBG (porphobilinogen) forming red-orange color when mixed with Ehrlichs

A
  • Watson-Schwarz

- Hoesch

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23
Q

%SO2 formula

A

%SO2 = O2hgb/(O2hgb + HHgb) * 100%

24
Q

Enzyme deficiency in VP

A

Protoporhyrinogen oxidase

25
How to interpret Part 2 of Schillings test?
>7% 58Co-B12 in urine = pernicious anemia <7% = bacterial or parasitic consumption of B12
26
This test is increased in protoporphyria (PROTO) and congenital erythropoietic porphyria (URO + COPRO)
RBC porphyrins
27
Those w/ this porphyria will have RBCs that fluoresce under UV due to large amounts of URO and COPRO
CEP
28
2 main sites of porphyrin synthesis
Bone marrow | Liver
29
Unbound hemoglobin dimers are reabsorbed by the __________ and converted to __________
kidneys; hemosiderin
30
Excess in early precursors (ALA, PBG) of porphyrin/heme synthesis pathway causes ________ symptoms
neuropsychiatric
31
What stimulates ALA synthase production?
Low heme
32
Why would a hemolyzed sample be unsuitable for folate determination?
Release of RBC folate = falsely high
33
Porphyria where large amount of URO and distinctive 7-carboxyl porphyrin is present (in urine porphyrins test)
Porphyria Cutanea Tarda (PCT)
34
What indicates dietary B12 deficiency?
>7% radiolabelled B12 recovered from Schillings Test (Part 1)
35
How to interpret Part 1 of Schillings test?
>7% 57Co-B12 in urine = dietary deficiency <7% = malabsorption
36
FO2Hgb formula
FO2Hgb = O2Hgb/tHgb * 100%
37
How to distinguish variegate porphyria (VP) from hereditary coproporphyria (HCP)?
Fecal porphyrin test - VP should have both PROTO and COPRO elevated - HCP only COPRO elevated
38
Spectral analysis - term for the point at which 2 substances absorb a certain wavelength of light to the same extent
Isobestic point
39
Colour of methemoglobin?
Brown
40
Lead poisoning classically exhibits increased what 3 things?
- Urine COPRO - Urine ALA - RBC ZPP
41
Enzyme deficiency in AIP
PBG deaminase
42
Enzyme deficiency in PCT
Uroporphyrinogen decarboxylase
43
2 causes of increased free erythrocyte protoporphyrin (FEP)
- iron deficiency | - lead poisoning
44
These values are increased in all 4 neurological porphyrias
Urine ALA
45
Treatment for extreme case of sulfhemoglobin?
Blood transfusions
46
Urine porphyrins test would be elevated in all but this porphyria
Protoporphyria (PP)
47
CO2 bound covalengtly to hgb is called..?
Carbaminohemoglobin
48
What occurs to hemoglobin in intravascular hemolysis
Dissociated alpha/beta dimers bind to haptoglobin Haptoglobin complex removed from circulation by liver
49
Specimen required for co-oximeter
Whole blood
50
2 heme-forming tissues
Liver | RBCs
51
Excess in early and late intermediates of porphyrin/heme synthesis pathway causes ________ symptoms
neurocutaneous
52
How does pulse oximeter work
O2Hgb absorbs more infrared light and allows more red light to pass DeoxyHgb is opposite Ratio is reported
53
Difference between HYPOXIA and HYPOXEMIA
Hypoxia = low O2 in tissues Hypoxemia = low O2 in blood
54
Accumulation of these 2 molecules result in photosensitivity and cutaneous lesions in VP
- Protoporphyrinogen IX | - Coproporphyrinogen III
55
Early indicator of IDA
Decreased ferritin
56
Increased fecal and RBC PROTO is a key finding for this porphyria
Protoporphyria (PP)

Clinical Chemistry 2 (15 decks)

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