Heme synthesis Flashcards

1
Q

What is needed for ALA synthase?

A

Vit B6

Deficiency→anemia

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2
Q

Defective ALA dehydratase symptoms

A

Acute attacks of abdominal pain and neuropathy

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3
Q

Defective PBG deaminase (in liver)

A

Acute intermittent porphyria: abdominal pain, neurologic dysfunction

Type: hepatic

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4
Q

Defective Protoporphyrinogen IX oxidase

A

Variegate porphyria: photosensitivity, developmental delay in children

Type: Hepatic

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5
Q

Defective Ferrochelatase

A

Erythropoietic protoporphyria: Photosensitivity w/ skin lesions after brief sun exposure, gallstones, mild liver dysfunction

Type: erythropoietic

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6
Q

Unconjugated (“indirect”) bilirubin

A

Hemoglobin is broken down, heme is then turned into unconjugated bilirubin in the spleen. This unconjugated bilirubin is insoluble in water. It is then bound to albumin and sent to the liver.

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7
Q

Conjugated (“direct”) bilirubin

A

In the liver, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase, making it soluble in water

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8
Q

Jaundice

A

Too much bilirubin or not getting rid of it correctly

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9
Q

Pre-hepatic jaundice (hemolytic)

A

↑ unconjugated bilirubin

  • hemolytic anemias
  • internal hemorrage
  • G6P dehydrogenase deficiency
  • Neonatal jaundice due to problem w/ maternal/fetal blood groups (baby’s conjugation enzymes aren’t up and running yet when it’s trying to get rid of fetal Hb)
Symptoms: 
↑ unconjugated BR
-normal conjugated BR
-normal ALT & AST
-Urobilinogen present in urine
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10
Q

Intra-hepatic jaundice

A

-Impaired hepatic uptake, conjugation, or secretion ofconjugated BR

Liver dysfunction

  • liver cirrhosis
  • viral hepatitis
  • Criggler-Najjar syndrom
  • Gilbert syndrom

Symptoms:

  • ↑ALT/AST
  • urobilinogen present in urine
  • conjugated BR detected in urine
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11
Q

Post-hepatic

A
  • Problems w/ release
  • Cholestasis (decreased bile flow)
Symptoms:
↑ blood conjugated BR w/ much smaller increases in unconjugated form
-Normal ALT/AST
↑ ALP
↑ bile salts (b/c preventing release)
-Urine is dark
-Conjugated BR in urine
-No urobilinogen in urine
-Pale stool
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12
Q

Neonatal jaundice

A
  • Deficiency of UDP-GT enzyme
  • Immature hepatic pathways-unable to conjugate and excrete bilirubin

Treatment: UV light–>breaks down bilirubin

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13
Q

Criggler-Najjar syndrome

A

Cause: UDP-GT deficiency

Type 1: complete loss of gene

Symptoms:
-severe hyperbilirubinemia (accumulates in brain of affected newborns–>causes kernicturus)

Treatment:

  • Phototherapy
  • Blood transfusions
  • Heme oxygenase inhibitors
  • Oral Calcium phosphate
  • Liver translation

Type 2: benign form (mutation in gene)

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14
Q

Gilbert Syndrome

A

Reduced activity of UDP-GT activity. Not as serious as Crigler-Najjar

Serum BR

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15
Q

Hepatitis

A

Liver inflammation

  • Leads to liver dysfunction
  • Causes ↑ levels conjugated/unconjugated BR in blood
  • Accumulates in skin & sclera of eyes→yellow discoloration, urine is tea colored
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