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MLSCI360 > IRON AND BILIRUBIN > Flashcards

IRON AND BILIRUBIN Flashcards

1
Q

Describe the methodology of the serum iron assay

A
  • transferrin releases ferric iron in acidic conditions
  • ferric iron is reduced to ferrous iron
  • ferrous iron complexes with a chromogen = increased absorbance is measured
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2
Q

Ref: Iron

A

8-35 μmol/L

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3
Q

Ref: TIBC

A

40-75 μmol/L

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4
Q

Ref: Saturation Index

A

Female: 0.12 - 0.60

Male: 0.10 - 0.55

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5
Q

Ref: Ferritin

A

Female: 20 - 300 μg/L

Male: 30 - 500 μg/L

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6
Q

Ref: Transferrin

A

1.8 - 4.5 g/L

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7
Q

Ref: Total bilirubin

A

<20 μmol/L

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8
Q

Ref: Conjugated (direct) bilirubin

A

<7 μmol/L

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9
Q

Less than 0.1% of the body’s iron is present in plasma as __.

A

Less than 0.1% of the body’s iron is present in plasma as transferrin.

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10
Q

What is apotransferrin ?

A
  • plasma protein
  • transports ferric iron (Fe3+)
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11
Q

Plasma iron levels are highest in the __ and progressively __ over the day.

A

Plasma iron levels are highest in the MORNING and progressively DECLINE over the day.

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12
Q

What conditions are associated with increased serum iron ?

A
  • hemochromatosis
  • iron medication intake
  • hormonal contraceptives
  • aplastic anemia
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13
Q

What conditions are associated with decreased serum iron ?

A
  • iron deficiency anemia
  • hemorrhage
  • menstruation
  • medication
  • anemia of chronic disease
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14
Q

How is TIBC measured ?

A
  1. Serum iron bound to transferrin is measured
  2. Excess ferric iron is added to saturate binding sites of transferrin; unbound excess iron is removed
  3. Serum iron assay is performed again and compared to the first measurement
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15
Q

How is excess iron removed during TIBC measurement ?

A
  • Using either a silica or anion exchange column

OR

  • Addition of magnesium carbonate
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16
Q

What causes increased TIBC ?

A
  • iron deficiency anemia
  • pregnancy
  • oral contraceptives
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17
Q

What causes decreased TIBC ?

A
  • chronic inflammatory disease
  • malignancy
  • hemochromatosis
18
Q

Transferrin Saturation Calculation

A

Tsat% = [serum iron] / TIBC x 100%

19
Q

What is ferritin ?

A
  • the major storage form of iron
  • acute phase reactant
  • found in bone marrow, liver, spleen
20
Q

What causes increased ferritin ?

A
  • malignancies
  • chronic infections
  • hemochromatosis
  • chronic inflammatory diseases (ie. SLE)
  • hepatitis
21
Q

The iron/ apotransferrin complex is also called __.

A

The iron/ apotransferrin complex is also called TRANSFERRIN.

22
Q

Transferrin migrates to the __ region in SPE

A

Transferrin migrates to the β region in SPE

23
Q

List 2 methods used to measure transferrin

A
  • Immunoturbidimetry
  • immunonephelometry
24
Q

What causes increased transferrin ?

A
  • pregnancy
  • administration of estrogen
  • iron deficiency
25
Q

What causes decreased transferrin ?

A
  • inflammation or malignancy (negative APR)
  • decreased synthesis; chronic liver disease, malnutrition
  • protein loss; nephrotic syndrome
26
Q

What is FIT ?

A

Fecal Immunochemical Testing:
- detects hemoglobin in feces
- screening test for colorectal cancer
- 50 years+ should be tested every 2 years

27
Q

What is bilirubin ?

A
  • degradation product of heme
  • transported in blood bound to albumin
  • conjugated in liver and excreted into intestine with bile
  • in the intestine, it is converted into urobilinogen
28
Q

Describe the Diazo method for total Bilirubin + Interferences

A
  • caffeine-benzoate-acetate is used to free unconjugated bilirubin from albumin (an accelerant)

Interferences:
- hemolysis, light exposure = false decrease
- lipemia = false increase

29
Q

Describe the Direct Spectrophotometry method for Unconjugated Bilirubin + Interferences

A
  • exclusively for neonates

Interferences:
- carotenoids absorb at 454nm; newborns do not have carotene

30
Q

What is associated with neonatal jaundice ?

A
  • immature liver cannot conjugate bilirubin and synthesize proteins
  • intestinal flora is not developed = conjugated bilirubin cannot be reduced to urobilinogen for excretion
  • hemoglobin F/ hemolytic disease of newborn = increased hemoglobin catabolism
  • kernicterus = unconjugated bilirubin crosses blood-brain barrier
31
Q

How can neonatal jaundice be treated ?

A

UV light therapy

32
Q

Critical total bilirubin for children <30 days

A

> 300 µmol/L

33
Q

Critical total bilirubin for children <30 days

A

> 300 µmol/L

34
Q

Describe pre-hepatic bilirubin

A

INCREASED TOTAL bilirubin, INCREASED UNCONJUGATED bilirubin, normal conjugated bilirubin, negative urine bilirubin

  • hemolytic anemia produces more bilirubin than the liver can process
35
Q

Describe hepatic bilirubin

A

INCREASED TOTAL bilirubin, variable unconjugated bilirubin, variable conjugated bilirubin, variable urine bilirubin

  • hepatocyte damage
  • inherited disorders; inability to take up unconjugated bilirubin OR excrete conjugated bilirubina
36
Q

Desribe post-hepatic bilirubin

A

INCREASED TOTAL bilirubin, normal unconjugated bilirubin, INCREASED CONJUGATED bilirubin, POSITIVE urine bilirubin

  • CHOLESTASIS/ gallstones
  • spasms or neoplasms prevent bilirubin from reaching intestine
37
Q

Describe post-hepatic bilirubin

A

INCREASED TOTAL bilirubin, normal unconjugated bilirubin, INCREASED CONJUGATED bilirubin, POSITIVE urine bilirubin

  • CHOLESTASIS/ gallstones
  • spasms or neoplasms prevent bilirubin from reaching intestine
38
Q

Differentiate Crigler-Naijar Syndrome Type I vs Type II

A

Inherited disorders of bilirubin metabolism

Type I:
- absence of UDP-glucoronyltransferase = HIGH UNCONJUGATED bilirubin
- kernicterus = severe brain damage/ death
- autosomal recessive

Type II:
- partial deficiency of UDP-glucoronyltransferase
- normal life expectancy w/ phenobarbital administration
- autosomal dominant

39
Q

What is Dubin-Johnson/ Rotor Syndrome ?

A
  • inherited disorder of bilirubin metabolism
  • autosomal recessive
  • HIGH CONJUGATED bilirubin with only slight increase in unconjugated bilirubin
  • problem in excretion of conjugated bilirubin from hepatic microsome into canaliculi
40
Q

What is Gilbert Syndrome ?

A
  • inherited disorder of bilirubin metabolism
  • autosomal recessive
  • MILD increase in unconjugated bilirubin; no treatment needed
41
Q

What is Lucey-Driscoll Syndrome ?

A
  • inherited disorder of bilirubin metabolism
  • inhibiton of bilirubin conjugation = HIGH UNCONJUGATED bilirubin
  • occurs early neonatal period through 2-3 weeks post-delivery
42
Q

TIBC Formula

A

TIBC = Serum iron + UIBC

MLSCI360 (22 decks)

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