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Clinical Chemistry 2 > 4. Iron Studies > Flashcards

4. Iron Studies Flashcards

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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
Q

How to interpret Part 2 of Schillings test?

A

> 7% 58Co-B12 in urine = pernicious anemia

<7% = bacterial or parasitic consumption of B12

26
Q

This test is increased in protoporphyria (PROTO) and congenital erythropoietic porphyria (URO + COPRO)

A

RBC porphyrins

27
Q

Those w/ this porphyria will have RBCs that fluoresce under UV due to large amounts of URO and COPRO

A

CEP

28
Q

2 main sites of porphyrin synthesis

A

Bone marrow

Liver

29
Q

Unbound hemoglobin dimers are reabsorbed by the __________ and converted to __________

A

kidneys; hemosiderin

30
Q

Excess in early precursors (ALA, PBG) of porphyrin/heme synthesis pathway causes ________ symptoms

A

neuropsychiatric

31
Q

What stimulates ALA synthase production?

A

Low heme

32
Q

Why would a hemolyzed sample be unsuitable for folate determination?

A

Release of RBC folate = falsely high

33
Q

Porphyria where large amount of URO and distinctive 7-carboxyl porphyrin is present (in urine porphyrins test)

A

Porphyria Cutanea Tarda (PCT)

34
Q

What indicates dietary B12 deficiency?

A

> 7% radiolabelled B12 recovered from Schillings Test (Part 1)

35
Q

How to interpret Part 1 of Schillings test?

A

> 7% 57Co-B12 in urine = dietary deficiency

<7% = malabsorption

36
Q

FO2Hgb formula

A

FO2Hgb = O2Hgb/tHgb * 100%

37
Q

How to distinguish variegate porphyria (VP) from hereditary coproporphyria (HCP)?

A

Fecal porphyrin test

  • VP should have both PROTO and COPRO elevated
  • HCP only COPRO elevated
38
Q

Spectral analysis - term for the point at which 2 substances absorb a certain wavelength of light to the same extent

A

Isobestic point

39
Q

Colour of methemoglobin?

A

Brown

40
Q

Lead poisoning classically exhibits increased what 3 things?

A
  • Urine COPRO
  • Urine ALA
  • RBC ZPP
41
Q

Enzyme deficiency in AIP

A

PBG deaminase

42
Q

Enzyme deficiency in PCT

A

Uroporphyrinogen decarboxylase

43
Q

2 causes of increased free erythrocyte protoporphyrin (FEP)

A
  • iron deficiency

- lead poisoning

44
Q

These values are increased in all 4 neurological porphyrias

A

Urine ALA

45
Q

Treatment for extreme case of sulfhemoglobin?

A

Blood transfusions

46
Q

Urine porphyrins test would be elevated in all but this porphyria

A

Protoporphyria (PP)

47
Q

CO2 bound covalengtly to hgb is called..?

A

Carbaminohemoglobin

48
Q

What occurs to hemoglobin in intravascular hemolysis

A

Dissociated alpha/beta dimers bind to haptoglobin

Haptoglobin complex removed from circulation by liver

49
Q

Specimen required for co-oximeter

A

Whole blood

50
Q

2 heme-forming tissues

A

Liver

RBCs

51
Q

Excess in early and late intermediates of porphyrin/heme synthesis pathway causes ________ symptoms

A

neurocutaneous

52
Q

How does pulse oximeter work

A

O2Hgb absorbs more infrared light and allows more red light to pass

DeoxyHgb is opposite

Ratio is reported

53
Q

Difference between HYPOXIA and HYPOXEMIA

A

Hypoxia = low O2 in tissues

Hypoxemia = low O2 in blood

54
Q

Accumulation of these 2 molecules result in photosensitivity and cutaneous lesions in VP

A
  • Protoporphyrinogen IX

- Coproporphyrinogen III

55
Q

Early indicator of IDA

A

Decreased ferritin

56
Q

Increased fecal and RBC PROTO is a key finding for this porphyria

A

Protoporphyria (PP)

Clinical Chemistry 2 (15 decks)

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